The number of molecules in 22.4 cm3 of ozone gas at STP is ………�

1.	The number of molecules in 22.4 cm3 of ozone gas at STP is ……………….(A) 6.022 × 1020 (B) 6.022 × 1023 (C) 22.4 × 1020(D) 22.4 × 1023
Answer» (A) \(6.022 × 10^{20}\) As we know, \(1\,cm^3=1\,ml\) \(\therefore 22.4\,cm^3=22.4\,ml\) The volume of 1 mole of a gas at STP = 22400 ml/mol \(\therefore\) Number of moles of \(O_3\) gas = \(\frac{22.4\,ml}{22400\,ml/mol}\) = \(10^{-3}\) moles. \(\because\) 1 mole of \(O_3\) molecule contain = \(6.022\times10^{23}\) \(O_3\) molecules. \(\therefore 10^{-3}\) moles of \(O_3\) molecule contain = \(6.022\times10^{23}\times10^{-3}\) \(O_3\) molecules. = \(6.022\times10^{20}\) \(O_3\) molecules. Option : (A) 6.022 × 10²⁰

The number of molecules in 22.4 cm3 of ozone gas at STP is ……………….(A) 6.022 × 1020 (B) 6.022 × 1023 (C) 22.4 × 1020(D) 22.4 × 1023

Answer»

(A) \(6.022 × 10^{20}\)

As we know,

\(1\,cm^3=1\,ml\)

\(\therefore 22.4\,cm^3=22.4\,ml\)

The volume of 1 mole of a gas at STP = 22400 ml/mol

\(\therefore\) Number of moles of \(O_3\) gas = \(\frac{22.4\,ml}{22400\,ml/mol}\)

= \(10^{-3}\) moles.

\(\because\) 1 mole of \(O_3\) molecule contain = \(6.022\times10^{23}\) \(O_3\) molecules.

\(\therefore 10^{-3}\) moles of \(O_3\) molecule contain = \(6.022\times10^{23}\times10^{-3}\) \(O_3\) molecules.

= \(6.022\times10^{20}\) \(O_3\) molecules.

Option : (A) 6.022 × 10²⁰