Question

$20mL$ of $0\cdot 5NHCl$ and $35mL$ of $0\cdot 1NNaOH$ are mixed. The resulting solution will

• A. be neutral
• B. be basic
• C. turn phenolphthalein solution pink
• D. turn methyl orange red.

Answer 1

Answer: (D)

$20mL$ of $0\cdot 5NHCl=20\times 0\cdot 5$ millieq.
$=10$ milli eq a of $HCl$
$35mL$ of $0\cdot 1NNaOH=35\times 0\cdot 1$ milli eq. $=3\cdot 5$ milli eq $\cdot$ of $NaOH$.
Thus, $3\cdot 5$ milli eq a of $NaOH$ will neutralize
$3\cdot 5$ milli eq $\cdot$ of $HCl(10-3\cdot 5)=6\cdot 5millieq\cdot$ of $HCl$ will be left.
Therefore, solution will be acidic and it will turn methyl orange red.