If $(i)$ $C + O_2 \to CO_2$,$(ii)$ $C + 1/2 O_2 \to CO$,$(iii)$ $CO + 1/2 O_2 \to CO_2$,the heats of reaction are $Q$,$-12$,and $-10$ respectively. Then $Q =$ ?

Fill in the blanks:
$(i)$ The enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states is called the ...... of that compound.
$(ii)$ The total heat change in a chemical reaction is equal to the algebraic sum of the heat changes of the individual steps of the reaction. This law was given by ............. .
$(iii)$ $A$ process during which there is no exchange of heat between the system and the surroundings is called an ................ process.
$(iv)$ The standard enthalpy value of any element in its standard state is considered to be ...... .

The heat of neutralisation of one equivalent of an acid by one equivalent of a base is minimum when:

Consider the reaction $4NO_2(g) + O_2(g) \rightarrow 2N_2O_5(g)$, $\Delta_rH = -111 \ kJ$. If $N_2O_5(s)$ is formed instead of $N_2O_5(g)$, what will be the value of $\Delta_rH$ in $kJ$? (Given: $\Delta H_{sub} = 54 \ kJ \ mol^{-1}$ for $N_2O_5$)

Carbon and carbon monoxide burn in oxygen to form carbon dioxide according to the following reactions:
$C(s) + O_2(g) \to CO_2(g)$; $\Delta H = -394 \ kJ \ mol^{-1}$
$2CO(g) + O_2(g) \to 2CO_2(g)$; $\Delta H = -569 \ kJ \ mol^{-1}$
The heat of formation of $1 \ mol$ of carbon monoxide is thus ..... $kJ \ mol^{-1}$.

For the reaction $OF_{2(g)} \to O_{(g)} + 2F_{(g)}$,$\Delta_{rxn}H$ is $368 \ kJ$. What is the average $O-F$ bond energy in $kJ/mol$?