What is the normality of $1.5 \ M \ H_3PO_4$ (in $.5$)?

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].

For the reaction,$A \to nB$. At the point of intersection of the two curves in the given graph,the concentration of $B$ is given by:

If $1/2 \text{ mole of oxygen reacts with aluminum to form } Al_2O_3, \text{ the mass of aluminum metal consumed in the reaction is } ..... \text{ g. } (Al=27)$

The minimum amount of $O_2\,(g)$ consumed per gram of reactant is for the reaction: (Given atomic mass: $Fe = 56, O = 16, Mg = 24, P = 31, C = 12, H = 1$)

What quantity of oxygen is required for complete burning of $15.6 \ g$ benzene (in $g$)?