The catenation tendency of C, Si and Ge is in the order $Ge<Si<C.$ The bond energies $\left(\mathrm{i}\mathrm{n} kJ mo{l}^{-1} \right)$ of $C-C, Si-Si$ and $Ge-Ge$ bonds, respectively are

Identify the correct order of boiling points of the following compounds 

(A) ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{OH}$

(B) ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{CHO}$

(C) ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{COOH}$

When water gas is mixed with half its volume of hydrogen and the mixture is compressed 300 atmospheric pressure and passed over $\mathrm{ZnO}.{\mathrm{Cr}}_2{\mathrm{O}}_3$ catalyst a colourless liquid is obtained which is used as a solvent for paint and varnishes. The liquid will be 

Which of the following structures contain $sp$-hybridised carbon atom(s)?

I. $\mathrm{HC}\equiv \mathrm{CH}$

II. ${\mathrm{H}}_2\mathrm{C}=\mathrm{C}={\mathrm{CH}}_2$

III. 

IV. 

How many pi bonds and sigma bonds are present in following molecule?