Which of the following is NOT a rational number?

Correct option is B

Given: We need to identify which of the options is not a rational number.
Concept Used:
A rational number can be expressed as a fraction of two integers, i.e., it can be written in the form of p/q where both p and q are integers, and q is not equal to 0.
The square root of a perfect square is a rational number, while the square root of a non-perfect square is irrational.
Solution:
For √(3² + 4²):
Calculate the value inside the square root:
3² + 4² = 9 + 16 = 25.
So, √25 = 5, which is a rational number.
For √12.96:
The square root of 12.96 is 3.6, which is a rational number because it can be expressed as a fraction (36/10).
For √125:
125 is not a perfect square, so √125 is an irrational number.
For √900:
The square root of 900 is 30, which is a rational number.
Since √125 is not a perfect square, it is an irrational number.
Final Answer: (b) √125