Explanation:
1) The valence electrons of group 4A elements are in the 5s subshell.
The given statement is false .
The valence electrons of group 4A elements are in the ns and np subshell .Where n is equal to 1 to 7.
2) Period 3 elements have an inner electron configuration of [Ar].
The given statement is false .
The noble gas which comes before third period is neon.Period 3 elements have an inner electron configuration of [Ne].
3)The highest principal quantum number of period 4 elements is 4.
The given statement is true.
The period number of periodic table indicates the value of highest principal quantum number.
4) Period 5 elements have six 4p electrons.
The given statement is true.
This so because 4p subshell is filled before filling of shells of fifth shell. So, the 4p subshell will obviously have 6 electrons.
5) Period 5 elements have an inner electron configuration of (Kr).
The given statement is true.
The noble gas which comes before third period is krypton .
6) Group 8A elements have full outer principal s and p subshells.
The given statement is true.
This is because the the group mentioned in the statement if noble gases and noble gases are inert in nature due to fully filled electronic configurations.
7) The valence electrons of group 3A elements are in an s and p subshell.
The given statement is true.
The valence electrons of group 3A elements are in the ns and np subshell .Where n is equal to 1 to 7. there general electronic configuration is .
8) The highest principal quantum number of period 4 elements is 5
The given statement is false.
The period number of periodic table indicates the value of highest principal quantum number.