Which of the following is not a proposition?

Options

A. 7 is an odd number
B. `sqrt(2)` is an irrational number
C. Mumbai is the capital of India
D. Mathematics is a difficult subject

Answer

To determine which of the given statements is not a proposition, we need to understand what a proposition is. A proposition is a declarative statement that can be classified as either true or false, but not both.

Let's analyze each option step by step:

1. **Option 1: "7 is an odd number."**
- This statement is true because 7 is indeed an odd number. Since it can be classified as true, this is a proposition.

2. **Option 2: "√2 is an irrational number."**
- This statement is also true. The square root of 2 cannot be expressed as a fraction of two integers, which makes it an irrational number. Therefore, this is a proposition.

3. **Option 3: "Mumbai is the capital of India."**
- This statement is false because the capital of India is New Delhi, not Mumbai. However, it can still be classified as a proposition since it is definitively true or false.

4. **Option 4: "Mathematics is a difficult subject."**
- This statement is subjective. It can be true for some people and false for others, depending on individual experiences and opinions. Since it cannot be definitively classified as true or false, it does not meet the criteria of a proposition.

Based on the analysis, the statement that is not a proposition is:

**Answer: Option 4 - "Mathematics is a difficult subject."**