An electron in a hydrogen atom undergoes a transition from the n = 3 level to the n = 6 level. To accomplish this, energy, in the form of light, must be absorbed by the hydrogen atom. Calculate the energy of the light (in kJ/photon) associated with this transition.

Answer;

C.It is the minimum amount of material needed to sustain a fission reaction.

Explanation;

-A critical mass is the smallest or the minimum amount of fissile material needed for a sustained nuclear chain reaction. A critical mass must be achieved in order for the chain reaction to continue and release the atomic energy. A critical mass is needed for both a nuclear reactor and an atomic or hydrogen bomb.

-The critical mass of a fissionable material depends upon its nuclear properties (specifically, the nuclear fission cross section), its density, its shape, its enrichment, its purity, its temperature, and its surroundings.

The correct answer for above statement is:

c.It is the minimum amount of material needed to sustain a fission reaction.

Explanation:

A nuclear reaction is taken into account to be the method during which 2 nuclear paticles (two nuclei or a nucleus and a nucleon) move to supply 2 or a lot of nuclear particles or gamma rays.

Thus, a natural action should cause a change of a minimum of one nuclide to a different. typically if a nucleus interacts with another nucleus or particle while not dynamic the mature of any nuclide, the method is mentioned a nuclear scattering.

The important mass is that the smallest amount of fissile material required to sustain nuclear reactions below expressed conditions

Answer:

elliptical

Explanation:

Nicolaus Copernicus gave the heliocentric theory that sun is at the center if the solar system and all the planets and the moons revolved wound it. according to him, the planets revolved around the sun in circular paths.

But Kepler suggested a different shape of the orbit. According to the laws o planetary motion given by Kepler, the planets revolve around the sun in an elliptical orbit. The sun is at one of its focus.

Answer:

a) They both have the same final speed.

b) Projectile B reaches a greater height

Explanation:

The initial total energy of both projectiles is the same, and since the initial height is zero, that initial energy is entirely kinetic energy:

Now, when the projectiles are going to reach the ground, their height also becomes zero, so the final energy is also entirely kinetic energy:

As stated in the conservation of mechanical energy, the final total energy has to be equal to the initial total energy, and then:

Finally, since the initial speed is the same for both projectiles, they have the same speed when they hit the ground (a).

Next, we know that the height reached by a projectile depends only of their initial vertical velocity, nor their horizontal one. So, the projectile with the highest initial vertical velocity has to reach a greater height. We use trigonometry to calculate that:

It means that projectile B has a higher initial vertical velocity, so it reaches a greater height (b).

This is possible because some of the kinetic energy of both projectiles is never transformed to gravitational potential energy (because is related to the horizontal velocity) and this amount of kinetic energy depends on the angle at which the projectile is launched. As their potential energies at the highest points are different, their maximum heights are, too.