Question

Number of atoms present in $2.8$ liters of diatomic gas at $STP$ are

• A. $6.023\times {10}^{23}$
• B. $6.023\times {10}^{22}$
• C. $15\times {10}^{22}$
• D. $3.01\times {10}^{23}$

Answer 1

The correct option is C $15\times {10}^{22}$

For a diatomic gas $X_2$ at STP

1 mol of gas = 22.4 L

Moles of gas in 2.8 L = $\frac{2.8}{22.4}=0.125$ mole

Number of molecules = number of moles $\times N_A$

$=0.125\times 6.022\times {10}^{23}=7.52\times {10}^{22}$

One molecule contains 2 atoms in a diatomic gas

Number of atoms in $7.52\times {10}^{22}$ molecules $=2\times 7.52\times {10}^{22}=15\times {10}^{22}$