Assertion A: For an ideal solution formed by mixing liquids P and Q, $\Delta_{mix}H = 0$ and $\Delta_{mix}V = 0$

Reason R: No interactions occur between P and Q

In the light of the above statements, choose the most appropriate answer from the options given below.

Question

Assertion A: For an ideal solution formed by mixing liquids P and Q, $\Delta_{mix}H = 0$ and $\Delta_{mix}V = 0$

Reason R: No interactions occur between P and Q

In the light of the above statements, choose the most appropriate answer from the options given below.

Accepted Answer

D. 1. Recall that for an **ideal solution**, mixing two liquids does not change the enthalpy or volume of the system:
$$
\Delta_{mix}H = 0 \quad 	ext{and} \quad \Delta_{mix}V = 0
$$
This matches exactly what **Assertion A** states, so **A is correct**.

2. Now check the reasoning given in **Reason R**, which claims that no interactions occur between P and Q at all.

In reality, an ideal solution does have P–Q interactions; the key condition is that the energy required to break the P–P and Q–Q interactions is exactly equal to the energy released when new P–Q interactions form.

Since the interactions are equal in strength (not absent), $\Delta_{mix}H$ comes out to be zero — not because there are no interactions.

3. Because R gives a false reason (interactions do exist; they are just balanced), **R is incorrect**.

4. Since A is true and R is false, the correct choice is that **A is correct but R is not correct**.

Hence, the answer is **option D**.

Assertion A: For an ideal solution formed by mixing liquids P and Q, ΔmixH=0\Delta_{mix}H = 0Δmix​H=0 and ΔmixV=0\Delta_{mix}V = 0Δmix​V=0 Reason R: No interactions occur between P and Q In the light of the above statements, choose the most appropriate answer from the options given below.

Assertion A: For an ideal solution formed by mixing liquids P and Q, $\Delta_{mix}H = 0$ and $\Delta_{mix}V = 0$

Reason R: No interactions occur between P and Q

In the light of the above statements, choose the most appropriate answer from the options given below.