Answer: Option (c) is the correct answer.
Explanation:
A positron is denoted as
, a neutron is denoted as
, an electron is denoted as
, and a proton is denoted as
.
Therefore, when
will decay into
this means there occurs decrease in its mass number. Hence, it means a neutron will be releasing during this reaction.
The reaction will be as follows.

Reactivity. It is the ability of matter to combine chemically with other substances.
Answer: The standard free energy change for a reaction in an electrolytic cell is always positive.
Explanation:
Electrolytic cells use electric currents to drive a non-spontaneous reaction forward.
Relation of standard free energy change and emf of cell

where,
= standard free energy change
n= no of electrons gained or lost
F= faraday's constant
= standard emf
= standard emf = -ve , for non spontaneous reaction
Thus 
Thus standard free energy change for a reaction in an electrolytic cell is always positive.