When 2.0x10^-16 kg of matter is converted into energy how much energy is released

Matter and energy are directly proportional. We know this from the Einstein's equation E=mc², where E is energy, m is mass and c is the speed of light, c=3*10^16 m/s. So lets input the numbers:

E=(2*10^-16)*(3*10^8)²=(2*10^-16)*(9*10^16)=(2*9)*10^0=18 J. So the correct answer is E=18 J. 

Ireally don’t know