<u>Answer: </u>The correct statement is X is the effective nuclear charge, and it increases across a period.
<u>Explanation:</u>
We are given that:
X = number of protons − number of core electrons
Effective nuclear charge is defined as the actual nuclear charge (Z = number of protons) minus the screening effect caused by the electrons present between nucleus and valence electrons. These electrons are the core electrons.
The formula used for the calculation of effective nuclear charge given by Slater is:

where,
= effective nuclear charge
Z = atomic number or actual nuclear charge or number of protons
= Screening constant
The effective nuclear charge increases as we go from left to right in a period because nuclear charge increases with no effective increase in screening constant.
Hence, the correct answer is X is the effective nuclear charge, and it increases across a period.
Answer:
it is good for thermoelectric power plant cooling
it means that there is a lot of salt in the water
Someone would remove salt from water to be able to drink it
lastly, salt can be removed from water with reverse osmosis systems
Hello!
Your answer is A.. Earth's core is the most dense layer and it consists of the outer core and the inner core.
Hope this helps :))
The homologous structures and the analogous structures of different species.
Tearing paper, Physical Change