Calculation of Molecular Weight

Let the molecular weight of the element be x.

The oxide of the element contains 67.67% oxygen, which means that the remaining 32.33% is the element.

Therefore, the ratio of the element to oxygen in the oxide is:

32.33 / 16 = 2.02

This means that the formula of the oxide is xO2.

The vapour density of the volatile chloride is 79, which means that its molecular weight is 2 x 79 = 158.

Calculation of Equivalent Weight

The equivalent weight of the element is the molecular weight divided by the valency.

The valency of the element can be determined from the formula of the oxide, which is xO2.

The valency of oxygen is 2, so the valency of x is:

2 / 2 = 1

Therefore, the equivalent weight of the element is:

x / 1 = x

Now, we can equate the molecular weight and the equivalent weight:

x = 158 / E

where E is the equivalent weight.

Solving for E, we get:

E = 158 / x

Substituting xO2 for the formula of the oxide, we get:

E = 158 / (xO2 / 2)

E = 316 / xO2

Substituting 4 for xO2, we get:

E = 316 / 4

E = 79

Therefore, the equivalent weight of the element is 79.

Calculation of Atomic Weight

The atomic weight of the element is the equivalent weight multiplied by the valency.

The valency of the element is 1, so the atomic weight is:

79 x 1 = 79

Therefore, the atomic weight of the element is 79.

Calculation of Molecular Weight

The molecular weight of the element is twice its atomic weight, because its oxide is xO2.

Therefore, the molecular weight of the element is:

2 x 79 = 158

Therefore, the equivalent weight of the element is 79 and the molecular weight is 158.

Calculation of Equivalent Weight

The equivalent weight of the element is the molecular weight divided by the valency.

Since the element has a valency of 1, the equivalent weight is equal to its atomic weight.

Therefore, the equivalent weight of the element is 79.

Answer: B) 3.82

100 g of the oxide will contain 67.67 g of oxygen and 32.33 g of the element.

Equivalent weight of an element is its weight which reacts with 8 gm of oxygen to form oxide.

67.67 g of oxygen combines with 32.33 g of the element to form oxide.

1 g of oxygen will combine with 67.6732.33​ g of element to form oxide.

8 g of oxygen will combine with 8×67.6732.33​=3.82 g of element to form oxide.

Hence, the equivalent weight of the element is 3.82.