Question

Which of the following contains greatest number of oxygen atoms ?

• A. $1g$ of $O$
• B. $1g$ of $O_2$
• C. $1g$ of $O_3$
• D. All have the same number of atoms

Answer 1

Answer: (D)

Number of atoms $=$ moles $\times N_A\times$ atomicity

Here, $N_A=$ Avogadro's number

(a) Number of oxygen atoms in $1g$ of $O$

$=\frac{1}{16}\times N_A\times 1$

$=\frac{N_A}{16}$

(b) Number of oxygen atoms in $1g$ of $O_2$

$=\frac{1}{32}\times N_0\times 2$

$=\frac{N_A}{16}$

(c) Number of oxygen atoms in $1g$ of $O_3$

$=\frac{1}{48}\times N_A\times 3=\frac{N_A}{16}$

Hence, all have the same number of oxygen atoms.