An empirical formula: 1. gives the relative number of ions of each element per formula unit. 2. gives the number of ions of each element per formula unit. 3. uses lines to represent covalent bonds and shows how atoms in a molecule connect or bond to each other. 4. gives the relative number of atoms of each element per formula unit.5. gives the actual number of atoms of each element per formula unit.

4.  gives the relative number of atoms of each element per formula unit

Explanation:

An empirical formula -

It refers to the formula which determined the simplest whole - number ratio of all the atoms in a given species , is referred to as an empirical formula .

In simple terms ,

It is he smallest formula of the whole number which when multiplied by some whole number gives the actual structure of the compound .

Hence , from the given information of the question ,

The correct option for empirical formula is 4.

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.