Question

One gm equivalent of a substance is present in:

• A. 0.25 mole of ${\mathrm{O}}_2$
• B. 0.5 mole of ${\mathrm{O}}_2$
• C. 8.00 mole of ${\mathrm{O}}_2$
• D. 1.00 mole of ${\mathrm{O}}_2$

Answer 1

The correct option is A

0.25 mole of ${\mathrm{O}}_2$

Explanation for correct answers:

Option A 0.25 mole of ${\mathrm{O}}_2$

• The equivalent weight is the mass of one equivalent which is the mass of a given substance. will combine with or displace a fixed quantity of another substance.
• The formula to find the equivalent weight is $\mathrm{Equivalent}\mathrm{weight}=\frac{\mathrm{M}.\mathrm{W}}{\mathrm{n}}$.
• Where, $\mathrm{MW}$ is the molecular weight of a substance and $\mathrm{n}$ is the valency factor(number of electrons gained or lost by one atom of a compound).
• The molecular weight of Oxygen is $16\mathrm{g}$ and the valency of oxygen is 2
• Thus the equivalent weight of oxygen is $\frac{16}{2}=8\mathrm{g}$
• Mass of 0.25 mole of ${\mathrm{O}}_2$is $O_2=0.25\times 32=\frac{32}{4}=8\mathrm{gm}$.
• The $8\mathrm{g}$ mass is represented by 0.25 mole of ${\mathrm{O}}_2$, that is one gm equivalent of a substance is present in .25 mole of ${\mathrm{O}}_2$.
• Hence, Option A is correct.

Explanation for incorrect answers:

Option B 0.5 mole of ${\mathrm{O}}_2$

• The equivalent weight of oxygen is $\frac{16}{2}=8\mathrm{g}$
• Mass of 0.5 mole of ${\mathrm{O}}_2$ is $O_2=0.5\times 32=\frac{32}{2}=16\mathrm{gm}$
• Here the mass is not equal to the equivalent weight.
• Hence, Option B is incorrect.

Option C 8.00 mole of ${\mathrm{O}}_2$

• The equivalent weight of oxygen is $\frac{16}{2}=8\mathrm{g}$
• Mass of 8.00 mole of ${\mathrm{O}}_2$ is $O_2=8\times 32=256\mathrm{g}$
• Here the mass is not equal to the equivalent weight.
• Hence, Option C is incorrect.

Option D 1.00 mole of ${\mathrm{O}}_2$

• The equivalent weight of oxygen is $\frac{16}{2}=8\mathrm{g}$
• Mass of 1.00 mole of ${\mathrm{O}}_2$ is $O_2=1\times 32=\frac{32}{1}=32\mathrm{g}$
• Here the mass is not equal to the equivalent weight.
• Hence, Option D is incorrect.