Equilibrium Ques 33
33. Following solutions were prepared by mixing different volumes of $NaOH$ and $HCl$ of different concentrations :
[2018]
a. $\quad 60 $ $mL$ $ \frac{M}{10}$ $ HCl+40 $ $mL$ $ \frac{M}{10}$ $ NaOH$
b. $\quad 55 $ $mL$ $ \frac{M}{10}$ $ HCl+45 $ $mL$ $ \frac{M}{10}$ $ NaOH$
c. $\quad 75 $ $mL$ $ \frac{M}{5} $ $HCl+25 $ $mL$ $ \frac{M}{5} $ $NaOH$
d. $\quad 100 $ $mL$ $ \frac{M}{10}$ $ HCl+100 $ $mL$ $ \frac{M}{10}$ $ NaOH$
$pH$ of which one of them will be equal to 1 ?
(a) b
(b) a
(c) c
(d) d
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Answer:
Correct Answer: 33.(c)
Solution:
- (c) Meq. of $HCl=75 \times \frac{1}{5} \times 1=15$
Meq. of $NaOH=25 \times \frac{1}{5} \times 1=5$
Meq. of $HCl$ in resulting solution $=10$
Molarity of $[H^{+}]$in resulting mixture $=\frac{10}{100}=\frac{1}{10}$
$pH=-\log [H^{+}]=-\log [\frac{1}{10}]=1.0$
BETA
