Answer:
N> As> Ga
Step-by-step explanation:
There are two important factors that come into play when we are discussing the strength of attraction between protons and valence electrons;
1) distance of the valence electrons from the nucleus
2) size of the nuclear charge
If we consider the elements; nitrogen, arsenic and gallium, nitrogen is in period 2. This implies that it has only two shells. The valence electrons are closer to the nucleus and are more strongly attracted to the protons in the nucleus.
Arsenic and gallium are both in period 4. This implies that they both contain a total of 4 electron shells. However, arsenic has a nuclear charge of 33 protons while gallium has a nuclear charge of 31 protons. Hence arsenic has a greater size of nuclear charge than gallium. The attraction between protons and valence electrons in arsenic is therefore greater than it is in gallium.