Assertion : For the reaction : `N_(2(g))+3H_(2(g))hArr2NH_(3(g)),K_(p)=K_(c)`
Reason : Concentration of gaseous reactants and products is taken as unity.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Reaction:**
The reaction given is:
\[ N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \]

2. **Calculating ΔN (Change in Moles of Gases):**
To find the change in the number of moles of gases (ΔN), we use the formula:
\[ \Delta N = \text{(moles of gaseous products)} - \text{(moles of gaseous reactants)} \]
Here, we have:
- Moles of gaseous products = 2 (from 2NH3)
- Moles of gaseous reactants = 1 (from N2) + 3 (from 3H2) = 4

Therefore,
\[ \Delta N = 2 - 4 = -2 \]

3. **Relating Kp and Kc:**
The relationship between Kp and Kc is given by the equation:
\[ K_p = K_c \cdot R^{\Delta N} \]
Substituting ΔN into the equation:
\[ K_p = K_c \cdot R^{-2} = \frac{K_c}{R^2} \]

4. **Evaluating the Assertion:**
The assertion states that \( K_p = K_c \). From our calculation, we found that:
\[ K_p = \frac{K_c}{R^2} \]
This indicates that \( K_p \) is not equal to \( K_c \) unless \( R^2 = 1 \), which is not the case. Therefore, the assertion is **false**.

5. **Evaluating the Reason:**
The reason states that the concentration of gaseous reactants and products is taken as unity. This statement is misleading in the context of this reaction. The concentrations of gases do not automatically equal unity; they depend on the conditions of the reaction. The only time concentrations are considered unity is for pure solids and liquids in equilibrium expressions. Therefore, the reason is also **false**.

6. **Conclusion:**
Since both the assertion and the reason are false, the correct answer is option 4: Both the assertion and reason are false.