# How much water is needed to dilute 10 ml of 10N hydrochloric acid to make it exactly decinormal (0.1 N)?

$V_1$ = 10 ml
$N_1$ = 10 N
$N_2$ = 0.1 N
Volume of water added (x) = $V_2 – V_1$
$N_1V_1 = N_2V_2$
10 $\times$ 10 = 0.1 $\times V_2$
$V_2$= 1000 ml
Volume of water = 1000 – 10 = 990 ml.
Hence (A) is the correct answer.
answered Jun 6, 2014