Find the odd one out.

The correct answer is B. Litres is the odd one out because it measures volume, while Grams, Tonnes and Quintals all measure mass.

• Grams is a unit of mass, one-thousandth of a kilogram. The kilogram is the SI base unit of mass.
• Tonnes is a metric unit of mass equal to 1000 kg, used for bulk trade, freight and shipping.
• Quintals is a unit of mass equal to 100 kg. Crop prices and MSP are quoted per quintal in India, so it appears often in agriculture questions.

Litres is the unit of volume, equal to one cubic decimetre. That is why it is the odd one out here.

The core concept is the distinction between mass and volume, both under the metric system India follows through the Legal Metrology Act, 2009, which replaced the Standards of Weights and Measures Act, 1976. For Mains, the link is agricultural marketing, where quintal-based pricing affects farmers directly.

Trap: Candidates often eliminate Quintals because it sounds like a local, non-SI measure. Ask first which physical quantity each unit measures, not whether it is an SI unit.