Agouy balance is used to determine the magnetic susceptibility of a substance. a strong electromagnet is placed next to the sample, which is on a balance. if the sample is paramagnetic, the mass reading of the balance will increase when the field is switched on. based on their electron configurations, predict whether these elements are paramagnetic or diamagnetic.
paramagnetic
he ,mg ,s ,li

Paramagnetic - S , Li

Diamagnetic - He , Mg

Explanation:

Paramagnetic are those which has unpaired electrons and diamagnetic are those in which all electrons are paired.

Given

He, the atomic number - 2

The electronic configuration is -  

The electrons in 1s orbital = 2 (Paired)

Thus, the element is diamagnetic as the electrons are paired.

Mg, the atomic number - 12

The electronic configuration is -  

The electrons in 3s orbital = 2 (Paired)

Thus, the element is diamagnetic as the electrons are paired.

S, the atomic number - 16

The electronic configuration is -  

The electrons in 3p orbital = 4 (Unpaired)

Thus, the element is paramagnetic as the electrons are unpaired.

Li, the atomic number - 3

The electronic configuration is -  

The electrons in 2s orbital = 1 (Unpaired)

Thus, the element is paramagnetic as the electrons are unpaired.

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.