The following illustration shows four body systems. Siobhan’s science teacher asks her to identify the two organ systems that work together to provide cells with oxygen and to remove carbon dioxide. Which two systems should Siobhan list?

system 1 and system 2
system 1 and system 4
system 2 and system 3
system 3 and system 4

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

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.