What was daltons motivation for proposing his model of the atom

John Dalton based his partial pressures theory on the idea that only like atoms repel one another, Whereas unlike atoms appear to react indifferently. This notion was erroneous, but it helped to explain why each gas in a mixture behaved independently, serving the purpose of showing that atoms of all kinds are not alike.

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.

the correct answer would be d. hope this !