$ Minerals such as carbonates and phosphates acts as buffers.
! Biomolecules contain only 25 elements out of the 109 known elements.

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

To solve the question, we need to analyze the two statements provided:

1. **Assertion**: Minerals such as carbonates and phosphates act as buffers.
2. **Reason**: Biomolecules contain only 25 elements out of the 109 known elements.

### Step-by-Step Solution:

**Step 1: Analyze the Assertion**
- The assertion states that minerals such as carbonates and phosphates act as buffers.
- Buffers are substances that help maintain a stable pH in a solution by neutralizing acids and bases.
- Carbonates (like bicarbonate) and phosphates can absorb excess hydrogen ions (H+) or hydroxide ions (OH-), thus helping to stabilize the pH in biological systems.
- Therefore, the assertion is **correct**.

**Step 2: Analyze the Reason**
- The reason states that biomolecules contain only 25 elements out of the 109 known elements.
- It is true that biological molecules (like proteins, nucleic acids, carbohydrates, and lipids) are primarily composed of a limited number of elements, mainly carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.
- This statement is also **correct**.

**Step 3: Determine the Relationship Between Assertion and Reason**
- Now we need to evaluate whether the reason provided is a correct explanation of the assertion.
- While both statements are true, the reason does not explain why carbonates and phosphates act as buffers. The reason discusses the composition of biomolecules, which is unrelated to the buffering action of carbonates and phosphates.
- Therefore, the reason is **not the correct explanation** of the assertion.

**Step 4: Choose the Correct Option**
- Based on the analysis:
- Both the assertion and reason are correct.
- However, the reason does not explain the assertion.
- Thus, the correct answer is **Option B**: Both assertion and reason are correct, but the reason is not the correct explanation of the assertion.

### Final Answer:
The correct answer is Option B.

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