Chlorine molecule is a ____.

Correct! Wrong!

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A molecule of chlorine is made up of two atoms of chlorine(Cl2 ) , hence it is diatomic.

The elements present in quick lime are ____.

Correct! Wrong!

The elements present in quick lime are calcium and oxygen, it is calcium oxide and its formula is CaO.

The valency of nitrogen in ammonia is ____.

Correct! Wrong!

Ammonia is formed when one atom of nitrogen combines with three atoms of hydrogen. Therefore, the valency of nitrogen in ammonia is three.

What is the name of the compound represented by the formula CaCO3?

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Ca is the symbol of calcium and CO32−is a carbonate radical, hence, the name of the compound is calcium carbonate.

The compounds are formed by combination of atoms. This law was stated by____.

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According to Dalton's atomic theory, the compounds are formed by the combination of atoms.

How many moles are there in 12 g of oxygen gas?

Correct! Wrong!

How many moles are there in 12 g of oxygen gas?

What is the molecular mass of SO2?

Correct! Wrong!

Molecular mass of SO2 = 64

The indivisibility of atom was proposed by ____.

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According to Dalton’s atomic theory, an atom cannot be created,divided, or destroyed as a result of a chemical change.

Which of the following element forms a triatomic molecule?

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Ozone is a triatomic molecule of oxygen. In one molecule of ozone,there are three oxygen atoms.

Chemists commonly express the amount of any substance in ____.

Correct! Wrong!

Chemist express amount of a substance in moles.

The number of atoms present in a molecule of an element is called ____.

Correct! Wrong!

Atomicity is defined as the number of atoms present in one molecule of an element.

How many molecules of sulphur (S8) are there in 16 g of solid sulphur?

Correct! Wrong!

3.76×1022

The symbol of chromium is ____.

Correct! Wrong!

The symbol of chromium is Cr.

Atoms of different elements have the same mass.

Correct! Wrong!

According to Dalton’s atomic theory, atoms of different elements have different masses.

5.85 g of a compound contains 3.55 g of chlorine and 2.30 g of sodium. What will be the mass percentage of chlorine in the compound?

Correct! Wrong!

Mass % of Cl =( Mass of C/ Mass of compound) x 100 = (3.55/5.85) x 100=60.7

A molecule is made up of atoms.

Correct! Wrong!

A molecule is formed by the chemical combination of two or more atoms of same or different elements.

Mass of one Avogadro number of oxygen atoms is equal to _____.

Correct! Wrong!

1 mole = Gram atomic mass = Avogadro number

What is the atomic mass of potassium?

Correct! Wrong!

The atomic mass of potassium is 39 u.

Atomicity of sulphur is ____.

Correct! Wrong!

Atomicity of sulphur is 8. Therefore, sulphur is octa atomic.

What is the molar mass of carbon monoxide?

Correct! Wrong!

Molar mass of carbon monoxide = Mass of C + Mass of O Molar mass of carbon monoxide = = 12+16=28

How many moles are there in 0.64 g of sulphur dioxide?

Correct! Wrong!

Number of moles = Given mass/ Molecular mass Number of moles in 0.64 g of SO2 = 0.64/64 = 0.01 mole

The symbol Au represents silver.

Correct! Wrong!

The symbol Au represents gold.

Neon is mono atomic gas. What mass of neon contains 6.022 × 1023 atoms?

Correct! Wrong!

1 mole of an element = Atomic mass of the element = 6.022 × 1023 The atomic mass of neon is 20 and it has 6.022 × 1023 atoms, hence, its mass is 20 g.

What is the mass of 3 moles of aluminium?

Correct! Wrong!

Mass of 1 mole of aluminium = 27 g Mass of 3 moles of aluminium = 3 × 27= 81 g

What is the valency of phosphate ion?

Correct! Wrong!

Phosphate is a trivalent ion. Therefore, its valency is 3.

In carbon disulphide, the mass of sulphur in combination with 3 g of carbon is ____.

Correct! Wrong!

12 g of carbon combines with 64 g of sulphur to form carbon disulphide 3 g of carbon will combine with (64/12) x 3= 16 g

Modern atomic symbols are based on the method proposed by ____.

Correct! Wrong!

A Swedish chemist Berzelius introduced the first universally acceptable system of atomic symbols.

The accepted unit of atomic and molecular mass is ____.

Correct! Wrong!

The unit of atomic and molecular mass is amu or u.

A sample of ammonia weighs 2 g . What mass of sulphur dioxide contains the same number of molecules as 2g of ammonia?

Correct! Wrong!

"Mass of ammonia = Mass of nitrogen + 3 × Mass of hydrogen = 14 + 3 × 1 = 17 Number of moles in 2 g of ammonia =2 /17 Mass of sulphur dioxide = Mass of sulphur + 2 × Mass of oxygen = 32 + 2 × 16 = 64 Number of moles of sulphur dioxide = Mass of sulphur dioxide (m)/ Molecular mass of sulphur dioxide According to mole concept, equal number of moles of all substances contains the same number of molecules. m/64 = 2/17=7.53g

The value of the Avogadro’s constant is ____.

Correct! Wrong!

The value of the Avogardo’s constant is 6.022 × 1023.

CBSE Class 9th Science 3 - Atoms and Molecules MCQs
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