Question

One gm equivalent of a substance is present in:
(A)- 0.25 mole of \[{{O}_{2}}\]
(B)- 0.5 mole of \[{{O}_{2}}\]
(C)- 1.00 mole of \[{{O}_{2}}\]
(D)- 8.00 mole of \[{{O}_{2}}\]

Answer 1

Hint: In this, we will find the value of one gram equivalent of oxygen. Then, we can calculate the amount of mole representing the one gram equivalent of oxygen.

Complete Solution :
-First, we will define the equivalent weight. It is also known as gram equivalent i.e. the mass of a given substance which will combine with or displace a fixed quantity.

-Now, we can write the formula of
$\text{Equivalent weight}=\dfrac{\text{Molecular weight (MW)}}{n}$

here MW is the molecular weight of substance:
and n is the valency factor
-Molecular mass or molecular weight can be calculated from the summation of the atomic masses of each nuclide present in the molecule.
-n-factor is the number of electrons gained or lost by one atom of a compound. The n-factor for acid is the number of ${{H}^{+}}$ ions replaced by 1 mole of acid in a reaction. The n-factor for a base is the number of $O{{H}^{-}}$ ions replaced by 1 mole of the base in a reaction. n-factor is not equal to the acidity.

- Now in the question the mass of the entity is given in terms of gm.
-Therefore, the gram equivalent will be calculated by multiplying the given moles into the MW.

-In this question, the molecular weight of \[{{O}_{2}}=32g\]
-If we calculate the gram equivalent of \[{{O}_{2}}\], it is equal to 8 gm mass.
-For the first option, 0.25 mole of \[{{O}_{2}}=0.25\times 32=\dfrac{32}{4}=8gm\] mass
-Second option, 0.5 moles of \[{{O}_{2}}=0.5\times 32=\dfrac{32}{2}=16gm\] mass
-Third option, 1.00 mole of \[{{O}_{2}}=1\times 32=\dfrac{32}{1}=32gm\] mass
-Fourth option, 8.00 mole of \[{{O}_{2}}=8\times 32=256gm\] mass.
-By calculating the given options, 8 gm mass is represented by 0.25 mole of \[{{O}_{2}}\] .
So, the correct answer is “Option A”.

Note: Don’t get confused between the terms equivalent weight, and gram equivalent. These both are the same terms. Remember the formula to calculate the equivalent weight. The molecular weight of oxygen must be known to you.