Units and Measurements (NEET)

Question 1

Which of the following measured values has the greatest number of significant figures?

Accepted Answer

D. Leading zeros are never significant; trailing zeros after a decimal point are. 0.0070300 has the significant digits 70300, i.e. 5. 7.030×10⁵ has 4 (the power of ten does not count). 703.0 has 4. In 70300 (no decimal point) the trailing zeros are not significant as per NCERT, so it has 3. Trap: counting all digits of 0.0070300 (8) or treating 70300 as 5 significant figures. Exam pattern: NEET – rul

Question 2

A length is recorded as 4.700 m. Which way of writing it in millimetres preserves exactly the same number of significant figures?

Accepted Answer

C. A change of units must not change the number of significant figures (NCERT). 4.700 m has 4 significant figures. Writing 4700 mm is ambiguous: by the NCERT convention its trailing zeros are not significant, giving only 2. 4.7×10³ mm has 2, and 4700.0 mm wrongly claims 5. Scientific notation 4.700×10³ mm keeps all 4. Exam pattern: NEET – NCERT statement that significant figures do not depend on unit

Question 3

Each of the following numbers is rounded off to three significant figures following the NCERT rules. Which rounding is INCORRECT?

Accepted Answer

D. NCERT rule: if the digit dropped is more than 5 (or 5 followed by non-zero digits), raise the preceding digit; if less than 5, leave it; if exactly 5 (nothing after), raise the preceding digit only if it is odd. 2.745: preceding 4 is even, so 2.74 is correct. 2.735: preceding 3 is odd, so it becomes 2.74, correct. 2.7349: dropped part 49 is less than 5, giving 2.73, correct. 2.7451: dropped part i

Units and Measurements: questions with solutions

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