In the following reaction sequence,the $\%$ yield for reaction $I$ is $60 \%$ and that of reaction $II$ is $50 \%$. The overall yield of the complete reaction is $..........\%$ [nearest integer].

$6.023 \times 10^{22}$ molecules are present in $10 \ g$ of a substance $'x'.$ The molarity of a solution containing $5 \ g$ of substance $'x'$ in $2 \ L$ solution is.......... $\times 10^{-3}$

Commercial concentrated sulfuric acid is $95\% $ $H_2SO_4$ by weight. If the density of this commercial acid is $1.834 \ g \ cm^{-3}$,the molarity of this solution is ....... $M$.

How many millilitres of $6.0 \ M$ hydrochloric acid should be used to prepare $150 \ mL$ of a solution which is $0.30 \ M$ in hydrogen ion?

Galena (an ore) is partially oxidized by passing air through it at high temperature. After some time,the passage of air is stopped,but the heating is continued in a closed furnace such that the contents undergo self-reduction. The weight (in $kg$) of $Pb$ produced per $kg$ of $O_2$ consumed is $. . . . .$ (Atomic weights in $g \ mol^{-1}: O = 16, S = 32, Pb = 207$)

The molarity of $0.2 \ N$ $Na_2CO_3$ solution will be (in $M$)