*Question T3B11:
What is the approximate velocity of a radio wave in free space?*  

*Correct Answer is  B: 300,000,000 meters per second*  

### AI Response: (may contain errors)  

The correct answer to the question about the approximate velocity of a radio wave in free space is:

**B: 300,000,000 meters per second**

### Explanation:

1. **Why the correct answer is correct:**
   - The speed of light in a vacuum, which is the same as the speed of radio waves, is approximately $299,792,458$ meters per second. For practical purposes, this is often rounded to $300,000,000$ meters per second. This speed is a fundamental constant in physics, denoted as $c$.

2. **Why the other choices are incorrect:**
   - **A: 150,000 meters per second**  
     This value is significantly lower than the actual speed of light. It does not reflect the speed of any electromagnetic wave in free space.
   
   - **C: 300,000,000 miles per hour**  
     While this number is close to the speed of light, it is not in the correct units for this question. The speed of light is typically expressed in meters per second in scientific contexts.
   
   - **D: 150,000 miles per hour**  
     This is also much lower than the actual speed of light. To convert miles per hour to meters per second, you would use the conversion factor:  
     $$1 \text{ mile per hour} \approx 0.44704 \text{ meters per second}$$  
     Thus, $150,000$ miles per hour is approximately $67,056$ meters per second, which is still far from the speed of light.

### Useful Formulas:
- The speed of light in a vacuum is a fundamental constant:
  $$c \approx 300,000,000 \text{ m/s}$$

This knowledge is essential for understanding radio wave propagation and the behavior of electromagnetic waves in various media.