(a) Compare soaps and detergents on the basis of their composition and cleansing action in hard water.

(b) What happens when ethanol is treated with sodium metal? State the behaviour of ethanol in this reaction.

(c) Draw the structure of cyclohexane.

(d) Name the following compound:

$$\text{CH}_3-\text{CH}_2-\text{OH}$$

(a) Comparison of Soaps and Detergents:

• Composition: Soaps are sodium or potassium salts of long-chain carboxylic acids (fatty acids). Detergents are ammonium or sulphonate salts of long-chain carboxylic acids.
• Cleansing Action in Hard Water: Soaps react with calcium and magnesium ions present in hard water to form an insoluble sticky precipitate called scum, which makes them ineffective. Detergents do not form insoluble precipitates with calcium and magnesium ions, meaning they remain highly effective even in hard water.

(b) Ethanol treated with Sodium Metal:

• Reaction: When ethanol reacts with sodium metal, sodium ethoxide is formed and hydrogen gas is evolved with effervescence.
• Chemical Equation:

$$2\text{CH}_3\text{CH}_2\text{OH} + 2\text{Na} \rightarrow 2\text{CH}_3\text{CH}_2\text{ONa} + \text{H}_2 \uparrow$$

• Behaviour of Ethanol: Ethanol behaves as a weak acid in this reaction because it releases a proton ($\text{H}^+$) to bond with the active metal sodium.

(c) Structure of Cyclohexane ($\text{C}_6\text{H}_{12}$):

Cyclohexane consists of six carbon atoms arranged in a ring, with each carbon atom single-bonded to two other carbon atoms and two hydrogen atoms to satisfy its tetravalency.

(d) Name of the compound:

The compound $\text{CH}_3-\text{CH}_2-\text{OH}$ is Ethanol.