Question

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Answer 1

Answer:

7. a)14 g

b)108g

c)1260.5 grams

8

Answer 2

Ques 8.

1. 1 mole of nitrogen atom

⇒1 × mass of N

⇒1 × 14

1 mole of nitrogen atoms = 14 g

2. 4 moles of aluminium atoms

⇒ 4×27

4 moles of aluminium atoms = 108 g

3. 10 moles of sodium sulphite Na2SO3

Mass of Na2SO3

⇒2 × Mass of Na atom + 1 × Mass of S

atom + 3 × Mass of O atom

⇒2 × 23 + 1 × 32 + 3 × 16

⇒46 + 32 + 48 =126 g/mol

10 moles of Na2SO3 = 10 × 126 = 1260 g

Ques 9.

1. 32 g of oxygen gas = 1 mole

1 gram of oxygen gas = 1/32 mole

Given that 12 g of oxygen gas

No: of moles = given mass / molar

mass

= 12 / 32 = 0.375 mole

2. 18 g of water = 1 mole

1 gram of water = 1/18 mole

Given that 20 g of water

No: of moles = given mass / molar

mass

= 20 / 18 = 1.111 mole

3. 44 g of carbon dioxide = 1 mole

1 gram of CO2 = 1/44 mole

Given that 22 g of carbon dioxide

No: of moles = given mass / molar

mass

= 22 / 44 = 0.5 mole

Ques 10.

1. Mass of one mole of oxygen atoms

= 16 g

Then, the mass of 0.2 mole of oxygen

atoms.

= 0.2 x 16g = 3.2 g

2. Mass of one mole of water molecule

= 18 g

Then, the mass of 0.5 mole of water

molecules

= 0.5 x 18 g = 9 g