Which among the following are unsaturated hydrocarbons?
$(i) H_3C - CH_2 - CH_2 - CH_3$
$(ii) H_3C - C \equiv C - CH_3$
$(iii) H_3C - CH(CH_3) - CH_3$
$(iv) H_3C - C(CH_3) = CH_2$

On dropping a small piece of sodium in a test tube containing carbon compound $X$ with molecular formula $C_{2}H_{6}O$,a brisk effervescence is observed and a gas $Y$ is produced. On bringing a burning splinter at the mouth of the test tube,the gas evolved burns with a pop sound. Identify $X$ and $Y$. Also,write the chemical equation for the reaction. Write the name and structure of the product formed when you heat $X$ with excess concentrated sulphuric acid.

Which substance is obtained by the reduction of methanal?

What is the compound having $(-CHO)$ functional group called?

What is prepared by the Fischer-Tropsch method?

Which compound contains the $-COOH$ functional group?