The answer is:
71.6 <span>°F</span>
Answer:
Ozone is a gas in the atmosphere that protects everything living on the Earth from harmful ultraviolet (UV) rays from the Sun. Without the layer of ozone in the atmosphere, it would be very difficult for anything to survive on the surface.
Explanation:
Ozone layer, also called ozonosphere, region of the upper atmosphere, between roughly 15 and 35 km (9 and 22 miles) above Earth’s surface, containing relatively high concentrations of ozone molecules (O3). Approximately 90 percent of the atmosphere’s ozone occurs in the stratosphere, the region extending from 10–18 km (6–11 miles) to approximately 50 km.
Explanation:
Formula which holds true for a leans with radii 
and 
and index refraction n is given as follows.
![\frac{1}{f} = (n - 1) [\frac{1}{R_{1}} - \frac{1}{R_{2}}]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf%7D%20%3D%20%28n%20-%201%29%20%5B%5Cfrac%7B1%7D%7BR_%7B1%7D%7D%20-%20%5Cfrac%7B1%7D%7BR_%7B2%7D%7D%5D)
Since, the lens is immersed in liquid with index of refraction 
. Therefore, focal length obeys the following.
![\frac{1}{f_{1}} = \frac{n - n_{1}}{n_{1}} [\frac{1}{R_{1}} - \frac{1}{R_{2}}]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf_%7B1%7D%7D%20%3D%20%5Cfrac%7Bn%20-%20n_%7B1%7D%7D%7Bn_%7B1%7D%7D%20%5B%5Cfrac%7B1%7D%7BR_%7B1%7D%7D%20-%20%5Cfrac%7B1%7D%7BR_%7B2%7D%7D%5D)
![\frac{1}{f(n - 1)} = [\frac{1}{R_{1}} - \frac{1}{R_{2}}]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf%28n%20-%201%29%7D%20%3D%20%5B%5Cfrac%7B1%7D%7BR_%7B1%7D%7D%20-%20%5Cfrac%7B1%7D%7BR_%7B2%7D%7D%5D)
and, 
or, 
= 32.4 cm
Using thin lens equation, we will find the focal length as follows.
Hence, image distance can be calculated as follows.
= 47.9 cm
Therefore, we can conclude that the focal length of the lens in water is 47.9 cm.
Clever problem.
We know that the beat frequency is the DIFFERENCE between the frequencies of the two tuning forks. So if Fork-A is 256 Hz and the beat is 6 Hz, then Fork-B has to be EITHER 250 Hz OR 262 Hz. But which one is it ?
Well, loading Fork-B with wax increases its mass and makes it vibrate SLOWER, and when that happens, the beat drops to 5 Hz. That means that when Fork-B slowed down, its frequency got CLOSER to the frequency of Fork-A ... their DIFFERENCE dropped from 6 Hz to 5 Hz.
If slowing down Fork-B pushed it CLOSER to the frequency of Fork-A, then its natural frequency must be ABOVE Fork-A.
The natural frequency of Fork-B, after it gets cleaned up and returns to its normal condition, is 262 Hz. While it was loaded with wax, it was 261 Hz.
