Calculate enthalpy change for following reaction.

$$\mathrm{H}_2 \mathrm{C}=\mathrm{CH}_{2(\mathrm{~g})}+\mathrm{H}_{2(\mathrm{~g})} \longrightarrow \mathrm{H}_3 \mathrm{C}-\mathrm{CH}_{3(\mathrm{~g})}$$

[The bond energy of $\mathrm{C}-\mathrm{H}, \mathrm{C}-\mathrm{C}, \mathrm{C}=\mathrm{C}$ and $\mathrm{H}-\mathrm{H}$ is $414,347,615$ and 435 kJ respectively]

Identify the product 'B' in the following reaction.

Ethylphenyl ketone $\xrightarrow{\mathrm{H}_2 \mathrm{~N}-\mathrm{NH}_2}$ A $\xrightarrow[\Delta]{\mathrm{KOH}, \mathrm{HO}\left(\mathrm{CH}_2\right)_2 \mathrm{OH}}$ B

Which from following is NOT a lanthonoid element?

For the reaction, $A+3 B \longrightarrow 2 C$

rate of consumption of A is $1.4 \mathrm{~mol} \mathrm{~dm}^{-3} \mathrm{~sec}^{-1}$. Calculate rate of formation of C ?