For the spontaniety of a reaction , which is true-

Options

A. `DeltaG=+"ve",DeltaH=+"ve"`
B. `DeltaH=+"ve",DeltaS=-"ve"`
C. `DeltaG=+"ve",DeltaH=-"ve"`
D. `DeltaH=-"ve",DeltaS=+"ve"`

Answer

To determine the spontaneity of a reaction, we can use the Gibbs free energy equation:

### Step-by-Step Solution:

1. **Understand the Gibbs Free Energy Equation**:
The equation that relates Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) is given by:
\[ \Delta G = \Delta H - T \Delta S \]
where \( T \) is the temperature in Kelvin.

2. **Identify Conditions for Spontaneity**:
For a reaction to be spontaneous, the change in Gibbs free energy (ΔG) must be negative:
\[ \Delta G < 0 \]

3. **Analyze the Equation**:
From the equation, we can see that:
- If ΔH is negative (exothermic reaction) and ΔS is positive (increase in disorder), then:
\[ \Delta G = \Delta H - T \Delta S < 0 \]
This means that both conditions lead to a negative ΔG, indicating spontaneity.

4. **Evaluate Possible Options**:
According to the problem, we need to find which option states that ΔH is negative and ΔS is positive. The options given are:
- Only the 3rd and 4th options mention ΔH as negative.
- Among these, only the 4th option states ΔS as positive.

5. **Conclusion**:
Therefore, the correct option that satisfies the conditions for spontaneity (ΔH negative and ΔS positive) is option 4.

### Final Answer:
The correct statement for the spontaneity of a reaction is that ΔH is negative and ΔS is positive, making ΔG negative.

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