A: In` CrO_(5)` oxidation state of `Cr` is +10
R: `Cr_(2)O_(7)^(2-)` (aq) is yellow in colour

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

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

### Step-by-Step Solution:

1. **Understanding the Assertion:**
- The assertion states that in CrO₅, the oxidation state of Cr is +10.
- To find the oxidation state of Cr in CrO₅, we can use the formula:
\[ \text{Oxidation state of Cr} + 5 \times (\text{Oxidation state of O}) = 0 \]
- The oxidation state of O is typically -2. Thus, we can write:
\[ x + 5(-2) = 0 \implies x - 10 = 0 \implies x = +10 \]
- Therefore, the assertion that the oxidation state of Cr in CrO₅ is +10 is **true**.

2. **Understanding the Reason:**
- The reason states that Cr₂O₇²⁻ (dichromate ion) is yellow in color.
- However, the dichromate ion (Cr₂O₇²⁻) is known to be orange in color, not yellow. The yellow color is associated with the chromate ion (CrO₄²⁻).
- Therefore, the reason that Cr₂O₇²⁻ is yellow is **false**.

3. **Conclusion:**
- The assertion is true, and the reason is false. Hence, the correct option is that the assertion is true and the reason is false.

### Final Answer:
The correct answer is option 3: Assertion is true, Reason is false.

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