Science Questions

7th Std Science Lesson Wise Questions in English – Part 2

7th Science Lesson 15 Questions in English

15] Chemistry in Daily Life

1. Which among the following is a special combination of dry salts that is mixed with safe water?

  1. ORS
  2. Antacid
  3. Penicillin
  4. All the above

Explanation

ORS (Oral Rehydration Solution) is a special combination of dry salts that is mixed with safe water. It can help to replace the fluids lost due to diarrhoea.

2. During which war in 1917 Therapy with Oral Rehydration Solution (ORS) reduced cholera death rates from 50% to 3% among thousands of refugees?

  1. Bangladesh liberation war
  2. Assam liberation war
  3. Nepal liberation war
  4. Myanmar liberation war

Explanation

During the Bangladesh liberation war, Therapy with Oral Rehydration Solution (ORS) in 1971 reduced cholera death rates from 50% to 3% among thousands of refugees.

3. Which among the following Indian doctor had to manage the shortage of saline bottles and coup up with the dehydration faced by the refuges during Bangladesh liberation war?

  1. Swaran Singh
  2. John Clemens
  3. Dilip Mahalanabis
  4. R. N. Kao

Explanation

An Indian doctor, Dilip Mahalanabis, had to manage the shortage of saline bottles and coup up with the dehydration faced by the refuges. Dr Dilip Mahalanabis showed the efficacy of ORS in cholera cases among Bangladeshi refugees (1971-72). Further field trial during the cholera epidemic in Manipur attested to its efficacy, ORS has since saved the lives of millions of children around the world.

4. In which among the following state during field trial during the cholera epidemic attested to its efficacy, ORS has since saved the lives of millions of children around the world?

  1. Kerala
  2. Manipur
  3. Nagaland
  4. Rajasthan

Explanation

The field trial during the cholera epidemic in Manipur attested to its efficacy, ORS has since saved the lives of millions of children around the world.

5. Which among the following statement is correct

  1. In the normal healthy intestine, there is a continuous exchange of water through the intestinal wall. Up to 40 litres of water is secreted and very nearly as much is reabsorbed every 24 hours. This mechanism allows the absorption of soluble metabolites into the bloodstream from digested food.
  2. However, when a person becomes sick, due to diarrhoea, water is expelled and the body is not able to retain the liquid balance. This is called as ‘dehydration’. It is not the diarrhoea that kills, but the dehydration’ resulting from the infection that kills. If more than 10% of the body’s fluid is lost death occurs.
  3. Only 1
  4. Only 2
  5. Both 1 and 2
  6. None

Explanation

In the normal healthy intestine, there is a continuous exchange of water through the intestinal wall. Up to 20 litres of water is secreted and very nearly as much is reabsorbed every 24 hours. This mechanism allows the absorption of soluble metabolites into the bloodstream from digested food.

6. In addition to water loss which among the following are lost during diarrhoea?

  1. Sodium and calcium
  2. Sodium and hydrogen
  3. Sodium and potassium
  4. Calcium and hydrogen

Explanation

In a state of diarrheal disease there is imbalance and much more water is secreted than reabsorbed causing a net loss to the body which can be as high as several litres a day. In addition to water loss, sodium and potassium are also lost.

7. Dr Dilip Mahalanabis found by adding which to the salt solution, it can be absorbed by body?

  1. Calcium
  2. Sulphide
  3. Nitrogen
  4. Glucose

Explanation

The saline bottle directly transfers water and sodium into the blood stream. However, for the saline water is administered through mouth, intestinal wall, is a not able to absorb neither water nor sodium. Dr Dilip Mahalanabis found that if glucose (sugar) is added to the salt solution, then all the three- water, sodium and glucose are absorbed by the body.

8. Only with adequate sodium concentration in the intestinal wall, water can be absorbed by it through a process known ______

  1. Conversion
  2. Osmosis
  3. Reduction
  4. All the above

Explanation

Certain concentration of sodium (Na) is needed for proper functioning of the body For, example, only with adequate sodium concentration in the intestinal wall, water can be absorbed by it through a process known as osmosis. If there is inadequate salt in the intestinal wall the body will not be able to absorb water. Through the process of osmosis, the salts and sugars pull water into your bloodstream and speed up rehydration.

9. How many level teaspoons of sugar is needed to make homely made of ORS?

  1. Two
  2. Three
  3. Four
  4. Six

Explanation

Let us see homely made of ORS, be very careful to mix 6 level teaspoons of sugar and 1/2 level teaspoon of salt dissolved in 1 litre of clean water. Too much sugar can make diarrhea worse. Too much salt can be extremely harmful to the child. Making the mixture a little too diluted (with more than 1 litre of clean water) is not harmful.

10. Which is a set of symptoms caused by excess production of acid by the gastric glands of the stomach?

  1. Ulcer
  2. Diarrhoea
  3. Constipation
  4. Acidity

Explanation

Acidity is a set of symptoms caused by excess production of acid by the gastric glands of the stomach.

11. Which among the following is produced in stomach to help digest and break down food?

  1. Hydrochloric acid
  2. Sulphuric acid
  3. Nitric acid
  4. Perchloric acid

Explanation

Your stomach naturally produces gastric or hydrochloric acid (HCl) to help digest and break down food. Acidity issues arise when there is excess production of this acid due to triggers such as acidic foods, spicy food, alcohol, dehydration and stress. When acidity occurs, the excess acid may move up from your stomach to your oesophagus.

12. What is the PH of lining of the stomach which is designed as such to withstand a high acidic environment?

  1. 1 to 2
  2. 1 to 3
  3. 1 to 4
  4. 1 to 5

Explanation

The lining of your stomach with a pH of 1 to 3 is designed as such to withstand a high acidic environment.

13. When we have acidity or heartburn, we are administered a class of medicines known as ________

  1. Paracetamol
  2. Calpol
  3. Dolo
  4. Antacid

Explanation

When we have acidity or heartburn, we are administered a class of medicines known as antacids. They are actually weak bases. As learned in chemistry, when a base is mixed with an acid a neutralization reaction occurs. When antacids are consumed, it creates a chemical reaction in the stomach lowering the acidity and makes the digestive acids less corrosive and damaging.

14. Which among the following is not the antacids?

  1. Calcium Carbonate
  2. Aluminium Hydroxide
  3. Formic Hydroxide
  4. Magnesium Carbonate

Explanation

Most of the common antacids are Sodium Bicarbonate (NaHCO3), Calcium Carbonate (CaCO3), Magnesium Hydroxide (Mg (OH)2), Magnesium Carbonate (MgCO3) and Aluminium Hydroxide

Al (OH)3. The chemical reaction created when Magnesium Hydroxide neutralizes HCI in the stomach and intestine

15. Who among the following discovered antibiotics in 1928?

  1. Louis Plaster
  2. Robert Koch
  3. Alexander Fleming
  4. Howard Florey

Explanation

The discovery of antibiotics was an accident, which happened in 1928 while a British bacteriologist, Dr Alexander Fleming.

16. On researching which among the following bacteria Dr Alexander Fleming discovered Fleming?

  1. Staphylococcus
  2. Anthracis
  3. Chlamydia Tetani
  4. Pasteurella

Explanation

Dr Alexander Fleming was involved in research on staphylococcus bacteria, he developed antibiotics. This bacterium was meant to cause deadly diseases such as pneumonia, sour throat, etc.

17. Which among the following statement was correct

  1. The discovery of antibiotics happened while Alexander Fleming was culturing the bacteria on a nutrient agar media in a Petri dish. He went on a holiday carelessly leaving the dish in his laboratory table without cleaning and sterilization. After several days, when he returned back, he observed the growth of mould (kind of common fungus, which grows on stale bread/ cheese) on a part of the Petri dish.
  2. He also observed that there was no bacterial growth surrounding the mould, which indicated that something in the mould had prevented the growth of bacteria in the culture medium. On further research, Fleming identified that the “mould juice” was capable of killing a wide variety of harmful bacteria.
  3. Ages ago, there was a time where even a small infected wound can cause death in human beings. The discovery of antibiotics changed all. Now armed with antibiotics, many deadly infectious diseases can be tackled, which once meant to cause serious illness and death.
  4. Both 1 and 2
  5. Both 1 and 3
  6. Both 2 and 3
  7. All 1, 2 and 3

18. Fleming identified that the “mould juice” was capable of killing which among the following harmful bacteria?

  1. Streptococcus
  2. Meningococcus
  3. Diphtheria Bacillus
  4. All the above

Explanation

Fleming identified that the “mould juice” was capable of killing a wide variety of harmful bacteria, such as streptococcus, meningococcus and diphtheria bacillus.

19. Which was the world first antibiotics discovered by Alexander Fleming?

  1. Paracetamol
  2. Penicillin
  3. Aspirin
  4. Codeine

Explanation

The world first antibiotics is penicillin discovered by Alexander Fleming.

20. Who among the following used had used mouldy bread to treat infected wounds thousands of years ago?

  1. Egyptians
  2. Greeks
  3. Serbians
  4. All the above

Explanation

Fleming was not the first using moulds and other living micro-organisms to treat infections. Thousands of years ago, the ancient Egyptians, had used mouldy bread to treat infected wounds. Similar practices were observed among ancient Greeks, Serbians and even among Indians. While these were perhaps partially effective, their efficacy is nowhere near the modern antibiotics.

21. What was the name given to the mould by Fleming?

  1. Penicillium tularensis
  2. Penicillium typhi
  3. Penicillium rattus
  4. Penicillium notatum

Explanation

Fleming named the mould penicillium notatum, from which the antibiotic penicillin was isolated.

22. Which among the following is not the antibiotics isolated from the plants/micro-organisms and used as medicines against infectious diseases?

  1. Chloramphenicols
  2. Chlorpheniramine
  3. Tetracyclines
  4. Cephalosporin

Explanation

Naturally, many micro-organisms and plants synthesize chemicals which are toxic in nature to protect them from invading organisms. The biosynthesized chemicals isolated from the plants/micro-organisms and used as medicines against infectious diseases. These substances were called as antibiotics. Ex: Chloramphenicols, tetracyclines, Penicillin derivatives, cephalosporin’s and their derivatives. Today, many infectious diseases in the world are rare due to the advancement in research.

23. Which among the following statement is correct

  1. Antibiotics work effectively for viruses like cold and the flu. The over use of antibiotics makes it inactive or less effective. Antibiotic resistance is defined as the ability of the microorganisms to resist the effects of an antibiotic to which they were once sensitive.
  2. Thus, the antibiotics become less effective and we are forced to either consume a larger dose or shifting towards the use of other virulent variants of antibiotics. Thus, the research on antibiotics is of great importance to combat the virulent and mutated microorganisms.
  3. Only 1
  4. Only 2
  5. Both 1 and 2
  6. None

Explanation

Antibiotics don’t work for viruses like cold and the flu. The over use of antibiotics makes it inactive or less effective. Antibiotic resistance is defi ned as the ability of the microorganisms to resist the effects of an antibiotic to which they were once sensitive.

24. Which among the following statement is correct

  1. Injury, burn, pressure from sharp objects and other conditions cause pain in our body. The unpleasant feeling may be a burning sensation in the tissue around the injury, throbbing headache or ache of arthritis. Back pain, neck pain, joint pain, headaches, pain from nerve damage, pain from an injury and pain related to diseases are some of the most common pains.
  2. The unpleasant emotion of ‘pain’ is created in the brain and not at the spot of the injury. If the pain is severe, say from burn, the impulse sent to brain trigger immediate response. Reacting to the signal from the brain, muscle pull our hand from the fire. Reacting to the message received from the pain spot, the brain sends back messages that initiate healing process.
  3. Only 1
  4. Only 2
  5. Both 1 and 2
  6. None

25. Which among the following was released by brain addition to release of pain suppressing chemicals by triggering?

  1. Platelets
  2. Melanin
  3. Keratin
  4. All the above

Explanation

Brain can trigger to release pain suppressing chemical and additional flow of additional white blood cells and platelets to help repair tissue at an injury site.

26. Which are the pain suppressing chemicals released by the body?

  1. Analgesics
  2. Antipyretic
  3. Histamines
  4. All the above

Explanation

Analgesics or pain killers are the pain suppressing chemicals released by the body. They suppress the feeling of ‘pain’. These analgesics drug selectively relieves pain by acting either in CNS (Central Nerves System) or on peripheral pain mechanism, without significantly altering consciousness.

27. Paracetamol interact with the receptors and reduce the intensity of pain signals to the brain, also suppresses the release of substances, called ________

  1. Dopamine
  2. Prostaglandins
  3. Serotonin
  4. Endorphins

Explanation

When we are affected by fever, often we are administered Paracetamol. Paracetamol interact with the receptors and reduce the intensity of pain signals to the brain, also suppresses the release of substances, called prostaglandins that increase pain and body temperature.

28. Which was the first local anaesthetic?

  1. Cocaine
  2. Procaine
  3. Tolycaine
  4. Articaine

Explanation

The first local anaesthetic was cocaine was isolated from coca leaves.

29. Who isolated cocaine from coco leaves in 1860?

  1. Franz Betz
  2. Albert Nieminen
  3. Heinrich Vogl
  4. Max Alvary

Explanation

Th e first local anaesthetic was cocaine was isolated from coca leaves by Albert Nieminen Germany, 1860.

30. Traditional anti-inflammatory agents can be classified into how many types?

  1. Two
  2. Three
  3. Four
  4. Six

Explanation

Traditional anti-inflammatory agents are classified into two types. i) Non – narcotic and ii) Narcotic drugs.

31. Which among the following is not the narcotics grugs?

  1. Codeine
  2. Aspirin
  3. Opium
  4. Morphine

Explanation

Non – narcotic (Non – additive) analgesics E.g., Aspirin.

32. Which among the following is not the Non-narcotic?

  1. Aspirin
  2. Ibuprofen
  3. Diclofenac
  4. Carfentanil

Explanation

Carfentanil is a narcotic drug.

33. What is the range of our body temperature in normal course?

  1. 98.4 to 98.6 degrees Fahrenheit
  2. 101.2 to 102.8 degrees Fahrenheit
  3. 104.4 to 104.8 degrees Fahrenheit
  4. 88.4 to 89.2 degrees Fahrenheit

Explanation

In normal course our body temperature is ranges from 98.4 to 98.6 degrees Fahrenheit. When the temperature goes above this level it is called fever. Most common cause of fever is infection. Bacteria and virus cannot thrive above a certain temperature. To defend the invading virus and bacteria the immunity system increases the body temperature.

34. Once infection is sensed; the immune system releases a chemical called _____

  1. Cortisol
  2. Progesterone
  3. Pyrogen
  4. Estrogen

Explanation

Once infection is sensed, the immune system releases a chemical called pyrogen. These pyrogens released into bloodstream reaches the hypothalamus, present at the basal part of the brain. The function of Hypothalamus is to control the body temperature.

35. Sensing the pyrogens, hypothalamus increases the body temperature by releasing a chemical called __________

  1. Dopamine
  2. Oxytocin
  3. Glutamate
  4. Prostaglandin

Explanation

Sensing the pyrogens, hypothalamus increases the body temperature by releasing a chemical called prostaglandin.

36. Which among the following is the maximum internal body temperature above which, this may cause damage to our body protein and the brain may experience seizures and delirium?

  1. 980 F
  2. 1010 F
  3. 1030 F
  4. 1050 F

Explanation

Normally little fever is good as it helps to arrest the growth of infection. However, if the internal body temperature exceeds 105°F, this may cause damage to our body protein and the brain may experience seizures and delirium. The prolonged high fever may also cause death.

37. Which are chemical substances that reduce fever that suppress the release of prostaglandin and reduce fever?

  1. Antihistamine
  2. Antiseptic
  3. Antipyretic
  4. All the above

Explanation

Antipyretics (anti – against and pyretic -Feverish) are chemical substances that reduce fever. They suppress the release of prostaglandin and reduce fever.

38. Which among the following is not the Antipyretic?

  1. Diphenhydramine
  2. Paracetamol
  3. Ibuprofen
  4. Aspirin

Explanation

The most common and well known anti pyretic is paracetamol. Other antipyretics and anti-inflammatory agents include Aspirin, Ibuprofen, Diclofenac.

39. Which are substances applied to the exterior of a body that kill or inhibit microbes and infective agents?

  1. Antihistamine
  2. Antiseptic
  3. Antipyretic
  4. All the above

Explanation

Antiseptics are substances applied to the exterior of a body that kill or inhibit microbes and infective agents. Antiseptics can be effective against one or a combination of bacteria, fungi, viruses or other microorganisms.

40. Which among the following is the natural anti septic?

  1. Garlic
  2. Turmeric
  3. Aloevera
  4. All the above

Explanation

Natural antiseptics are 1. Garlic, 2. Turmeric 3. Aloevera. All antiseptic are disinfectants but not all disinfectants are not antiseptic. Antiseptic can be applied on the live tissues, where disinfectants can be applied on in animate object.

41. Which among the following is not in the mixture of Dettol?

  1. Chloroxylenol
  2. Terpincol
  3. Boric acid
  4. None of the above

Explanation

Dettol is Mixture of chloroxylenol and terpincol.

42. Which among the following is not the ingredient of Tincher?

  1. Iodoform
  2. Boric acid
  3. Ethanol
  4. None of the above

Explanation

Tincher ingredients are Iodine + 2 to 3% alcohol – Water mixture Soap, Iodoform, phenolic solutions, ethanol, Boric acid, are examples.

43. Which among the following statement is correct

  1. Anti-histamines are defined as drugs that combat the histamine in the body that are used for treating allergic reactions and cold symptoms. Histamine is a chemical messenger involved in number of complex biological reactions.
  2. When a foreign body such as pollens enters the body, the immune system believes those substances to be harmful and generates the release of histamine. When histamine is released, it will interact with the histamine receptors on the cell surface or within a target cell and cause changes in the bodily functions.
  3. This stimulates many hard muscles to expand, such as Soleus and Gastrocnemius. In certain hard muscles, they cause relaxation of blood capillaries which normalise the flow of lymph and its protein content and lead to the formation of edema (redness and rashes).
  4. Both 1 and 2
  5. Both 1 and 3
  6. Both 2 and 3
  7. All 1, 2 and 3

Explanation

This stimulates many smooth muscles to contract, such as gastrointestinal tract and bronchi. In certain smooth muscles, they cause relaxation of blood capillaries which increase the flow of lymph and its protein content and lead to the formation of edema (redness and rashes).

44. Which among the following is not the Antihistamine?

  1. Diphenhydramine
  2. Chlorpheniramine
  3. Cimetidine
  4. Tetracyclines

Explanation

Antihistamines or histamine receptor antagonists oppose selectively all the pharmacological effects of histamines. For, Ex. Diphenhydramine, chlorpheniramine, cimetidine. The adverse effects of antihistamines are mouth dryness and sleepiness.

45. How many ways are there to the intake of medicine?

  1. Two
  2. Three
  3. Four
  4. Six

Explanation

The science or practice of the diagnosis, treatment, and prevention of disease. There are many ways to intake the medicine. 1. Oral use 2. External use 3. Injections (Intra muscular/Intra venous).

46. Which is a chemical reaction that occurs in the presence of a fuel and an oxidizing agent that produces energy, usually in the form of heat and light?

  1. Reduction
  2. Ionisation
  3. Combustion
  4. All the above

Explanation

Can you guess what is common in rusting or iron, burning coal and the flame of candle? They all undergo a chemical reaction known as combustion. Combustion is a chemical reaction that occurs in the presence of a fuel and an oxidizing agent that produces energy, usually in the form of heat and light.

47. Any reaction that involves reaction with oxygen is called ____

  1. Oxymoron
  2. oxidation
  3. oxical
  4. All the above

Explanation

What we call as ‘burning’ is really a combustion reaction. In fact, combustion is one of the first chemical reactions intentionally harnessed by humans. Any reaction that involves reaction with oxygen is called oxidation reaction.

48. Which among the following is the correct equation for combustion of hydrocarbon with oxygen, typically carbon dioxide and water are produced?

  1. CH4+2O2 → CO2+2H2O+Heat energy
  2. CH3+O2 → CO+H3O+Heat energy
  3. CH4+O2 → CO+H4O+Heat energy
  4. CH3+2O2 → CO3+2HO+Heat energy

Explanation

In the combustion of hydrocarbon with oxygen, typically carbon dioxide and water are produced. CH4+2O2 → CO2+2H2O+Heat energy.

49. When a combustion reaction releases heat, the reactions are called _____

  1. Exothermic
  2. Endothermic
  3. Both exothermic and endothermic
  4. None of the above

Explanation

All combustion reactions are exothermic; that is they release heat.

50. The minimum temperature at which a substance catches fire and burns is called ____

  1. Flash point
  2. Ignition temperature
  3. Combustion temperature
  4. Closure temperature

Explanation

The minimum temperature at which a substance catches fire and burns is called its ignition temperature. A substance will not catch fire and burn if its temperature is lower than its ignition temperature. Different substances have different ignition temperatures.

51. Substances which have very low ignition temperature and can easily catch fire with a flame are called ______

  1. Combustible substance
  2. Inflammable substance
  3. Projectile substance
  4. Volatile substance

Explanation

Substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances. E g. Petrol. Alcohol, LPG (Liquefied Petroleum Gas), CNG (Compressed Natural Gas), etc.

52. Which is a zone of combustions of a combustible substance which vaporize during burning?

  1. Light
  2. Flame
  3. Oxygen
  4. Heat

Explanation

Flame is a zone of combustions of a combustible substance. Substances which vaporize during burning produce flames.

53. Which mong the following statement is incorrect

  1. Flame is actually a chemical reaction. To be specific, the flame is a mixture of gases (vaporized fuel, oxygen, carbon dioxide, carbon monoxide, water vapor, and many volatile materials) and so is matter. The light and heat produced by the flame is matter, not energy. But fire is energy.
  2. A candle flame is caused by vapour burning above the candle. This burning vapour is hotter than the surrounding air and is therefore high dense. So, by the principle of reduction, it “rises” so the flame is always upwards.
  3. Only 1
  4. Only 2
  5. Both 1 and 2
  6. None

Explanation

Flame is actually a chemical reaction. To be specific, the flame is a mixture of gases (vaporized fuel, oxygen, carbon dioxide, carbon monoxide, water vapor, and many volatile materials) and so is matter. The light and heat produced by the flame is energy, not matter. But fire is a matter.

A candle flame is caused by vapour burning above the candle. This burning vapour is hotter than the surrounding air and is therefore less dense. So, by the principle of convection, it “rises” so the flame is always upwards.

54. Which among the following do not produce flames?

  1. Wax
  2. Kerosene
  3. Coal
  4. None of the above

Explanation

Substances which do not vaporize during burning do not produce flames e g. coal. Wax and Kerosene produce flame.

55. Match the following salts correctly with its flame colour?

  1. Epsom salt – 1. Violet flame
  2. Lithium Chloride – 2. Green flame
  3. Bleaching powder – 3. White flame
  4. Borax powder – 4. Blue flame
  5. Calcium chloride – 5. Yellow flame
  6. 1 – 3 – 2 – 5 – 4
  7. 3 – 1 – 4 – 2 – 5
  8. 2 – 5 – 3 – 1 – 2
  9. 4 – 1 – 2 – 5 – 1

Explanation

White flame – Epsom salt (MgSO4 ) • Violet flame – Lithium Chloride • Blue flame – Bleaching powder • Green flame – Borax powder • Yellow flame – Calcium chloride.

56. Which among the following statement is correct regarding candle flame

  1. The outer zone: partial combustions of the fuel take place and the colour of the flame is yellow and is moderately hot part of the flame. It is the luminous part of the flame.
  2. The middle zone: complete combustion of the fuel takes place and the colour of the flame is blue and is the hottest part of the flame. It is the non-luminous part of the flame.
  3. The inner zone: There are unburnt vapours of the fuel and the colour is black and is least hot part.
  4. Only 1
  5. Only 3
  6. Both 1 and 2
  7. Both 2 and 3

Explanation

The outer zone – complete combustion of the fuel takes place and the colour of the flame is blue and is the hottest part of the flame. It is the non-luminous part of the flame.

The middle zone -partial combustions of the fuel takes place and the colour of the flame is yellow and is moderately hot part of the flame. It is the luminous part of the flame.

57. The amount of heat energy produced on complete combustion of 1kg of fuel is called its _________

  1. Thermal value
  2. Burner value
  3. Calorific value
  4. Toaster value

Explanation

The amount of heat energy produced on complete combustion of 1kg of fuel is called its calorific value.

58. What will be the colour of flame if table salt soaked in alcohol and makes fire?

  1. Green flame
  2. White flame
  3. Orange flame
  4. Pink flame

Explanation

Table salt produce orange flame if soaked in alcohol and makes fire.

59. The calorific value of a fuel is expressed in a unit called _________

  1. J / kg
  2. KJ / kg
  3. KJ Kg
  4. Kg / J

Explanation

The calorific value of a fuel is expressed in a unit called kilo joule per kg (kJ/kg).

60. Which among the following equation is correct regarding calorific value?

  1. Calorific value = Amount of fuel used for burning in kJ/kg / Heat produced
  2. Calorific value = Heat produced / Amount of fuel used for burning in kJ/kg
  3. Calorific value = Amount of fuel used for burning in kJ/kg × Heat produced
  4. Calorific value = Amount of fuel used for burning in kJ/kg – Heat produced

Explanation

Calorific value = Amount of fuel used for burning in kJ/kg × Heat produced.

If 4.5kg of fuel is completely burnt and the amount of heat produced stands measured at 1, 80,000 kJ what is its calorific value. Calorific value = 1, 80,000 / 4.5 = 40,000 KJ/Kg.

61. What will be the colour of flame if Strontium chloride soaked in alcohol and makes fire?

  1. Red
  2. Indigo
  3. Blue
  4. Green

Explanation

Strontium chloride produce red flame if soaked in alcohol and makes fire. Potassium Chloride produce Indigo Flame.

62. Which among the following is not the types of combustion?

  1. Rapid combustion
  2. Cold combustion
  3. Spontaneous combustion
  4. None of the above

Explanation

There are three main types of combustion. They are, 1. Rapid combustion, 2. Spontaneous combustion and 3. Explosion.

63. Which among the following statement is correct

  1. Rapid combustion: It is a combustion process in which a substance burns rapidly and produces heat and light with the help of external heat. E.g. Burning of LPG.
  2. Spontaneous combustion: Is combustion process in which a light with the help of external heat.eg. Phosphorus burns spontaneously at high temperature.
  3. Explosion: It is a type of combustion in which a substance burns suddenly and produces heat, light and sound with the help of heat or pressure. E.g. Explosion of crackers.
  4. Both 1 and 2
  5. Both 1 and 3
  6. Both 2 and 3
  7. All 1, 2 and 3

Explanation

Spontaneous combustion: Is combustion process in which a light without the help of external heat.eg. Phosphorus burns spontaneously at room temperature.

64. Which among the following has the highest calorific value?

  1. Kerosene
  2. Biogas
  3. Petrol
  4. Methane

Explanation

Methane (500000) has highest calorific value followed by diesel (450000) and hydrogen (150000).

65. Which among the following is not the Characteristics of good fuel?

  1. Cheap
  2. Produce large amount of heat
  3. Easy transport and store
  4. Leave behind undesirable substances

Explanation

Characteristics of good fuel are 1. Readily available 2. Cheap 3. Easy transport and store 4. Burns at moderate rate 5. Produce large amount of heat 6. Do not leave behind any undesirable substances. And 7. Does not cause pollution.

66. Respiration is an example of which combustion?

  1. Slow combustion
  2. Spontaneous combustion
  3. Rapid combustion
  4. None of the above

Explanation

Slow combustion is a form of combustion which takes place at low temperatures. Respiration is an example of slow combustion.

67. Which among the following is not the condition necessary for producing fire?

  1. Fuel
  2. Air (to supply oxygen)
  3. Heat (to raise the temperature of the fuel beyond its ignition temperature)
  4. None of the above

Explanation

Th e conditions necessary for producing fire are, 1. Fuel 2. Air (to supply oxygen) and 3. Heat (to raise the temperature of the fuel beyond its ignition temperature). Fire can be controlled by removing any one or more of these conditions.

68. Which among the following fuel has the lowest calorific value?

  1. Wood
  2. Cow dung cake
  3. Petrol
  4. Biogas

Explanation

69. Which among the following statement is correct

  1. A fire extinguisher cut off the supply of Air or bring down the temperature of the fuel or both and controls the fire. Portable fire extinguishers apply an extinguishing agent that will either cool burning fuel, displace or remove oxygen, or stop the chemical reaction so fire cannot continue to burn.
  2. When the candle of an extinguisher is compressed, it opens and inner canister of high-pressure gases forces the extinguishing agent from the main cylinder through a siphon tube and out the nozzle. A fire extinguisher works much like a can of hair spray.
  3. Only 1
  4. Only 2
  5. Both 1 and 2
  6. None

70. Which among the following is not the common types of fire extinguishers?

  1. Sand soluble extinguisher
  2. Air pressurized water extinguishers
  3. Carbon-di-oxide extinguishers
  4. Dry chemical powder extinguishers

Explanation

The most common types of fire extinguishers are, 1. Air pressurized water extinguishers, 2. Carbon-di-oxide extinguishers and 3. Dry chemical powder extinguishers.

71. Which among the following is not the combustible materials?

  1. Wood
  2. Paint
  3. Paper
  4. Fabric

Explanation

Combustible materials: caused by flammable solids, such as wood, paper, and fabric.

72. Which among the following is not the Flammable gases?

  1. Hydrogen
  2. Butane
  3. Potassium
  4. Methane

Explanation

Flammable gases: like hydrogen, butane or methane.

73. Which among the following is not the Flammable liquid?

  1. Petrol
  2. Magnesium
  3. Paint
  4. None of the above

Explanation

Flammable liquids: such as petrol, turpentine or paint.

74. Fire extinguishers can be broadly classified into how many types?

  1. Two
  2. Three
  3. Four
  4. Five

Explanation

Fire extinguishers can be broadly classified into five types: 1. Water, 2. Foam, 3. Dry Powder, 4. CO2, 5. Wet Chemical.

75. Which among the following is not combustible metals?

  1. Magnesium
  2. Aluminium
  3. Potassium
  4. None of the above

Explanation

Combustible metals: chemicals such as magnesium, aluminium or potassium.

76. Which among the following class of fire is wrongly matched?

  1. Class A – Combustible materials
  2. Class B – Flammable gases
  3. Class C – Flammable liquids
  4. Class D – Combustible metals
  5. Both 1 and 2
  6. Both 1 and 3
  7. Both 2 and 3
  8. Both 3 and 4

Explanation

There are five classes of fire: Class A, Class B, Class C, Class D, and Class E.

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