Types of Chemical Reactions Online Test 10th Science Lesson 10 Questions in English

Types of Chemical Reactions Online Test 10th Science Lesson 10 Questions in English

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Question 1
Which of the following are involved in chemical reaction?
  1. Breaking of old chemical bonds
  2. Formation of a substance which has a property other than that of reactants
  3. Formation of new chemical bonds
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 1 Explanation: 
A chemical reaction involves breaking of old chemical bonds and formation of new chemical bonds. This change may happen spontaneously or it may be facilitated by external forces or energy. A chemical reaction does not involve in formation of a substance which has a property other than that of reactants.
Question 2
Match the following:
  1. Human getting energy                 1. Combustion of a fuel
  2. Plants growing                               2. Digestion of food
  3. Moving car                                     3. Oxidation of iron
  4. Rusting                                            4. Absorbing nutrients from soil
A
3, 1, 2, 4
B
2, 4, 1, 3
C
2, 4, 3, 1
D
2, 1, 3, 4
Question 2 Explanation: 
Human gets energy from the digestion of the food you eat. Plants grow by absorbing nutrients from the Earth and get their food by photosynthesis. The combustion of a fuel makes the car to move. Oxidation of iron causes rusting.
Question 3
Which of the following are the resultants of burning of petrol?
  1. Water
  2. Carbon Monoxide
  3. Carbon Di-oxide
A
1, 3
B
1, 2
C
2, 3
D
All the above
Question 3 Explanation: 
In chemical reaction process chemical changes i.e. the materials, which undergo changes are converted into some other new materials. For example, by burning petrol, the hydrocarbons present in it are converted into carbon dioxide and water.
Question 4
Which of the following happens during a chemical reaction?
A
In a chemical reaction, the atoms of the reacting molecules or elements are rearranged to form new molecules.
B
Old chemical bonds between atoms are broken and new chemical bonds are formed
C
Bond breaking absorbs energy whereas bond formation releases energy
D
All the above
Question 4 Explanation: 
In a chemical reaction following changes happen: In a chemical reaction, the atoms of the reacting molecules or elements are rearranged to form new molecules. Old chemical bonds between atoms are broken and new chemical bonds are formed. Bond breaking absorbs energy whereas bond formation releases energy
Question 5
In a chemical reaction compounds which undergo reactions are called as_______
A
Products
B
Reactants
C
Catalyst
D
None
Question 5 Explanation: 
In the chemical equation, the chemicals of the reaction are represented by their chemical formulas. Compounds or elements, which undergo reactions (reactants) are shown to the left of an arrow and the compounds formed (products) are shown to the right of the arrow. The arrow indicates the direction of the reaction.
Question 6
A + B >>> C + D
  • A                1. Oxygen
  • B                2. Methane
  • C                3. Water
  • D                4. CO2
Match the following correctly:
A
3, 1, 2, 4
B
2, 1, 4, 3
C
4, 1, 2, 3
D
4, 3, 2, 1
Question 6 Explanation: 
When methane reacts with oxygen, it forms carbon dioxide and water. How can you represent this reaction? It can be written as a word equation as shown below: Methane + Oxygen → Carbon dioxide + Water CH4 + O2 → CO2 + H2 O
Question 7
  • Assertion(A): This is an incomplete chemical equation
  • Reason(R): The law of conservation of matter states that matter cannot be created or destroyed.
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is Correct and (R) is wrong
Question 7 Explanation: 
CH4 + O2 → CO2 + H2 O This is also an incomplete chemical equation. Because, the law of conservation of matter states that matter cannot be created or destroyed. You cannot create new atoms by a chemical reaction. In contrast, they are rearranged in different ways by a chemical reaction to form a new compound. So, in a chemical equation, the number of atoms of the reactants and that of the products must be equal.
Question 8
Which of the following is the correct balanced chemical reaction?
A
CH4 + 2O2 → CO2 + 2H2 O
B
CH4 + 2O2 → CO2 + H2 O
C
CH4 + O2 → CO2 + 2H2 O
D
2CH4 + 2O2 → CO2 + 2H2 O
Question 8 Explanation: 
A balanced chemical equation is the simplified representation of a chemical reaction which describes the chemical composition, physical state of the reactants and the products, and the reaction conditions.
Question 9
The physical state of the substances in a chemical reaction are denoted in short form within a bracket, as the_____ of the formula
A
Super subscript
B
Subscript
C
Mega subscript
D
None
Question 9 Explanation: 
The phases or the physical state of the substances in a chemical reaction are denoted in short form within a bracket, as the subscript of the formula, of the respective substances.
Question 10
Match the following substances with their state when potassium reacts with water?
  1. Potassium                                    1. Liquid
  2. Water                                            2. Gas
  3. Hydrogen                                     3. Aqueous solution
  4. Potassium hydroxide                4. Solid
A
2, 1, 4, 3
B
4, 1, 2, 3
C
1, 3, 2, 4
D
4, 2, 1, 3
Question 10 Explanation: 
When solid potassium reacts with liquid water, it produces hydrogen gas and potassium hydroxide solution. All the information of the reaction is given in the chemical equation as shown below: 2K(s) + 2H2 O(I) → 2KOH (aq) + H2(g)
Question 11
___________ is a reaction in which two or more reactants combine to form a compound
A
Combination reaction
B
De-combination reaction
C
Redox reaction
D
None
Question 11 Explanation: 
A combination reaction is a reaction in which two or more reactants combine to form a compound. It is otherwise called 'synthesis reaction' or 'composition reaction'.
Question 12
Hydrogen gas combines with chlorine gas to form______
A
Hydrogen chloride gas
B
HCl acid
C
Aqueous solution of HCl
D
None
Question 12 Explanation: 
Hydrogen gas combines with chlorine gas to form hydrogen chloride gas. H2(g) + Cl2(g) → 2HCl(g)
Question 13
Depending on chemical nature of the reactant, combination reaction is classified into___ types
A
3
B
2
C
5
D
4
Question 13 Explanation: 
Depending on the chemical nature of the reactants, there are three classes of combination reactions: Element + Element → Compound Compound + Element → Compound Compound + Compound → Compound
Question 14
When Solid sulphur reacts with oxygen forms_____
A
Sulphur dioxide
B
Sulphur oxide
C
Sulphuric oxide
D
Hydrogen Sulphide
Question 14 Explanation: 
When solid sulphur reacts with oxygen, it produces sulphur dioxide. Here both the reactants are non-metals. S(s) + O2(g) → SO2(g)
Question 15
What is the colour of Sodium and Chlorine gas?
A
White, green
B
White, Pale yellow green
C
Pale yellow, white
D
White, White
Question 15 Explanation: 
Sodium, a silvery-white metal, combines with chlorine, a pale-yellow green gas, to form sodium chloride, an edible compound. Here one of the reactants is a metal (sodium) and the other (chlorine) is a nonmetal. 2Na(s) + Cl2(g) → 2NaCl(s)
Question 16
Which of the following is a Compound + Element reaction?
A
H2 + Cl2 → 2HCl
B
PCl3 + Cl2 → PCl5
C
SiO2 + CaO → CaSiO3
D
None
Question 16 Explanation: 
A compound reacts with an element to form a new compound. For instance, phosphorous trichloride reacts with chlorine gas and forms phosphorous pentachloride. PCl3(I) + Cl2(g) → PCl5(s)
Question 17
Most of the combination reactions are_____ in nature
A
Exothermic
B
Endothermic
C
Redox
D
None
Question 17 Explanation: 
In the following reaction, silicon dioxide reacts with calcium oxide to form calcium silicate. SiO2(s) + CaO(s) → CaSiO3(s) Most of the combination reactions are exothermic in nature. Because, they involve the formation of new bonds, which releases a huge amount of energy in the form of heat.
Question 18
Which of the following statement about decomposition reaction is/are incorrect?
  1. In a decomposition reaction, a single compound splits into two or more simpler substances under suitable conditions
  2. It is the opposite of the combination reaction
 
A
1 alone
B
2 alone
C
1, 2
D
None
Question 18 Explanation: 
In a decomposition reaction, a single compound splits into two or more simpler substances under suitable conditions. It is the opposite of the combination reaction
Question 19
Depending on the nature of energy used in decomposition reaction it is classified into____ types
A
2
B
5
C
3
D
4
Question 19 Explanation: 
Breaking of bonds is the major phenomenon in a decomposition reaction and hence it requires energy to break the bonds, depending on the nature of the energy used in the decomposition reaction. There are three main classes of decomposition reactions. They are Thermal Decomposition Reactions Electrolytic Decomposition Reactions Photo Decomposition Reactions
Question 20
Which of the following is used in white washing walls?
A
Calcium oxide
B
Calcium carbonate
C
Slaked lime
D
None
Question 20 Explanation: 
A solution of slaked lime is used for white washing walls. Calcium hydroxide reacts slowly with the carbon dioxide in air to form a thin layer of calcium carbonate on the walls.
Question 21
What is the chemical formula of marble?
A
CaCO3
B
CaO
C
Ca (OH)2
D
NaCl
Question 21 Explanation: 
Calcium carbonate is formed aft er two to three days of white washing and gives a shiny finish to the walls. It is interesting to note that the chemical formula for marble is also CaCO3.
Question 22
What is the product of the reaction? Ca (OH)2(aq) + CO2(g) →____ +______
A
CaO, H2O
B
CaCO3, H2O
C
Ca (OH)2, H2O
D
CaCO3, O2
Question 23
What happens when mercury (II) oxide is heated?
A
Mercury metal and oxygen gas is formed
B
Mercury Dioxide is formed
C
Mercury Trioxide is formed
D
None
Question 23 Explanation: 
In Thermal Decomposition Reactions, the reactant is decomposed by applying heat. For example, on heating mercury (II) oxide is decomposed into mercury metal and oxygen gas. As the molecule is dissociated by the absorption of heat, it is otherwise called ‘Thermolysis’. It is a class of compound to element/element decomposition. i.e. a compound (Hg O) is decomposed into two elements (Hg and Oxygen).
Question 24
What happens when calcium carbonate is heated?
A
Calcium oxide and carbon dioxide formed
B
Calcium Hydroxide and carbon dioxide
C
Calcium and water
D
Calcium Carboxylic acid formed
Question 24 Explanation: 
When calcium carbonate is heated, it breaks down in to calcium oxide and carbon dioxide. It is a type of compound to compound/compound decomposition.
Question 25
Thermal decomposition is_______ reaction
A
Exothermic
B
Endothermic
C
Redox
D
Reduction
Question 25 Explanation: 
In thermal decomposition reaction, heat is supplied to break the bonds. Such reactions, in which heat is absorbed, are called ‘Endothermic reactions’
Question 26
  • Assertion(A): Decomposition of sodium chloride occurs on passing electric current through its  aqueous solution
  • Reason(R): In some of the decomposition reactions, electrical energy is used to bring about the Reaction
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is Correct and (R) is wrong
Question 26 Explanation: 
In some of the decomposition reactions, electrical energy is used to bring about the reaction. For example, decomposition of sodium chloride occurs on passing electric current through its aqueous solution. Sodium chloride decomposes in to metallic sodium and chlorine gas. Th is process is termed as ‘Electrolysis’.
Question 27
The decomposition reaction is called as_____
A
Thermolysis
B
Photolysis
C
Electrolysis
D
Photosynthesis
Question 27 Explanation: 
Light is another form of energy, which facilitates some of the decomposition reactions. As the decomposition is caused by the light, this kind of reaction is also called ‘Photolysis’.
Question 28
What will be the colour of silver bromide in absence of sunlight?
A
Grey colour
B
Light yellow
C
Light green
D
Silver brown
Question 28 Explanation: 
Th e yellow coloured silver bromide turns into grey coloured silver metal when placed in sunlight. It is also a compound to element/element decomposition.
Question 29
Which of the following is single displacement reaction?
  1.  Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2 O(I)
  2. 2AgBr(s) → 2Ag(s) + Br2(g)
  3. Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
  4. Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)
A
1, 2
B
1, 3
C
2, 3
D
2, 4
Question 29 Explanation: 
Single Displacement Reactions is a reaction between an element and a compound. When they react, one of the elements of the compound-reactant is replaced by the element-reactant to form a new compound and an element. Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)
Question 30
Arrange the most reactive elements in order:
  1. Potassium
  2. Zinc
  3. Hydrogen
  4. Platinum
A
1, 3, 4, 2
B
2, 3, 4, 1
C
4, 3, 2, 1
D
1, 2, 3, 4
Question 31
2NaCl(aq) + F2(g) →
A
NaF, Cl2
B
2NaF, Cl2
C
2NaF, Cl3
D
NaF2, 2Cl
Question 31 Explanation: 
2NaCl(aq) + F2(g) → 2NaF(aq) + Cl2(g) 2NaF(aq) + Cl2(g) → 2NaCl(aq) + F2(g) Th e first reaction involves the displacement of chlorine from NaCl, by fluorine. In the second reaction, chlorine displaces fluorine from NaF. Out of these two, the second reaction will not occur. Because, fluorine is more active than chlorine and occupies the upper position in the periodic table.
Question 32
Which of the following statement is correct?
  1. When two compounds react, if their ions are interchanged, then the reaction is called double displacement reaction.
  2. The ion of one compound is replaced by the ion of another compound
  3. This reaction is also called ‘Metathesis Reaction’
 
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 32 Explanation: 
When two compounds react, if their ions are interchanged, then the reaction is called double displacement reaction. Th e ion of one compound is replaced by the ion of another compound. Ions of identical charges are only interchanged, i.e., a cation can be replaced by other cations. Th is reaction is also called ‘Metathesis Reaction’
Question 33
For a double displacement reaction to take place_____
A
Both products must be precipitate alone
B
One of the products, must be water alone
C
One of the products must be a precipitate or water
D
None
Question 33 Explanation: 
For a double displacement reaction to take place, one of the products must be a precipitate or water. By this way, there are major classes of double displacement reactions. They are: Precipitation Reactions Neutralization Reactions
Question 34
Which of the following statement about decomposition reaction is correct?
  1. A single reactant is decomposed to form one or more products
  2. Energy is released
  3. Single compound is the reactant
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 35
What is the colour of lead (II) iodide?
A
Blue
B
Yellow
C
Red
D
Green
Question 35 Explanation: 
When the clear aqueous solutions of potassium iodide and lead (II) nitrate are mixed, a double displacement reaction takes place between them. Pb(NO3 )2(aq) + 2KI(aq) → PbI2(s)↓ + 2KNO3(aq) Potassium and lead displace or replace one other and form a yellow precipitate of lead (II) iodide
Question 36
The product of Neutralization Reaction is always______
A
Acid
B
Base
C
Salt
D
None
Question 36 Explanation: 
In your lower classes, you have learned the reaction between an acid and a base. It is another type of displacement reaction in which the acid reacts with the base to form a salt and water. It is called 'neutralization reaction' as both acid and base neutralize each other.
Question 37
NaOH(aq) + HCl(aq) →
A
NaH2, OH
B
NaCl, H2O
C
HCl, Na (OH)2
D
HOCl, Na
Question 37 Explanation: 
Reaction of sodium hydroxide with hydrochloric acid is a typical neutralization reaction. Here, sodium replaces hydrogen from hydrochloric acid forming sodium chloride, a neutral soluble salt. NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
Question 38
Which of the following statement is correct?
  1. A combustion reaction is one in which the reactant rapidly combines with oxygen to form one or more oxides and energy
  2. Combustion reactions are majorly used as heat energy sources in many of our day to day activities.
A
1 alone
B
2 alone
C
1, 2
D
None
Question 38 Explanation: 
A combustion reaction is one in which the reactant rapidly combines with oxygen to form one or more oxides and energy (heat). So, in combustion reactions one of the reactants must be oxygen. Combustion reactions are majorly used as heat energy sources in many of our day to day activities. For instance, we use LPG gas for domestic cooking purposes.
Question 39
Which of the following are the mixture of LPG?
  1. Propane
  2. Butane
  3. Propylene
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 39 Explanation: 
LPG is a mixture of hydrocarbon gases like propane, butane, propylene, etc. All these hydrocarbons burn with oxygen to form carbon dioxide and water. C3 H8(g) + 5O2(g) → 3CO2(g) + 4H2 O(g) + Heat
Question 40
Which of the following statement is correct?
  1. All combustion reactions are oxidation reaction
  2. All oxidation reactions are not combustion
  3. Combustion reaction is an exothermic reaction
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 40 Explanation: 
Since heat is evolved, it is an exothermic reaction. As oxygen is added, it is also an oxidation. So, combustion may be called as an exothermic oxidation.
Question 41
Which of the following is a combustion?
  1. Digestion of Food
  2. Rusting of iron
  3. Evaporation of water
A
1, 2
B
1, 3
C
2, 3
D
None
Question 41 Explanation: 
Digestion of Food Rusting of iron None of the reaction is combustion reaction, because digestion food is endothermic reaction and rusting of iron does not produce energy.
Question 42
  • Assertion(A): Liquid water freezes into ice, it is a permanent change
  • Reason(R): Physical changes can be reversed easily.
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is wrong and (R) is correct
Question 42 Explanation: 
You know that innumerable changes occur every day around us. For example, liquid water freezes into ice, but then ice melts into liquid water. In other words, freezing is reversed. So, it is not a permanent change. Moreover, it is a physical change. Physical changes can be reversed easily.
Question 43
Which of the following statement is correct?
  1. The carbon compounds present in the wood are burnt into carbon dioxide gas and water.
  2. Some chemical reactions can be reversed
  3. On recharging the mobile, these chemical reactions are reversed.
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 43 Explanation: 
Let us consider the burning of a wood. The carbon compounds present in the wood are burnt into carbon dioxide gas and water. Can we get back the wood immediately from carbon dioxide and water? We cannot. So, it is a permanent change. In most of the cases, we cannot. But, some chemical reactions can be reversed. Our mobile phone gets energy from its lithium-ion battery by chemical reactions. It is called discharging. On recharging the mobile, these chemical reactions are reversed. Thus, chemical reactions may be reversed under suitable conditions. Hence, they are grouped into two categories such as reversible and irreversible reactions.
Question 44
Which of the following statement about reversible reaction is correct?
  1. It is a reaction that can be reversed
  2. A reversible reaction is represented by a double arrow with their heads in the direction opposite to each other
  3. The products can be converted back to the reactants
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 44 Explanation: 
A reversible reaction is a reaction that can be reversed, i.e., the products can be converted back to the reactants. A reversible reaction is represented by a double arrow with their heads in the direction opposite to each other.
Question 45
Which of the following statement about forward reaction is the decomposition of PCl5 and the backward reaction is the combination of PCl3 and Cl2 is correct?
  1. Initially, the forward reaction proceeds faster than the backward reaction
  2. After sometimes, the speed of both the reactions become equal.
  3. PCl5 cannot be completely converted into the products as the reaction is reversed
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 45 Explanation: 
The forward reaction is the decomposition of PCl5 and the backward reaction is the combination of PCl3 and Cl2. Initially, the forward reaction proceeds faster than the backward reaction. Aft er sometimes, the speed of both the reactions become equal. So, PCl5 cannot be completely converted into the products as the reaction is reversed. It is a reversible reaction. Th e actual measurements of the given reaction show that the reaction is at equilibrium, but the amount of PCl5 is more than that of PCl3 and Cl2.
Question 46
If hydrogen peroxide is poured on a wound, it decomposes into______
A
Water and oxygen
B
Hydrogen and oxygen
C
Hydrochloric acid
D
Hydrogen and water
Question 46 Explanation: 
If hydrogen peroxide is poured on a wound, it decomposes into water and oxygen. Th e gaseous oxygen bubbles away as it is formed and thus prevent the formation of H2 O2. Thus, more amount of product can be obtained in a reversible reaction by the periodical removal of one of the products or the periodical addition of the reactants.
Question 47
Which of the following statement about irreversible reaction is correct?
  1. The reaction that cannot be reversed is called irreversible reaction.
  2. The combustion of coal into carbon dioxide and water is an example of irreversible reaction
  3. Backward reaction is not possible in this case
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 47 Explanation: 
The reaction that cannot be reversed is called irreversible reaction. Th e irreversible reactions are unidirectional, i.e., they take place only in the forward direction. Consider the combustion of coal into carbon dioxide and water. C(s) + O2(g) → CO2(g) + Heat In this reaction, solid coal burns with oxygen and gets converted into carbon dioxide gas and water. As the product is a gas, as soon as it is formed it escapes out of the reaction container. It is extremely hard to decompose a gas into a solid. Th us, the backward reaction is not possible in this case. So, it is an irreversible reaction.
Question 48
What does the negative sign indicate?
A
Increase in product
B
Decrease in reactant
C
Decrease in both product and reactant
D
None
Question 48 Explanation: 
Where, [A] – Concentration of A [B] – Concentration of B The negative sign indicates the decrease in the concentration of A with time. The positive sign indicates the increase in the concentration of B with time.
Question 49
Which of the following statement is correct?
  1. Faster the reaction, more will be the amount of the product in a specified time.
  2. Rate of reaction is also important for a food processor who hopes to slow down the reactions that cause food to spoil.
A
1 alone
B
2 alone
C
1, 2
D
None
Question 49 Explanation: 
Faster the reaction, more will be the amount of the product in a specified time. So, the rate of a reaction is important for a chemist for designing a process to get a good yield of a product. Rate of reaction is also important for a food processor who hopes to slow down the reactions that cause food to spoil.
Question 50
Iron gets rusted faster in__________
A
Acid
B
Bases
C
Water
D
None
Question 50 Explanation: 
The rate of a reaction can be changed. For example, iron gets rusted faster in an acid than in water. Some factors influence the rate of a reaction.
Question 51
Which of the following are the factors that affect rate of a reaction?
  1. Catalyst
  2. Pressure
  3. Nature of the reactants
  4. Temperature
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 51 Explanation: 
Important factors that affect rate of a reaction are Nature of the reactants Concentration of the reactants Temperature Catalyst Pressure Surface area of the reactants
Question 52
Which of the following reacts faster with sodium?
A
HCl
B
Acetic acid
C
Formic acid
D
None
Question 52 Explanation: 
The reaction of sodium with hydrochloric acid is faster than that with acetic acid. Hydrochloric acid is a stronger acid than acetic acid and thus more reactive. So, the nature of the reactant influence the reaction rate. 2Na(s) + 2HCl(aq) → 2NaCl(aq)+ H2 (g) (fast) 2Na(s) + 2CH3 COOH (aq) → 2CH3 COONa (aq)+ H2(g)(slow)
Question 53
  • Assertion(A): Changing the amount of the reactants also increases the reaction rate
  • Reason(R): More the concentration, more particles per volume exist in it and hence faster the reaction.
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is wrong and (R) is correct
Question 53 Explanation: 
Changing the amount of the reactants also increases the reaction rate. The amount of the substance present in a certain volume of the solution is called ‘concentration’. More the concentration, more particles per volume exist in it and hence faster the reaction. Granulated zinc reacts faster with 2M hydrochloric acid than 1M hydrochloric acid.
Question 54
  • Assertion(A): Calcium carbonate reacts slowly with hydrochloric acid at room temperature. When   heated reaction will be faster.
  • Reason(R): Most of the reactions go faster at higher temperature.
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is wrong and (R) is correct
Question 54 Explanation: 
Most of the reactions go faster at higher temperature. Because adding heat to the reactants provides energy to break more bonds and thus speed up the reaction. Calcium carbonate reacts slowly with hydrochloric acid at room temperature. When the reaction mixture is heated the reaction-rate increases.
Question 55
  • Assertion(A): Food kept at room temperature spoils faster than that kept in the refrigerator
  • Reason(R): Most of the reactions go faster at higher temperature.
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is wrong and (R) is correct
Question 55 Explanation: 
Food kept at room temperature spoils faster than that kept in the refrigerator. In the refrigerator, the temperature is lower than the room temperature and hence the reaction rate is less.
Question 56
If the reactants are gases, increasing their pressure______ the reaction rate.
A
Increases
B
Decreases
C
Initially increase then decreases
D
None
Question 57
On heating potassium chlorate, it decomposes into_______
A
KCl, O2
B
KOH, Cl2
C
KOCl2
D
KOH, H2
Question 57 Explanation: 
A catalyst is a substance which increases the reaction rate without being consumed in the reaction. In certain reactions, adding a substance as catalyst speeds up the reaction. For example, on heating potassium chlorate, it decomposes into potassium chloride and oxygen gas, but at a slower rate. If manganese dioxide is added, it increases the reaction rate.
Question 58
Which of the following statement is correct?
  1. When solid reactants are involved in a reaction, their powdered form reacts more readily
  2. Because, powdering of the reactants increases the surface area and more energy is available on collision of the reactant particles
A
1 alone
B
2 alone
C
1, 2
D
None
Question 58 Explanation: 
When solid reactants are involved in a reaction, their powdered form reacts more readily. For example, powdered calcium carbonate reacts more readily with hydrochloric acid than marble chips. Because, powdering of the reactants increases the surface area and more energy is available on collision of the reactant particles. Thus, the reaction rate is increased.
Question 59
Which of the following statement is correct?
  1. Although pure water is often considered as a non-conductor of electricity, precise measurements show that it conducts electricity to a little extent
  2. This conductivity of water has resulted from the self-ionisation of water
  3. The proton gets dissolved in water forming the hydronium ion
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 59 Explanation: 
Although pure water is often considered as a non-conductor of electricity, precise measurements show that it conducts electricity to a little extent. This conductivity of water has resulted from the self-ionisation of water. Self-ionisation or auto ionisation is a reaction in which two like molecules react to give ions. In the process of ionisation of water, a proton from one water molecule is transferred to another water molecule leaving behind an OH— ion. The proton gets dissolved in water forming the hydronium ion as shown in the following equation:
Question 60
  • Assertion(A): Initially the rate of the backward reaction is greater than the rate of the forward  Reaction
  • Reason(R): During the course of reaction, the concentration of the reactants decreases and the  concentration of the products increases.
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is wrong and (R) is correct
Question 60 Explanation: 
Initially the rate of the forward reaction is greater than the rate of the backward reaction. However, during the course of reaction, the concentration of the reactants decreases and the concentration of the products increases. Since the rate of a reaction is directly proportional to the concentration, the rate of the forward reaction decreases with time, whereas the rate of the backward reaction increases.
Question 61
Which of the following statement is correct?
  1. Not only chemical changes, physical changes also may attain equilibrium.
  2. Physical equilibrium is a state of a physical change at which the volume of all the phases remain unchanged.
A
1 alone
B
2 alone
C
1, 2
D
None
Question 61 Explanation: 
Not only chemical changes, physical changes also may attain equilibrium. When water kept in a closed vessel evaporates, it forms water vapour. No water vapour escapes out of the container as the process takes place in a closed vessel. So, it builds up the vapour pressure in the container. At one time, the water vapour condenses back into liquid water and when the rate of this condensation becomes equal to that of vapourisation, the process attains equilibrium. At this stage, the volume of the liquid and gaseous phases remain constant. Since it is a physical change, the equilibrium attained is called ‘Physical Equilibrium’. Physical equilibrium is a state of a physical change at which the volume of all the phases remain unchanged.
Question 62
Which of the following properties remain unchanged in a equilibrium reaction?
  1. Colour
  2. Viscosity
  3. Density
  4. Pressure
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 62 Explanation: 
Characteristics of equilibrium: In a chemical equilibrium, the rates of the forward and backward reactions are equal. The observable properties such as pressure, concentration, colour, density, viscosity etc., of the system remain unchanged with time. The chemical equilibrium is a dynamic equilibrium, because both the forward and backward reactions continue to occur even though it appears static externally. In physical equilibrium, the volume of all the phases remain constant.
Question 63
In Aerated soft drinks dissolved carbon dioxide in the form of______
A
Carbonic acid
B
Carboxylic acid
C
Epoxy resin
D
Hydrogen chloride
Question 63 Explanation: 
Aerated soft drinks contain dissolved carbon dioxide in a pop bottle (Soda). When the bottle is sealed, the dissolved carbon dioxide (in the form of carbonic acid) and gaseous CO2 are in equilibrium with each other. When you open the bottle, the gaseous CO2 can escape. So, the dissolved CO2 begins to un-dissolve back to the gas phase trying to replace the gas that was lost, when you opened the bottle. That’s why if you leave it open long enough, it will goes ‘flat’. All the CO2 will be gone, blown away in the air.
Question 64
The hydronium ion formed is a______ acid and the hydroxyl ion is a______ base
A
Strong, Weak
B
Weak, Weak
C
Strong, Strong
D
Weak, Strong
Question 64 Explanation: 
The hydronium ion formed is a strong acid and the hydroxyl ion is a strong base. So as fast as they are formed, they react again to produce water. Thus, it is a reversible reaction and attains equilibrium very quickly. So, the extent of ionisation is very little and the concentration of the ions produced is also very less.
Question 65
What is the value if ionic product of water?
A
1.00 × 10^-14
B
1.00 × 10^14
C
2.00 × 10^-14
D
2.00 × 10^14
Question 65 Explanation: 
The product of the concentration of the hydronium ion and the hydroxyl ion is called ‘ionic product of water’. It is denoted as ‘Kw’. It is mathematically expressed as follows: Kw = [H3 O+] [OH-] Its unit is mol^2 dm^-6. At 25° C, its value is 1.00 × 10^-14.
Question 66
Which of the following decides whether the aqueous solution is acid or base?
A
Hydrogen ion
B
Hydroxyl ions
C
Either a or b
D
None
Question 66 Explanation: 
All the aqueous solutions may contain hydrogen and hydroxyl ions due to self-ionisation of water. In addition to this ionisation, substances dissolved in water also may produce hydrogen ions or hydroxyl ions. The concentration of these ions decides whether the solution is acidic or basic.
Question 67
Match the following
  1. Acids                                              1. pH equal to 7
  2. Bases                                             2. pH greater than 7
  3. A neutral solution                    3. pH less than 7
 
A
2, 1, 3
B
2, 3, 1
C
3, 2, 1
D
1, 2, 3
Question 67 Explanation: 
Explanation pH scale is a set of numbers from 0 to 14 which is used to indicate whether a solution is acidic, basic or neutral. Acids have pH less than 7 Bases have pH greater than 7 A neutral solution has pH equal to 7 The pH is the negative logarithm of the hydrogen ion concentration. i.e. pH = –log10[H+]
Question 68
Match the following acids with their pH level:
  1. HCl (4%)                          1. 4.2
  2. Vinegar                             2. 0
  3. Human saliva                    3. 3
  4. Tomato juice                     4. 6-8
A
2, 1, 3, 4
B
2, 3, 4, 1
C
2, 4, 1, 3
D
1, 3, 4, 2
Question 69
pH scale is a scale for measuring the_____ ion concentration in a solution
A
Hydrogen
B
Hydroxyl
C
Chlorine
D
None
Question 69 Explanation: 
pH scale is a scale for measuring the hydrogen ion concentration in a solution. The 'p' in pH stands for ‘Potenz’ in German meaning 'power'. pH notation was devised by the Danish biochemist Sorensen in 1909.
Question 70
Match the following with their pH level:
  1. Blood plasma                    1. 5.6
  2. Drain cleaner                    2. 10
  3. Milk of magnesia           3. 13
  4. Coffee                               4. 7.4
A
4, 1, 2, 3
B
4, 3, 2, 1
C
2, 3, 1, 4
D
3, 1, 2, 4
Question 71
Which of the following statement is correct?
  1. The pH of a solution can be determined by using a universal indicator.
  2. It comes in the form of a solution or a pH paper
  3. The colour of the solution on the pH paper is compared with the colour chart and the pH value is read from it. Th e pH values thus obtained are only approximate values.
A
1, 2
B
2, 3
C
1, 3
D
All the above
Question 71 Explanation: 
The pH of a solution can be determined by using a universal indicator. It contains a mixture of dyes. It comes in the form of a solution or a pH paper. A more common method of measuring pH in a school laboratory is by using the pH paper. A pH paper contains a mixture of indicators. It shows a specific colour at a given pH. A colour guide is provided with the bottle of the indicator or the strips of paper impregnated with it, which are called pH paper strips. Th e test solution is tested with a drop of the universal indicator, or a drop of the test solution is put on the pH paper. The colour of the solution on the pH paper is compared with the colour chart and the pH value is read from it. The pH values thus obtained are only approximate values.
Question 72
Match the following
  1. Our body works within the pH range                   1. 7.4
  2. pH of blood is ranges b/w                         2. 7.0 to 7.8
  3. Ideal pH for blood                                     3. 7.35 to 7.45
A
2, 1, 3
B
2, 3, 1
C
3, 1, 2
D
1, 3, 2
Question 72 Explanation: 
Our body works within the pH range of 7.0 to 7.8. Living organisms can survive only in a narrow range of pH change. Different body fluids have different pH values. For example, pH of blood is ranging from 7.35 to 7.45. Any increase or decrease in this value leads to diseases. The ideal pH for blood is 7.4.
Question 73
Which acid is produced by stomach?
A
Formic acid
B
HCl
C
H2SO4
D
HOCl
Question 73 Explanation: 
It is very interesting to note that our stomach produces hydrochloric acid. It helps in the digestion of food without harming the stomach.
Question 74
What is the pH of stomach fluid?
A
2.0
B
4.2
C
3.9
D
1.0
Question 74 Explanation: 
During indigestion the stomach produces too much acid and this causes pain and irritation. pH of the stomach fluid is approximately 2.0.
Question 75
Which of the following statement is correct?
  1. pH of the saliva normally ranges between 6.5 to 7.5.
  2. White enamel coating of our teeth is calcium carbonate, the hardest substance in our body
  3. When the pH of the mouth saliva falls below 5.5, the enamel gets weathered
A
1, 2
B
2, 3
C
1, 3
D
All the above
Question 75 Explanation: 
pH of the saliva normally ranges between 6.5 to 7.5. White enamel coating of our teeth is calcium phosphate, the hardest substance in our body. When the pH of the mouth saliva falls below 5.5, the enamel gets weathered. Toothpastes, which are generally basic are used for cleaning the teeth that can neutralise the excess acid and prevent tooth decay.
Question 76
Citrus fruits require slightly____ soil
A
Acidic
B
Basic
C
Alkaline
D
Saline
Question 76 Explanation: 
In agriculture, the pH of the soil is very important. Citrus fruits require slightly alkaline soil, while rice requires acidic soil and sugarcane requires neutral soil.
Question 77
The pH of rain water is approximately_____
A
7
B
9
C
4
D
3
Question 77 Explanation: 
The pH of rain water is approximately 7, which means that it is neutral and also represents its high purity. If the atmospheric air is polluted with oxide gases of sulphur and nitrogen, they get dissolved in the rain water and make its pH less than 7. Th us, if the pH of rain water is less than 7, then it is called acid rain. When acid rain fl ows into the rivers it lowers the pH of the river water also.
Question 78
Calculate the pH of 0.01 M HNO3?
A
2
B
4
C
1
D
5
Question 79
The hydroxyl ion concentration of a solution is 1 × 10-9 M. What is the pOH of the solution?
A
10
B
11
C
9
D
2
Question 80
Which of the following is correct?
A
pH + pOH = 14
B
pH + pOH = -14
C
pH - pOH = 14
D
pH * pOH = 14
Question 80 Explanation: 
The pH and pOH of a water solution at 25 degree C, are related by the following equation. pH + pOH = 14 If either the pH or the pOH of a solution is known, the other value can be calculated.
Question 81
A solution has a pOH of 11.76. What is the pH of this solution?
A
2.24
B
3.9
C
3.7
D
4.9
Question 82
Calculate the pH of 0.001 molar solution of HCl
A
8
B
3
C
1
D
9
Question 83
What would be the pH of an aqueous solution of sulphuric acid which is 5 × 10–5 mol litre–1 in Concentration?
A
1
B
8
C
4
D
2
Question 84
If the pH of a solution is 4.5, what is its pOH?
A
8.5
B
7.5
C
4.5
D
9.5
Question 85
Calculate the pH of a solution in which the concentration of the hydrogen ions is 1.0 × 10–8 mol Litre^–1.
A
3
B
9
C
1
D
8
Question 86
Which of the following statement about reversible reaction is correct?
  1. It can be reversed under suitable conditions.
  2. It is fast.
  3. It attains equilibrium.
A
1, 2
B
1, 3
C
2, 3
D
All the above
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