When did Einstein propose that matter can be converted into energy?

If a 1.0 kg mass is completely converted into energy, how much energy in joules would be released?

Q. Energy is produced by the sun by nuclear fusionreactions inwhich matter is converted into energy. We canmeasure that the Sunproduces energy at the rate of3.80×10²⁶ W.

a. Howmanytons of matter does the Sun loseeachsecond?

b. If it kept losing energy atthisrate, how long would it take the Sun to lose all its mass?