A : Magnesium and Cesium gives blue colour in flame colouration.
R : Mg and Cs are of comparable size.

Options

A. If both Assertion & Reason are true and the reason is the correct explanantion of the assertion, then mark (1).
B. If both Assertion & Reason are true and the reason is the correct explanantion of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false. Them mark (3).
D. If both Assertion and reason are false statement, then mark (4).

Answer

To analyze the given statements, we will break down the assertion (A) and reason (R) step by step.

### Step 1: Understand the Assertion (A)
The assertion states that "Magnesium and Cesium gives blue colour in flame coloration."

**Analysis:**
- Magnesium (Mg) is an alkaline earth metal from Group 2 of the periodic table.
- Cesium (Cs) is an alkali metal from Group 1 of the periodic table.
- When metals are heated in a flame, they can emit characteristic colors due to the excitation of their electrons.
- Cesium is known to produce a blue flame when burned, but magnesium typically does not produce a colored flame; it burns with a bright white light.

**Conclusion for A:** The assertion is **false** because magnesium does not give a blue color in flame coloration.

### Step 2: Understand the Reason (R)
The reason states that "Mg and Cs are of comparable size."

**Analysis:**
- Magnesium has an atomic radius of about 160 pm, while cesium has a much larger atomic radius of about 262 pm.
- Therefore, they are not comparable in size; cesium is significantly larger than magnesium.

**Conclusion for R:** The reason is **false** because magnesium and cesium are not of comparable size.

### Step 3: Evaluate the Relationship between A and R
- Since both the assertion (A) and the reason (R) are false, we conclude that the correct option is that both statements are false.

### Final Answer:
Both the assertion and reason are false.

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