I would say the answer is D
A hygrometer is an instrument used to measure relative humidity. ... To determine the relative humidity, the temperatures are taken from the dry-bulb thermometer and the temperature difference between the wet and dry bulb thermometers.
hygrometer is a weather instrument used to measure the amount of humidity in the atmosphere. There are two main types of hygrometers -- a dry and wet bulb psychrometer and a mechanical hygrometer.
Complete Question
The complete question is shown on the first uploaded image
Answer:
The value of n is 
Explanation:
From the question we are told that
The value of m = 2
For every value of 
The modified version of Balmer's formula is ![\frac{1}{\lambda} = R [\frac{1}{m^2} - \frac{1}{n^2} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Clambda%7D%20%20%3D%20R%20%5B%5Cfrac%7B1%7D%7Bm%5E2%7D%20-%20%5Cfrac%7B1%7D%7Bn%5E2%7D%20%20%5D)
The Rydberg constant has a value of 
The objective of this solution is to obtain the value of n for which the wavelength of the Balmer series line is smaller than 400nm
For m = 2 and n =3
The wavelength is
![\frac{1}{\lambda } = (1.097 * 10^7)[\frac{1}{2^2} - \frac{1}{3^2} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Clambda%20%7D%20%3D%20%281.097%20%2A%2010%5E7%29%5B%5Cfrac%7B1%7D%7B2%5E2%7D%20-%20%5Cfrac%7B1%7D%7B3%5E2%7D%20%20%5D)


For m = 2 and n = 4
The wavelength is
![\frac{1}{\lambda } = (1.097 * 10^7)[\frac{1}{2^2} - \frac{1}{4^2} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Clambda%20%7D%20%3D%20%281.097%20%2A%2010%5E7%29%5B%5Cfrac%7B1%7D%7B2%5E2%7D%20-%20%5Cfrac%7B1%7D%7B4%5E2%7D%20%20%5D)


For m = 2 and n = 5
The wavelength is
![\frac{1}{\lambda } = (1.097 * 10^7)[\frac{1}{2^2} - \frac{1}{5^2} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Clambda%20%7D%20%3D%20%281.097%20%2A%2010%5E7%29%5B%5Cfrac%7B1%7D%7B2%5E2%7D%20-%20%5Cfrac%7B1%7D%7B5%5E2%7D%20%20%5D)


For m = 2 and n = 6
The wavelength is
![\frac{1}{\lambda } = (1.097 * 10^7)[\frac{1}{2^2} - \frac{1}{6^2} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Clambda%20%7D%20%3D%20%281.097%20%2A%2010%5E7%29%5B%5Cfrac%7B1%7D%7B2%5E2%7D%20-%20%5Cfrac%7B1%7D%7B6%5E2%7D%20%20%5D)


For m = 2 and n = 7
The wavelength is
![\frac{1}{\lambda } = (1.097 * 10^7)[\frac{1}{2^2} - \frac{1}{7^2} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Clambda%20%7D%20%3D%20%281.097%20%2A%2010%5E7%29%5B%5Cfrac%7B1%7D%7B2%5E2%7D%20-%20%5Cfrac%7B1%7D%7B7%5E2%7D%20%20%5D)


So the value of n is 7
This would be gas, due to it not essentially having a definite volume.
The answer is 1000/20. Or that’s what I’m guessing. Lol
Answer:
the awnser is A becuse the hair help.