1) Frequency: 
the energy of the photon absorbed must be equal to the ionization enegy of the atom, which is

The energy of a photon is given by

where
is the Planck's constant. By using the energy written above and by re-arranging thsi formula, we can calculate the frequency of the photon:

2) Wavelength: 91.2 nm
The wavelength of the photon can be found from its frequency, by using the following relationship:

where
is the speed of light and f is the frequency. Substituting the frequency, we find

Answer:
Explanation:
1. Frictional force is responsible for running of car and buses on roads.
2.Gravitational force exists between astronauts in space.
3. Magnetic for is responsible to attract the iron objects using a magnet
4.Electrostatic force is responsible for fiber to stick on the skin.This force occurs due to the presence of charge.
5.When a person is pushing a trolley then object experience a normal reaction from ground.
6.Gravitational force makes the planet to move in their orbits.
Answer:
Molecules speed up
Explanation:
This is caused because of the temperature increasing. The temperature increase is telling us that the thermal energy of the reaction is increasing. When the energy is increased molecules increase their speed, because they have more energy in them
The answer is A) 1000 J
According to the law of conservation of energy, the total energy before an action is always equal to the total energy after the action.
So that is, the total energy is 8000J found as potential energy, 7000J has transformed into kinetic energy, then the thermal energy should be the remaining 1000J.
Hope this helps.
Answer:
1.30
Explanation:
To calculate the critical angle we have ti use the formula:

where theta_c is the critical angle, n1 is the index of refraction of the material where the light is totally reflected, and n2 is the refractive index of the other material.
By taking n_2 and replacing we obtain:

hope this helps!!