Question

When equal volumes of two liquids are mixed,the specific gravity of mixture is $\frac{7}{2}$. When equal masses of the same two liquids are mixed, the specific gravity is $\frac{12}{7}$. The specific gravities of two liquids are:

• A. $1$ and $6$
• B. $2$ and $6$
• C. $2$ and $4$
• D. $3$ and $6$

Answer 1

The correct option is A $1$ and $6$

Let the density of liquid 1 be a

Let the density of liquid 2 be b.

Now, In 1st case ,

$\frac{va+vb}{2v}=\frac{7}{2}$

$a+b=7$ ...............(1)

In 2nd case,

$=\frac{2m}{\frac{m}{a}+\frac{m}{b}}=\frac{12}{7}=\frac{1}{a}+\frac{1}{b}=\frac{7}{6}$.....................2

from 1 and 2, $a=1$ and $b=6$.