ANS:C - either (a) or (b)

When it is stated that the rate of a chemical reaction is not much affected if the reactants are in either (a) solids or (b) liquids, it means that the reaction rate is relatively slower compared to reactions involving gaseous reactants, but it is not significantly hindered as it would be in the case of solid reactants. Let's break down both scenarios: (a) Solids:

• When reactants are in solid form, the rate of reaction can be slower compared to when they are in liquid or gaseous form.
• Solid reactants typically have limited surface area and mobility, making it challenging for reactant particles to come into contact and react with each other.
• However, some solid-solid reactions can still proceed at a reasonable rate, especially if the solid particles have a high surface area or if the reaction occurs at elevated temperatures.

(b) Liquids:

• When reactants are in liquid form, the rate of reaction is typically faster compared to solid reactants but slower than gaseous reactants.
• Liquid reactants have more mobility compared to solids, allowing them to mix and come into contact more easily.
• However, liquid reactants may still have limitations in terms of collision frequency and orientation compared to gaseous reactants, leading to a slower reaction rate.

Therefore, when it is stated that the rate of reaction is not much affected if the reactants are in either solids or liquids, it means that while the reaction rate may be slower compared to reactions involving gaseous reactants, it is not significantly hindered as it would be in the case of solid reactants. Both solids and liquids allow for some degree of reactant mobility and contact, enabling the reaction to proceed at a reasonable rate under appropriate conditions.