Verified Solution • 2025–26 Session moderate

Q1.12: NCERT Physics - Part 1 UNITS AND MEASUREMENT 1.12 Solution: The mass of a box measured by a grocer's balance is 2.30 kg.…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often add the kilogram reading directly to the gram readings without first converting all quantities to the same unit, leading to a wrong total and incorrect significant‑figure rounding. Convert every mass to either kg or g before performing the sum, then round the result according to the least precise measurement (here the 2.30 kg limits the answer to three significant figures).

The mass of a box measured by a grocer's balance is 2.30 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to the box. What is (a) the total mass of the box, (b) the difference in the masses of the pieces to correct significant figures?

Step-by-Step Verified Solution

**Answer:** (a) 2.34 kg (b) 0.02 g **Step-by-Step Explanation:** (a) Total mass = 2.30 kg+0.02015 kg+0.02017 kg=2.34032 kg≈2.34 kg2.30 \text{ kg} + 0.02015 \text{ kg} + 0.02017 \text{ kg} = 2.34032 \text{ kg} \approx 2.34 \text{ kg} (limited by 2.30 kg which has 3 sig figs). (b) Difference = 20.17−20.15=0.02 g20.17 - 20.15 = 0.02 \text{ g} (1 significant figure).

All Questions in this Chapter

Q1.1 Q1.2 Q1.3 Q1.4 Q1.5 Q1.6 Q1.7 Q1.8 Q1.9 Q1.10 Q1.11 Q1.12 Q1.13 Q1.14 Q1.15 Q1.16 Q1.17

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