Question

The atomic mass of a certain tirvalent element is 27.The vapour density of its chloride is?

Answer 1

The element is clearly aluminium, the molecular mass of its chloride will be given by
Mass=27+3(35.5)
=133.5
Vapor density is molecular mass/2, i.e., 133.5/2=66.75

Answer 2

The vapour density of its chloride is 66.75

Atomic mass of an element is $27g,$

valency is $3$

Aluminium has atomic mass number$=27g$

Atomic number of Aluminium is $13$

so,it valency$=3(2,8,3)$

Atomic number of element is $17g$

it valency is$(2,8,7)$

mass$=35.5g/ml$

The compound is $ALCL_{3}$

mass of the compound$=(27N+3$ × $35.5)$

$=27+106.5$

$=133.5g/ml$

vapour density$=\frac{molar mass}{2}$

$=\frac{133.5}{2}$

vapour density $=66.75$