Answer:
The energy absorbed by a hydrogen atom is 1.549 X10⁻¹⁹ J
Explanation:
Using Bohr's equation; the energy absorbed by the hydrogen atom can be calculated as follows:

When an electron moves from a lower energy level to a higher energy level, energy is absorbed by the atom.
Lower energy level (n₂) = 3
Higher energy level (n₁) = 5
1 eV = 1.602X10⁻¹⁹ C

ΔE = 1.549 X10⁻¹⁹J
The energy absorbed by a hydrogen atom to transition an electron from n = 3 to n = 5 is 1.549 X10⁻¹⁹ J
Answer:

Solution:
As per the question:
Point charge, q = 
Test charge, 
Work done by the electric force, 
Now,
We know that the electric potential at a point is given by:

where
r = separation distance between the charges.
Also,
The work done by the electric force i moving a test charge from point A to B in an electric field:




I think it is either D) or E)
But i am going to go with E)
Answer:
13.7m
Explanation:
Since there's no external force acting on the astronaut or the satellite, the momentum must be conserved before and after the push. Since both are at rest before, momentum is 0.
After the push

Where
is the mass of the astronaut,
is the mass of the satellite,
is the speed of the satellite. We can calculate the speed
of the astronaut:

So the astronaut has a opposite direction with the satellite motion, which is further away from the shuttle. Since it takes 7.5 s for the astronaut to make contact with the shuttle, the distance would be
d = vt = 1.83 * 7.5 = 13.7 m
B)
If it is known that the atomic number is 8, we know that the electrons are also 8. Since the atomic mass (O18) is 18, the neutrons are 18-8=10. Option B is the correct answer.
Hope I helped :)