9. Calculate the gravitational force and electric force between the nucleus of a Helium atom and an electron in its orbit. The atomic mass of Helium is 4.0. Its atomic number is 2.0. The
distance between the nucleus and the electron in its orbit is 0.5 x 10
10m.

would be false hope this out

like poles repel so keep pushing north to north and repels funny to see this

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m