In two or more complete sentences describe how atomic radius changes as you move down a group in the periodic table and why.

When we move across the period from left to right then there is decrease in atomic raduis.

This is due to increase in number of protons and electrons across a period.

Since electrons are added in same energy level, therefore, they get pulled closer to the nuvleus because of more number of protons which carry a positive charge.

As a result, there is shrinkage in size from left to right across the period.

the temperature of the gas, in k, not celsius.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.