If a proton and anti-proton come close to each other and annihilate, how much energy will be released

$3 \times 10^{-10}$ J

Mass of proton = mass of antiproton = 1.67 × 10^-27 kg = 1 amu

Energy equivalent to 1 amu = 931 MeV

So energy equivalent to 2 amu = 2 × 931 MeV

$=1862 \times 10^6 \times 1.6 \times 10^{-19}=2.97 \times 10^{-10} \mathrm{~J}=3 \times 10^{-10}$ J