Q4. Add 13.0 g, 0.04 g and 1.52 g, giving the result to the right precision.
The sum is 14.56 g. The least number of decimal places is one (13.0 g), so the result is 14.6 g.
Q5. A constant force of 4.50 N acts parallel to and in the same direction as a displacement of 2.0 m. Find the work done to the right number of significant figures.
W = 4.50 × 2.0 = 9.0 J: two significant figures, set by 2.0 m.
Q6. Round 2.35 and 2.45 to two significant figures by NCERT’s rule.
In 2.35 the preceding digit 3 is odd, so it is raised: 2.4. In 2.45 the preceding digit 4 is even, so it stays: 2.4.