MCQ practice · SSC Physics Board questions · Chapter 5: State of Matter and Pressure
Which is the dimension of density?
Think it through first, then pick an option.
- a L³
- b M⁻¹L³
- c ML³
- d ML⁻³
Answer and explanation
Correct answer: d ML⁻³
ρ = m/V; mass is M and volume is L³, so ρ = M/L³ = ML⁻³. This is the right dimension.
Why the other options are wrong
- a L³: L³ is only the dimension of volume; density also involves mass, so this cannot be the dimension of density.
- b M⁻¹L³: Here mass is below and volume above, the wrong way round; density = mass ÷ volume, so M goes on top and L³ below.
- c ML³: Volume goes in the denominator, so the power of L must be negative; ML³ would mean a product.
More board questions on this topic
- What is the unit of density?
- What is the density of iron in kgm⁻³?
- What is the mass of water in a volume of 20 cm³?
- What is the density of iron?
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