CBSC Worksheet for chapter-3 Atoms And Molecules class 9

CBSC Worksheet for chapter-3 Atoms And Molecules class 9

Worksheet For class 9

Find CBSE Worksheet for chapter-3 Atoms And Molecules class 9

CLASS-9

BOARD: CBSE

Chemistry Worksheet - 3

TOPIC: ATOMS AND MOLECULES

For other CBSE Worksheet for class 9 Science check out main page of Physics Wallah.

ATOMS AND MOLECULES

SUMMARY –

• Laws of chemical combination –
  1. Law of conservation of mass
  2. Law of constant proportion
• Dalton’s atomic theory and its drawbacks.
• Atom- definition, symbols, atomic mass.
• Molecules (of elements and compounds) molecular mass.
• Ions – cations and anions, writing the formula of compound.
• Ionic bond, covalent bond, valency, electrovalency, covalency.
• Gram atomic mass, gram molecular mass, mole concept, formula unit mass.

SECTION – 1

1. 44 g of CO₂ at NTP will occupy volume equal to –
   1. 44 mL
   2. 44 L
   3. 22.4mL
   4. 22.4 L
2. Number of molecules present in 0.18 g H₂O are –
   1. 0.18 × 6.023 × 10 ²³
   2. 18 × 6.023 × 10 ²³
   3. 6.023 × 10 ²²
   4. 6.023 × 10 ²¹
3. Which of the following sample contains the maximum number of atoms ?
   1. 1mg of C₄H₁₀
   2. 1 mg of N₂
   3. 1 mg of Na
   4. 1ml of water
4. The volume of 7g of N₂ at N.T.P. is –
   1. 11.2 L
   2. 22.4 L
   3. 5.6 L
   4. 6.5 L
5. A piece of sodium weighs 0.023 g. The number of atoms present in it are –
   1. 6.023 × 10 ²⁰
   2. 60.23 × 10 ²²
   3. 6.023 × 10 ²¹
   4. 6.023 × 10 ¹⁹
6. 4.4 g of CO ₂ and 2.24 litre of H ₂ at STP are mixed in a container. The total number of molecules present in the container will be -
   1. 6.023 x 10 ²³
   2. 1.2044 x 10 ²³
   3. 2 mole
   4. 6.023 x 10 ²⁴
7. The total number of protons , electrons and neutrons in 12g of ₆ C ¹² is –
   1. 1.084 × 10 ²⁵
   2. 6.022 × 10 ²³
   3. 6.023 × 10 ²²
   4. 18
8. Which postulate of Dalton’s atomic theory suggests the law of conservation of mass ?
   1. Atom cannot be divided.
   2. All the matter is made up of very small particles called atoms.
   3. Elements consist of atoms combined in a fixed ratio.
   4. Atoms can neither be created nor be destroyed.
9. The number of atoms present in a molecule of element is called its –
   1. molecularity
   2. atomicity
   3. valency
   4. reactivity

SECTION – 2

1. An element X has a valency of 4 whereas other element Y has a valency of 1. What will be the formula of the compound between X and Y ?
2. What is the difference between the molecule of an element and the molecule of a compound ?
3. Give one example of each.
4. What do we call particles which have –
   1. More electrons than the normal atoms ?
   2. Less electrons than the normal atoms ?
5. Name the following compounds. Also write the symbols and formulae of the ions present in them.
   1. CuSO₄
   2. (NH₄)₂SO₄
   3. Na₂O
   4. Na₂CO₃
   5. CaCl₂
6. What is the mass of 0.2 mole of oxygen atoms ?
7. Calculate the number of aluminium ions present in 0.051 g of aluminium oxide (Al₂O₃).
   [Atomic mass : Al=27u ; O=16u]
8. What weight of oxygen will contain the same number of molecules as 56 g of nitrogen gas ?
   [Atomic mass : O=16u ; N=14u]