The reaction of compound E (CH3CH=CH2, propene) with Br2/CCl4 is an electrophilic addition reaction.

The product is 1,2-dibromopropane.

6 (a)

i)

Given percentages: C = 35.0%, H = 6.6%, Br = 58.4%.
R.A.M: C = 12, H = 1, Br = 79.9.

Moles of C $= \frac{35.0 \text{ g}}{12 \text{ g/mol}} = 2.9167 \text{ mol}$
Moles of H $= \frac{6.6 \text{ g}}{1 \text{ g/mol}} = 6.6 \text{ mol}$
Moles of Br $= \frac{58.4 \text{ g}}{79.9 \text{ g/mol}} = 0.7309 \text{ mol}$

Smallest number of moles is 0.7309 (for Br).

Ratio of C $= \frac{2.9167}{0.7309} \approx 3.99 \approx 4$
Ratio of H $= \frac{6.6}{0.7309} \approx 9.03 \approx 9$
Ratio of Br $= \frac{0.7309}{0.7309} = 1$

The empirical formula is $\boxed{\text{C}_4\text{H}_9\text{Br}}$.

ii)

Empirical formula mass of $\text{C}_4\text{H}_9\text{Br} = (4 \times 12) + (9 \times 1) + (1 \times 79.9) = 48 + 9 + 79.9 = 136.9 \text{ g/mol}$.

Given molecular weight = 136.9.
Since the empirical formula mass (136.9) is equal to the molecular weight (136.9), the molecular formula is the same as the empirical formula.

The molecular formula is $\boxed{\text{C}_4\text{H}_9\text{Br}}$.

6 (b)

i)
To distinguish between $\text{CH}_3\text{CH}_2\text{CHO}$ (propanal, an aldehyde) and $\text{CH}_3\text{COCH}_3$ (propanone, a ketone):
Use Tollens' reagent.

• Propanal (aldehyde) will react with Tollens' reagent (ammoniacal silver nitrate) upon warming to form a silver mirror on the inside of the test tube.
• Propanone (ketone) will show no reaction.

ii)
To distinguish between $\text{CH}_3\text{CH}_2\text{C}\equiv\text{CH}$ (but-1-yne, a terminal alkyne) and $\text{CH}_3\text{C}\equiv\text{CCH}_3$ (but-2-yne, an internal alkyne):
Use ammoniacal silver nitrate solution.

• But-1-yne (terminal alkyne) will react to form a white precipitate of silver acetylide.
• But-2-yne (internal alkyne) will show no reaction.

6 (c)
Organic chemistry is the branch of chemistry that studies the structure, properties, composition, reactions, and preparation of carbon-containing compounds.
Two unique properties of carbon:

1. Catenation: Carbon atoms can form strong covalent bonds with other carbon atoms, leading to the formation of long chains, branched chains, and rings.
2. Tetravalency: Carbon atoms can form four covalent bonds, allowing for a vast diversity of stable molecular structures.

6 (d)

i)
A functional group is a specific group of atoms within a molecule that is responsible for the characteristic chemical reactions of that molecule.

ii)
The systematic name of the compound $\text{CH}_3\text{CH}(\text{CH}_3)\text{CONH}_2$ is 2-Methylpropanamide.

iii)
The compound $\text{CH}_3\text{CH}(\text{CH}_3)\text{CONH}_2$ exhibits optical isomerism because it contains a chiral carbon atom (the carbon bonded to the methyl group, hydrogen, and the amide group).

6 (e)

i)
The asymmetric carbon atom in $\text{CH}_3\text{CH}(\text{NH}_2)\text{COOH}$ is the central