Answer:

Explanation:
Given:
volume of air in the room, 
temperature of the room, 
<u>Saturation water vapor pressure at any temperature T K is given as:</u>
<u />
<u />
putting T=298 K we have

<u>The no. of moles of water molecules that this volume of air can hold is:</u>
Using Ideal gas law,



is the maximum capacity of the given volume of air to hold the moisture.
Currently we have 80% of n, so the mass of 20% of n:

where;
M= molecular mass of water

is the mass of water that can vaporize further.
Answer:
a) and c).
Explanation:
For a complete destructive interference occur, it must be met the following condition relating the wavelength, and the difference in the paths taken by the sound emitted by the sources until arriving to the listening point:
d = |dA- dB| = (2n-1)*(λ/2)
For n= 1, d = λ/2 = 0.25 m, it doesn't meet any of the cases.
For n=2, d= 3*(λ/2) = 0.75 m
In the case a) we have dA = 2.15 m and dB = 3.00 m, so dB-dA = 0.75 m, which means that in the location stated by case a) a complete destructive interference would occur.
For n=3, d= 5*(λ/2) = 5*0.25 m = 1.25 m.
This is just the case c) because we have dA = 3.75 m and dB = 2.50 m, so dA-dB = 1.25 m, which means that in the location stated by case c) a complete destructive interference would occur also.
The remaining cases don't meet the condition stated above, so the statements found to be true are a) and c),
There is a ner force of 15 N allowing Levi and Clara to mobe the box.