Question

The volume of mercury and water is $50ml$ each.What is the ratio of their mass,if their densities are in the ratio $68:5$.?

• A. 8d:7
  
• B. 6d:5
• C. 7d:6
  
• D. 5d:5
  

Answer 1

The correct option is B 6d:5

For mercury
mass or mercury $=mm$
density $=dm$
Volume $=vm$
for water
mass of water $=mw$
density $=dw$
volume $=vw$
given $vm=vw$
we know that
density $=\frac{mass}{volume}$
for mercury $dm=\frac{mm}{vm}$....(i)
For water $dw=\frac{mw}{vw}$......(ii)
$\left(i\right)$ divide by $\left(ii\right)$
$\frac{dm}{dw}=\frac{mm}{mw}$
as $vm=vw$
$\frac{mm}{mw}=\frac{68}{5}=6d:5.$