Question

The silver salt of a monobasic acid on ignition gave 60% of Ag. The molecular mass of the acid is
(a) 37
(b) 33
(c) 73
(d) 77

Answer 1

Hint: Let us consider the silver salt of monobasic acid as$x$. Then, find out the value of $x$ by equating it with molecular mass of Ag.

Complete step by step answer:
This is a mathematical problem. First try to understand the problem and write the question in the mathematical form and analyze what we need to find out.
Here, the acid used is monobasic in nature. It means there is only hydrogen which can be displaced from the acid.
Firstly, we can consider the amount of monobasic acid as X, an unknown quantity. Then, equate it with the molecular mass of silver which is 108.
Then, solve for x.
After getting the value of x, subtract the molecular mass of silver from the value of x. It will give you the molecular mass of the anion.
Since, the acid used is monobasic in nature. Therefore, we will add one to the molecular mass of the anion.
Thus, we get the molecular mass of the acid.
Let us consider the monobasic acid as $x$.
So, according to the question,
60% of Silver salt of Monobasic acid = Molecular mass of Silver.
\[=>\text{ 60 }\!\!%\!\!\text{ of }x\text{ = 108 (Mass of Ag)}\]
\[\text{= }\dfrac{60}{100}\text{x }x=108\]
\[\text{= x= 180}\]
Out of 180g/mol, 108 g/mol is the molecular mass of Silver (Ag)
\[\therefore \text{Molecular mass of anion = 180-108=72}\mu \]
As it is given in the question, the acid is monobasic.
\[\therefore \text{Mass of the Acid= Anion + H}\]
 \[=72+1=73\]
Hence, the correct option for the molecular mass of the silver salt of the monobasic acid is= 73$\mu $i.e. (c).

Note: It should be noted that while writing the molecular mass of silver salt, never forget to write the unit.