What is the number of moles of solute dissolved in $1 \ L$ of solution called?

Which of the following substances will not give carbon dioxide on treatment with dilute acid?

Equal lengths of magnesium ribbon are taken in two test tubes $A$ and $B$. $H_{2}SO_{4}$ is added to test tube $A$ and $H_{2}CO_{3}$ is added to test tube $B$ in equal amounts.
$(a)$ Write chemical equations for both the reactions.
$(b)$ Out of the two acids taken above,which one will have a lower $pH$ value and lower $H^{+}$ concentration,respectively?

What is the molecular mass of $NaOH$?

Three beakers labelled as $A$,$B$ and $C$ each containing $25 \, mL$ of water were taken. $A$ small amount of $NaOH$,anhydrous $CuSO_4$ and $NaCl$ were added to the beakers $A$,$B$ and $C$ respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers $A$ and $B$,whereas in case of beaker $C$,the temperature of the solution falls. Which one of the following statement$(s)$ is(are) correct?
$(i)$ In beakers $A$ and $B$,exothermic process has occurred.
$(ii)$ In beakers $A$ and $B$,endothermic process has occurred.
$(iii)$ In beaker $C$ exothermic process has occurred.
$(iv)$ In beaker $C$ endothermic process has occurred.

Write balanced chemical equations for the following:
$(a)$ Calcium carbonate reacts with hydrochloric acid.
$(b)$ Calcium oxychloride reacts with hydrochloric acid.
$(c)$ Sodium hydroxide reacts with zinc.