Question

Which of the following molarity values of ions in a aqueous solution of $5.85 \%\, w / v \,NaCl , 5.55\, \% \,w / v \,CaCl _{2}$ and $6 \% \,w / v \,NaOH$ are correct $[ Na =23, Cl =35.5$ $Ca =40=16]$

• A. $\left[ Cl ^{-1}\right]=2 M$
• B. $\left[ OH ^{-}\right]=1.5 M$
• C. $\left[ Ca ^{2+}\right]=0.5 M$
• D. All of these

Answer 1

Answer: (D)

Only single solution have all these

Means $100\, ml$ solution have $5.85\, gm\, NaCl =0.1$ mole

and $5.55\, gm \,CaCl _{2}=0.05$ mole

$\left[ Cl ^{-}\right]=\frac{(0.1+0.05 \times 2) \times 1000}{100}=2 M$

$\Rightarrow \left[ Na ^{+}\right]=\frac{(0.1+0.15) \times 1000}{100}=2.5 M$

$\left[ Ca ^{2+}\right]=\frac{0.05}{100} \times 1000=0.5 M$

$ \Rightarrow \left[ OH ^{-}\right]=1.5 \,M$