Introduction To Pollution Types

Ultrasound of how much frequency is beamed into a human body for sonography?

1. 30-40 MHz

2. 15-30 MHz

3. 1-15 MHz

4. 45-70 MHz

Which of the following is a secondary pollutant?

$1.$ $\mathrm{CO}$

$2.$ ${\mathrm{CO}}_2$

$3.$ ${\mathrm{SO}}_2$

$4.$ ${\mathrm{O}}_3$