Question

47. A compound contains 28% of nitrogen and 72% of a metal by weight. Three atoms of the metal
combine with two atoms of nitrogen. Find the equivalent weight of the metal.
(a) 12 (b) 24 (c) 36 (d) 48

Answer 1

the molecular mass of nitrogen is 14
and given that it is 28% by weight
let the weight of compound be x 
therefore weight of nitrogen=$\frac{28}{100}x$
now given that there are two atoms of nitrogen
i.e.$\frac{ \frac{28x}{100} }{14}=2 \\ x=100$ 
now let the molecular mass of metal be M
given that metal is 72% by weight
therefore weight of metal=$\frac{72x}{100} \\ =\frac{72*100}{100} \\ =72$
now given that there are three atoms of metal
i.e. $\frac{72}{Z}=3 \\ Z=24$ 
now,equivalent weight =$\frac{molecular mass}{charge}$
there are two charge on metal
therefore,Equivalent weight of metal=$\frac{24}{2}$
                                                   =12 ans....................

Answer 2

(a) 12 is  the equivalent weight of the metal.