How many photons will be required to raise the temperature of 2.0 g of water by 2.5 K?

Answer 1

Do you happen to know the wavelength or frequency of the photons?

If you do then use E=hf to give you the energy of one photon.

specific heat of water is 4.18 J/g/K

so energy required is
4.18 x 2.0 x 2.5 J

divide this value by the energy of one photon.

Answer 2

an electron jumps from the sixth energy level to the second energy level.

Determine the energy change associated with this eled=ctron trasition.