Question

A trivalent metal has its equivalent mass 12 . The moleculer mass of the metal hydroxide is.

A 87 u
B63u
C 55 u
D 41u

Answer 1

Answer : The molar mass of metal hydroxide will be 87 u.

Solution : Given,

Equivalent mass = 12 g/eq

Valency of trivalent metal element = 3

Molar mass of hydroxide = 17 g/mole

The molecular formula of trivalent metal oxide is, $M(OH)_3$

Formula used :

Molar mass of an element = Equivalent mass × Valency

Now put all the given values in this formula, we get

Molar mass of an element = 12 × 3 = 36

Now we have to calculate the molar mass of $M(OH)_3$

Molar mass of $M(OH)_3=(36)+(3\times 17)=87u$

Therefore, the molar mass of metal hydroxide will be 87 u.