(a) The letters R,S,T represent an alkene, an alkene and a terminal alkyne respectively. Which of R, S and T typically undergo(es) the following reactions? ...

(a)

Taking R as an alkane, S as an alkene and T as a terminal alkyne:

1. Addition reaction: S and T.
2. Combustion: R, S and T.
3. Substitution reaction: R and T.

(b)

1. The process is dehydration of the alkanol.
2. The third member is propan-1-ol.
   Structural formula: CH₃CH₂CH₂OH.
3. A primary alkanol is oxidised to the corresponding alkanoic acid by excess acidified potassium manganate(VII) solution.
   For example:
   \[\mathrm{CH_3CH_2OH + 2[O] \rightarrow CH_3COOH + H_2O}\]

(c)

1. Add aqueous sodium hydrogencarbonate or sodium carbonate to the acid. Brisk effervescence of carbon dioxide is produced.
   \[\mathrm{RCOOH + NaHCO_3 \rightarrow RCOONa + CO_2 + H_2O}\]
2. \[\mathrm{HCOOH + CH_3CH_2OH \xrightleftharpoons[\ ]{conc.\ H_2SO_4} HCOOCH_2CH_3 + H_2O}\]

   The ester formed is ethyl methanoate.

3. The mineral acid acts as a catalyst in the esterification reaction.

(d)

1. H is carbon dioxide, CO₂.
2. Starch is a polysaccharide. The diastase (amylase) enzyme in malt hydrolyses starch to maltose, a reducing sugar.
   \[\mathrm{(C_6H_{10}O_5)_n + \tfrac{n}{2}H_2O \xrightarrow[55^{\circ}C]{diastase} \tfrac{n}{2}C_{12}H_{22}O_{11}}}\]

   Yeast subsequently ferments the sugar to ethanol, J, and carbon dioxide:

   \[\mathrm{C_6H_{12}O_6 \xrightarrow{yeast} 2C_2H_5OH + 2CO_2}\]
3. J is ethanol. A sample is obtained from the fermented mixture by simple distillation.

Distillation set-up for obtaining ethanol (J)

The fermented mixture is heated gently in a water bath. Ethanol distils over, condenses in the Liebig condenser and is collected as the distillate.