Which of the following is/are ne applications of Ultrasonic Waves ?
(i) For measuring the depth of Sea (ii) In sterilizing of a liquid (iii) In Ultrasonography (iv) In sterilizing a needle.

Options

A. (i), (ii) and (iii)
B. Only (iv)
C. Both (iii) and (iv)
D. Only (ii)

Explanation

To determine the applications of ultrasonic waves from the given options, we can analyze each statement one by one.

1. **For measuring the depth of Sea**:
- Ultrasonic waves are indeed used in sonar technology to measure the depth of the sea. This is done by sending ultrasonic waves from a ship to the seabed and measuring the time it takes for the waves to return. Therefore, this application is correct.

2. **In sterilizing of a liquid**:
- Ultrasonic waves can be used in the process of sterilization. They create cavitation bubbles in the liquid that can help in cleaning and sterilizing. Thus, this application is also correct.

3. **In Ultrasonography**:
- Ultrasonography is a medical imaging technique that uses ultrasonic waves to visualize internal organs. This application is widely used in hospitals for various diagnostic purposes. Therefore, this application is correct as well.

4. **In sterilizing a needle**:
- While ultrasonic waves can be used for cleaning instruments, the specific application of sterilizing a needle is not typically highlighted as a primary use of ultrasonic waves. Sterilization usually involves other methods like autoclaving or chemical sterilization. Therefore, this application is not considered correct.

Now, summarizing the findings:
- Applications of ultrasonic waves include:
- (i) For measuring the depth of Sea - **Correct**
- (ii) In sterilizing of a liquid - **Correct**
- (iii) In Ultrasonography - **Correct**
- (iv) In sterilizing a needle - **Not Correct**

Thus, the correct applications of ultrasonic waves from the options given are (i), (ii), and (iii).

### Final Answer:
The correct applications of ultrasonic waves are (i), (ii), and (iii).

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