partial pressure

Will the partial pressure of O2 and N2 change?

No, they will not change.

Explanation 1:
The partial pressure of O2/N2 is the pressure that the gas exerts if O2/N2 is present alone in the same container at the same temperature. Since the number of moles of of O2/N2 and all other conditions are constant, the partial pressure of O2/N2 remains unchanged.

Experiment 2:
For O2 or N2: Partial pressure, p = nRT/V
All of the number of moles of O2/N2 (n), gas constant (R), temperature (T) and volume (V) are constant, the partial pressure remains unchanged.

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(1) volume ratio remains unchanged, so mole fraction remains unchanged.

(1) is incorrect.
Both the volume fraction and mole fraction are changed.

Before CO2 is absorbed:
Volume ratio N2 : O2­ : CO2 = 40 : 35 : 25
Mole fraction of N2 = (40/100) x 100% = 40%
Mole fraction of O2 = (35/100) x 100% = 35%
Mole fraction of CO2 = (25/100) x 100% = 25%

After CO2 is absorbed:
Volume fraction of N2 : O2 : CO2 = 40 : 35 : 0
Mole fraction of N2 = (40/75) x 100% = 53.3%
Mole fraction of O2 = (35/75) x 100% = 46.7%

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(2) mole fraction = mole of N2orO2 / total mole
(2) total mole increase or decrease,
(2) it depends on whether mole fraction increase or decrease

(2) is incorrect.

Mole fraction of N2/O2 = (No. of moles of N2/O2) / (Total no. of moles)
The mole fraction of N2/O2 is a dependent variable.

In other words, the mole fraction of N2/O2 depends on its number of moles and the total number of moles. It is incorrect to state that "the total number of moles does not depend on the mole fraction."