Soaps are biodegradable because their hydrocarbon chains are: MCQ with Answer and Explanation

Explanation:
Hydrogen has a higher calorific value than CNG, making it a better fuel in terms of energy output per unit mass. However, R states it is explosive and hard to store, which is a disadvantage, not the reason it is a better fuel. Thus, both are true, but R does not explain A.

Explanation:
C₂H₄ (ethene) is an alkene with a carbon-carbon double bond, thus unsaturated. The general formula CnH₂n indicates an alkene or cycloalkane. C₃H₈, C₄H₁₀, C₅H₁₂ follow CnH₂n+2 and are saturated alkanes. Unsaturated compounds undergo addition reactions, whereas saturated undergo substitution.

Explanation:
The reactivity of metals with water depends on their position in the reactivity series. Sodium and potassium are highly reactive alkali metals that react vigorously and exothermically with cold water to form hydroxides and hydrogen gas. Iron reacts only with steam, while copper and silver do not react with water.