Which among the following represents the reaction of formation of the product?

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:

Consider the following data:
Heat of combustion of $H_{2(g)} = -241.8 \ kJ \ mol^{-1}$
Heat of combustion of $C_{(s)} = -393.5 \ kJ \ mol^{-1}$
Heat of combustion of $C_2H_5OH_{(l)} = -1234.7 \ kJ \ mol^{-1}$
The heat of formation of $C_2H_5OH_{(l)}$ is $(-)$ $...... \ kJ \ mol^{-1}$ (Nearest integer).

What is the enthalpy change for the reaction $2C(\text{graphite}) + 3H_{2(g)} \rightarrow C_2H_{6(g)}$ called?

The enthalpy of atomization of $PH_3(g)$ is $228 \, kcal \, mol^{-1}$ and that of $P_2H_4(g)$ is $355 \, kcal \, mol^{-1}$. The $P-P$ bond energy (in $kcal \, mol^{-1}$) is:

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 ...... .