Question

If an equivalent weight of an element is 32, then the percentage of oxygen in its oxide is:
A.16
B.40
C.32
D.20

Answer 1

Hint: Here we have the value of equivalent weight. The percentage of oxygen is found by the equivalent weight which value is given. The equivalent weight of an element or radical is equal to its atomic weight or formula weight divided by the valence it assumes in compounds. The unit of equivalent weight is the atomic mass unit; the amount of a substance in grams numerically equal to the equivalent weight is called gram equivalent.

Complete step by step solution:
Here we have the value of an equivalent weight which is 32. We will find the percentage of oxygen in its oxide.
The given value is as below:
Equivalent weight of an element = 32 g
Equivalent weight of an oxygen = 8 g
One Equivalent of oxide = 32+8 = 40 g
Percentage of oxygen in its oxide
$ = \dfrac{8}{{40}} \times 100$
\[ = 20\% \]

Hence, option (D) is correct.

Note: The equivalent can be thought of as the weight of a substance that will contain a single reactive proton or a single reactive hydroxide ion. The former case applies to acids, which are proton donors, while the second applies to bases, which are proton acceptors. The reason for the equivalent weight is needed is that some compounds can donate or accept more than one proton, meaning that for every mole present, the substance is in effect doubly reactive.