Matter Around Us Book Back Questions 7th Science Lesson 3

7th Science Lesson 3

3] Matter Around Us

Book Back Questions with Answer and Do You Know Box Content

Do You Know?

The most abundant type of atom in the universe is the hydrogen atom. Nearly 74% of the atoms in the universe are hydrogen atoms. However on Earth the three most abundant atom are iron, oxygen and silicon.

Bismuth in diarrhea medicine: Bismuth is an element that occurs naturally. It is combined with other elements to make medicine for treating diarrhea.

The Robert Boyle is the first scientist used the term element. An early proponent of the elemental nature of matter and the nature of vacuum. He was known best for Boyle’s Law.

In the beginning, the names of elements were derived from the name of the place where they were found for the first time. For example, the name copper was taken from Cyprus. Some names were taken from specific colours. For example, gold was taken from the English word meaning yellow. Now-a-days, IUPAC approves names of elements. Many of the symbols are the first one or two letters of the element’s name in English. The first letter of a symbol is always written as a capital letter (uppercase) and the second letter as a small letter (lowercase).

How do hot-air balloons float? When air inside the hot air balloon is heated with a burner, it expands. The expansion causes the density of the air inside the balloon to decrease. Hence, the air inside the balloon has a lower density that the air outside of the balloon. This difference is density allows the hot-air balloon to float.

Choose the best answers:

1. Which of the following is an example of a metal?

(a) Iron

(b) Oxygen

(c) Helium

(d) Water

2. Oxygen, hydrogen and sulphur are examples of which of the following?

(a) Metals

(b) Non-metals

(c) Metalloids

(d) Inert gases

3. Which of the following is a short and scientific way of representing one molecule of an element or compound?

(a) Mathematical formula

(b) Chemical formula

(c) Mathematical symbol

(d) Chemical symbol

4. The metals which is a liquid at room temperature

(a) Chlorine

(b) Sulphur

(c) Mercury

(d) Silver

5. An element which is always lustrous, malleable and ductile

(a) Non-metal

(b) Metal

(c) Metalloid

(d) Gas

Fill in the blanks:

1. The smallest particle of matter that can exist by itself _____________

2. A compound containing one atom of carbon and two atoms of oxygen is _________________

3. ___________________ is the only non-metal conducts electricity.

4. Elements are made up of ______________ kinds of atoms.

5. _______________ of some elements are derived from Latin or Greek names of the elements.

6. There are ________________ number of known elements.

7. Elements are the ________________ form of pure substances.

8. The first letter of an element always written in _______________ letter.

9. Molecule containing more than three atoms is known as ______________

10. ______________ is the most abundant has in the atmosphere.

Complete the analogy:

1. Mercury: liquid at room temperature :: Oxygen: _______________

2. Non metal conducting electricity: __________________ :: Metal conducting electricity: copper

3. Elements: combine to form compounds :: compounds :: ______________

4. Atoms: fundamental particle of an element :: ___________________: fundamental particles of a compound.

State true or false. If false, correct the statement:

1. Two different elements may have similar atoms.

2. Compounds and elements are pure substance.

3. Atoms cannot exist alone; they can only exist as groups called molecules.

4. NaCl represents one molecule of sodium chloride.

5. Argon is mono atomic gas.

Answers:

Choose the best answer:

1. Iron 2. Non-metals 3. Chemical formula 4. Mercury 5. Metal

Fill in the blanks:

1. Atom 2. Carbon di oxide 3. Graphite 4. Same 5. Symbols 6. 118

7. Simplest 8. Capital 9. Polyatomic 10. Nitrogen

Complete the analogy:

1. Gas at room temperature 2. Graphite 3. Combines to form mixtures 4. Molecules

State True or False:

1. False

Correct Statement: Two different elements may not have similar atoms.

2. True

3. False

Correct Statement: Atoms can exist alone.

4. True

5. True