Three beakers labeled as A, B and C each containing $25$ $\text{ml}$ of water were taken. A small amount of $\mathrm{NaOH}$, anhydrous ${\mathrm{CuSO}}_4$ and $\mathrm{NaCl}$ 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 is (are) correct?
$1$. In beakers A and B, the exothermic process has occurred.
$2$. In beakers A and B, the endothermic process has occurred.
$3$. In beaker C, the exothermic process has occurred.
$4$. In beaker C, the endothermic process has occurred.

Which among the following is (are) double displacement reaction(s)?

$\left(\mathrm{i}\right) \mathrm{Pb}+{\mathrm{CuCl}}_2\to {\mathrm{PbCl}}_2+\mathrm{Cu}$

$\left(\mathrm{ii}\right) {\mathrm{Na}}_2{\mathrm{SO}}_4+{\mathrm{BaCl}}_2\to {\mathrm{BaSO}}_4+2\mathrm{NaCl}$

$\left(\mathrm{iiii}\right) \mathrm{C}+{\mathrm{O}}_2\to {\mathrm{CO}}_2$

$\left(\mathrm{iv}\right) {\mathrm{CH}}_4+2{\mathrm{O}}_2\to {\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O}$

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by the liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is are true about slaking of lime and the solution formed?

(i) It is an endothermic reaction.

(ii) It is exothermic reaction.

(iii) The $\mathrm{pH}$ of the resulting solution will be more than seven.

(iv)The $\mathrm{pH}$ of the resulting solution will be less than seven.

Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved?

$\left(\mathrm{i}\right)$ Displacement reaction

$\left(\mathrm{ii}\right)$ Precipitation reaction

$\left(\mathrm{iii}\right)$ Combination reaction

$\left(\mathrm{iv}\right)$ Double displacement reaction

Which of the following is(are) an endothermic process(es)?

(i) Dilution of sulphuric acid

(ii) Sublimation of dry ice

(iii) Condensation of water vapours

(iv) Evaporation of water