Answer:
A

B

Explanation:
From the question we are told that
The wavelength is
The angle of first bright fringe is
The order of the fringe considered is n =1
Generally the condition for constructive interference is
=> 
=> 
Converting to cm

Generally the number of grating pre centimeter is mathematically represented as

=> 
=> 
Considering question B
From the question we are told that
The first wavelength is
The second wavelength is
The order of the fringe is 
The grating is 
Generally the slit width is mathematically represented as

=> 
=> 
Generally the condition for constructive interference for the first ray is mathematically represented as
=>
=> ![\theta_1 = sin^{-1} [\frac{ 2 * 650 *10^{-9} }{ 2*10^{-6}}]](https://tex.z-dn.net/?f=%5Ctheta_1%20%3D%20sin%5E%7B-1%7D%20%5B%5Cfrac%7B%202%20%2A%20%20%20650%20%2A10%5E%7B-9%7D%20%7D%7B%202%2A10%5E%7B-6%7D%7D%5D)
=> 
Generally the condition for constructive interference for the second ray is mathematically represented as
=>
=> ![\theta_2 = sin^{-1} [\frac{ 2 * 420 *10^{-9} }{ 2*10^{-6}}]](https://tex.z-dn.net/?f=%5Ctheta_2%20%3D%20sin%5E%7B-1%7D%20%5B%5Cfrac%7B%202%20%2A%20%20%20420%20%2A10%5E%7B-9%7D%20%7D%7B%202%2A10%5E%7B-6%7D%7D%5D)
=> 
Generally the angular separation is mathematically represented as

=> 
=> 
If kl is kiloliters and dl is deciliters, 2019kl=2.019e+7
Answer:
relative density is the density divided by some reference density.
for liquids like mercury the reference density is most likely water, so
relative density = density mercury / density of water = 13600
Answer:
Electrons
Explanation:
Electrons are negatively charged sub-atomic particles, therefore when a body's negatively charged, it means that there's more electrons than protons.