What is the weight of $H_2SO_4$ (in $g$) required to completely dissolve $3 \ g$ of magnesium carbonate?

Under the same conditions,how many $mL$ of $1 \ M \ KOH$ and $0.5 \ M \ H_2SO_4$ solution,respectively,when mixed to form a total volume of $100 \ mL$,produce the maximum rise in temperature?

One and a half mole of oxygen combine with aluminium to form $Al_2O_3$. The weight of aluminium metal used in this reaction is .............. $g$ (Atomic weight of $Al = 27$).

In the above reaction,$3.9 \ g$ of benzene on nitration gives $4.92 \ g$ of nitrobenzene. The percentage yield of nitrobenzene in the above reaction is............. $\%$. (Round off to the Nearest Integer).
(Given atomic mass: $C : 12.0 \ u$,$H : 1.0 \ u$,$O : 16.0 \ u$,$N : 14.0 \ u$)

In dilute aqueous $H_2SO_4$,the complex diaquodioxalatoferrate$(II)$ is oxidized by $MnO_4^-$. For this reaction,the ratio of the rate of change of $[H^{+}]$ to the rate of change of $[MnO_4^-]$ is

What products are formed when $1 \ mol$ of magnesium nitride is reacted with excess water?