Which of the following is an endothermic reaction?

$S + \frac{3}{2} O_2 \to SO_3 + 2x \ kcal$
$SO_2 + \frac{1}{2} O_2 \to SO_3 + y \ kcal$
Find out the heat of formation of $SO_2$.

For the allotropic change represented by the equation $C(\text{diamond}) \to C(\text{graphite})$,the enthalpy change is $\Delta H = -1.89 \ kJ$. If $6 \ g$ of diamond and $6 \ g$ of graphite are separately burnt to yield carbon dioxide,the heat liberated in the first case is:

Calculate the enthalpy change of vaporisation of benzene if $13 \ g$ of benzene vaporised by supplying $5.1 \ kJ$ of heat.

Calculate the enthalpy change for the following reaction, using the given bond energies $(\text{kJ/mol})$: $C-H = 414$, $H-O = 463$, $H-Cl = 431$, $C-Cl = 326$, and $C-O = 335$.
$CH_3OH(g) + HCl(g) \rightarrow CH_3Cl(g) + H_2O(g)$

When equal volumes of $1 \ M \ HCl$ and $1 \ M \ H_2SO_4$ are separately neutralized by an excess volume of $1 \ M \ NaOH$ solution,$x \ J$ and $y \ J$ of heat are liberated,respectively. The value of $y / x$ is . . . .