Question

$0.59\, g$ of the silver salt of an organic acid (molar mass $210$) on ignition gave $0.36 \,g$ of pure silver. The basicity of the acid is

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

Answer: (B)

$\underset{\text { Acid }}{ H _{ n }} \times \xrightarrow[{AgNO_3}]{NH_3} \underset{\text{Ag salt}}{AgN} \times \xrightarrow{\Delta} \underset{Ag}{nAg}$
$M-n \times \underset{w_{19}}{1}+n \times 108$
$n \times \frac{ w _{1}}{ m - n \times 1+ n \times 108} \frac{ W }{108} g$
Given:
$W _{1}=0.59\, g$
$W _{2}=0.36\, g$
$m =210$
$M =\frac{ n \times w _{1} \times 108}{ w _{2}}-107\, n$
$210=\frac{ n \times 0.59 \times 108}{0.36}-107\, n$
$\therefore 210=177\, n -107\, n$
$\therefore n =3$