Question

Amount of oxygen in 2.5 moles of water is *

a 30g
b 40g
c 10g
d 20g

Answer 1

As we know, one mole of each substance contains NA = 6.023 × 1023 molecules.So, 2.5 moles of water will have N = 2.5 × 6.023 × 1023 = 15 × 1023 molecules..=40g

Answer 2

Answer:

( d. ) 40 g

Explanation:

The atomic mass of oxygen is 16u.

This means that 1 mole of oxygen atoms has a mass of 16g.

Now,

1 mole of oxygen atoms = 16 g

2.5 moles of oxygen atoms = 16 × 2.5

= 40g

Hence, The mass of oxygen atoms is 40 g.

Extra information:

A group of 6.022 × 10²³ particles cations, molecules, ions of a substance is called mole.

⟼ It is also called dozen of chemistry

⟼ S.I unit of amount of substance is mole.

⟼ 6.022 × 10²³ ,is called Avagadros number or Avagadros constant.

⟼ Avagadros constant is represented by number or Na or < .