The quantity with the dimension ML⁻¹T⁻² is- which of the following is correct?

Correct answer: d i, ii and iii

Right. Pressure and stress are force ÷ area, and the modulus is stress ÷ strain with no dimension for strain. All three are ML⁻¹T⁻².

Why the other options are wrong

• a i and ii: iii is true too but is left out: modulus = stress ÷ strain and strain has no dimension, so the modulus is also ML⁻¹T⁻².
• b i and iii: ii is true too but is left out: stress = force ÷ area = ML⁻¹T⁻².
• c ii and iii: i is true too but is left out: pressure = force ÷ area = ML⁻¹T⁻².