Question

The volume of water to be added to $50{\text{cm}}^3$ of a $0.5\text{N}HCl$ to get a decinormal solution is:

• A. $100{\text{cm}}^3$
• B. $200{\text{cm}}^3$
• C. $50{\text{cm}}^3$
• D. $400{\text{cm}}^3$

Answer 1

The correct option is B $200{\text{cm}}^3$

As per the concept of dilution,
$N_1{V}_1=N_2{V}_2$
Decinormal means that the normality $=0.1\text{N}$
$(0.5\times 50)=(0.1\times V_2)$
$V_2=250{\text{cm}}^3$
So, the volume of water added should be $(250-50)c{m}^3=200{\text{cm}}^3$