Question

$5.6$ litre of oxygen at STP contains how many oxygen atoms:

• A. $1.505\times {10}^{23}$ atoms
• B. $3.01\times {10}^{23}$ atoms
• C. $6.022\times {10}^{23}$ atoms
• D. None of these

Answer 1

The correct option is

C

$3.01\times {10}^{23}$ atoms

22.4 litres of gas indicates 1mole.

5.6 litres of the gas indicates 0.25 moles.

1mole of O₂ gas contains 2 x Avogadro number of atoms of oxygen.

so,

0.25 moles of O₂ contains →0.25 x 2 x Avogadro number of atoms of oxygen

→0.5 x 6 x 10²³ oxygen atoms

→3 x 10²³ oxygen atoms

∴ 5.6 litres of Oxygen gas contains 3 x 10²³ oxygen atoms.