Question

The amount of water which must be added to a given solution of concentration, $40$ mg silver nitrate per mL to yield a solution of concentration of $16$ mg silver nitrate per mL is :

• A. $1.5$ mL
• B. $2.0$ mL
• C. $2.3$ mL
• D. $2.6$ mL

Answer 1

The correct option is A $1.5$ mL

Let the volume of the diluted solution be $V$ mL.

Initially $1$ mL of solution contains $40$ mg.

After dilution, $40$ mg will be present in $V$ mL whose concentration is $16$ mg silver per mL.

Thus, $V$ mL will contain $16V$ mg.

$16V$ mg $=40$ mg.

$V=2.5$ mL

$\therefore$ The amount of water that must be added $=2.5-1=1.5$ mL.