Question

Temperature of an ideal gas is T K and average kinetic energy is $E = 2.07 \times 10^{- 23}$T Joule/molecule. Number of molecules in 1 litre gas at S.T.P. will be

• A. $2.68 \times 10^{22}$
• B. $2.68 \times 10^{25}$
• C. $2.68 \times 10^{28}$
• D. $1.68 \times 10^{22}$

Answer 1

Answer: (A)

$2.68 \times 10^{22}$

Answer 2

As we know that at S.T.P. 22.4 litre of gas contains $6.023 \times 10^{23}$ molecules

∴ 1 litre of gas contain $\frac{6.023 \times 10^{23}}{22.4} = 2.68 \times 10^{22}$ molecules.