Any chemical or physical change that absorbs energy 1. cannot occur spontaneously. 2. forms products with less mass than the initial reactants. 3. is an endothermic process. 4. has high activation energy.

3. is an endothermic process.

Explanation:

Generally, reactions can be classified into two. Depending on whether they absorb heat -energy or release energy.

Endothermic Reactions are those reactions in which the reaction absorb heat form the surroundings.

Exothermic reactions are those reactions that release heat to the surroundings.

This means the correct option is;

3. is an endothermic process.

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.