a) What is the rest energy of a neutron, given its mass is 1.6749 x 10^-27 kg?

Give your answer in joules and MeV.

A) 942.56 MeV and 1.605 x 10^-16 J

B) 938.3 MeV and 1.505 x 10^-16 J

C) 939.56 MeV and 1.505 x 10^-16 J

D) 939.56 MeV and 1.502 x 10^-16 J

b) Interstellar space is filled with radiation of 970 x 10^-6 m wavelength. This radiation is considered to be a remnant of the "big bang", the CMB. What is the corresponding blackbody temperature T of this radiation?

T =?