Answer:
n = 1.42
Explanation:
The refractive index for a medium is given by the ratio of the speed of light in vacuum to the speed of light in a medium.

So, the refractive index of the medium is 1.42.
Answer: Option 2
Explanation:
Option 1 is wrong because there are 2 protons and 2 neutrons in nucleus.
Option 3 is wrong because there are two electrons moving around nucleus.
Option 4 is wrong because electrons are negatively charged and are moving around the nucleus.
Option 5 is wrong because there equal amount of protons and electrons with 2 each.
<u>Answer:</u> The angle of diffraction is 0.498°
<u>Explanation:</u>
To calculate the angle of diffraction, we use the equation given by Bragg, which is:

where,
n = order of diffraction = 3
= wavelength of the light =
(Conversion factor:
)
d = spacing between the crystal planes = 0.100 mm =
(Conversion factor: 1 m = 1000 mm)
= angle of diffraction = ?
Putting values in above equation:

Hence, the angle of diffraction is 0.498°
Answer: option A. strong nuclear force.
Explanation:
The diagram shows the subatomic particles inside the nucelous: protons and neutrons.
As you know, the protons are positively charged partilces inside the nucleous.
Being those particles charged with the same kind of charge they experiment electrostatic repulsion. So, how do you explain that they can stand together in such small space as it is the nucleous?
The responsible of keeping the subatomic particles together is the so called strong nuclear force.
Strong nuclear force or simply strong force is one of the four fundamental interactions or forces: i) gravitational, ii) electromagnetic, iii) weak nuclear force, and iv) strong nuclear force.
Strong nuclear force is the strongest force of nature and acts only in short distances as those inside the nucleous and is responsible for both the atraction among quarks and the atraction among protons to bind them together inside the atomic nucleous.