Which of the following statements are correct?

Options

A. (a)Changes inair temperature have no effect on the speed of sound.
B. (b)Changes in air pressure have no effect on the speed of sound.
C. (c)The speed of sound in water is higher that in air.
D. (d)The speed of sound in water is lower than in air.

Explanation

To determine which statements about the speed of sound are correct, let's analyze each option step by step.

### Step 1: Analyze Statement A
**Statement A:** Changes in air temperature have no effect on the speed of sound.

- The speed of sound in air is affected by temperature. The relationship can be expressed as:
\[ v \propto \sqrt{T} \]
where \( v \) is the speed of sound and \( T \) is the temperature in Kelvin. This means that as temperature increases, the speed of sound also increases.

**Conclusion:** Statement A is **incorrect**.

### Step 2: Analyze Statement B
**Statement B:** Changes in air pressure have no effect on the speed of sound.

- The speed of sound is primarily influenced by the medium's temperature and density. The formula for the speed of sound can be expressed as:
\[ v = \sqrt{\frac{Y}{\rho}} \]
where \( Y \) is the Young's modulus and \( \rho \) is the density of the medium. At constant temperature, changes in pressure do not affect the speed of sound because the density and pressure change proportionally, leaving the speed of sound unchanged.

**Conclusion:** Statement B is **correct**.

### Step 3: Analyze Statement C
**Statement C:** Speed of sound in water is higher than in air.

- The speed of sound is indeed higher in water than in air. This is due to the higher bulk modulus of water compared to air, which means that sound travels faster in denser media. The relationship can be summarized as:
\[ v \propto \sqrt{B} \]
where \( B \) is the bulk modulus. Since water has a higher bulk modulus than air, the speed of sound in water is greater.

**Conclusion:** Statement C is **correct**.

### Step 4: Analyze Statement D
**Statement D:** Speed of sound in water is lower than in air.

- This statement contradicts the findings from Statement C. Since we established that the speed of sound in water is higher than in air, this statement is false.

**Conclusion:** Statement D is **incorrect**.

### Final Summary
The correct statements are:
- **B:** Changes in air pressure have no effect on the speed of sound. (Correct)
- **C:** Speed of sound in water is higher than in air. (Correct)