what element is missing in the following nuclear equation?

212/84 po → 208/82 ? + 4/2 he

The missing part in the nuclear reaction is Pb.

Explanation:

The given nuclear reaction is a type of alpha decay process. In this process, the nucleus decays by releasing an alpha particle. The mass number of the nucleus is reduced by 4 units and atomic number is also decreased by 2 units. The particle released is a helium nucleus.

The general equation representing alpha decay process is:

For the given equation of a nuclear reaction:

The nucleus having atomic number of 82 is Lead and the symbol used to represent this element is 'Pb'

Thus, the missing part in the nuclear reaction is Pb.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.