Question

Consider the following A) 0.0025 B) 500.0 C) 2.0034 Number of significant figures in A, B and C respectively, are

• A. 5, 4, 4
• B. 2, 4, 2
• C. 4, 3, 2
• D. 2, 4, 5

Hint:

Significant figures rules: - Non-zero digits: Always significant. - Zeros between non-zeros: Always significant (e.g., 101 has 3 s.f.). - Leading zeros: Never significant (e.g., 0.025 has 2 s.f.). They are placeholders. - Trailing zeros: - With a decimal point: Significant (e.g., 2.500 has 4 s.f.; 500.0 has 4 s.f.). - Without a decimal point: Ambiguous (e.g., 500). Use scientific notation (e.g., \(5 \times 10^2\) for 1 s.f., \(5.0 \times 10^2\) for 2 s.f., \(5.00 \times 10^2\) for 3 s.f.) or place a decimal (500. for 3 s.f.).

Answer 1

The Correct Option is D

Rules for determining significant figures: 1.
Non-zero digits are always significant.
2.
Zeros between non-zero digits are significant.
3.
Leading zeros (zeros to the left of the first non-zero digit) are not significant.
They only indicate the position of the decimal point.
4.
Trailing zeros in a number with a decimal point are significant.
5.
Trailing zeros in a number without a decimal point are ambiguous (e.
g.
, 500 could have 1, 2, or 3 s.
f.
).
Scientific notation or an explicit decimal point (like 500.
) removes ambiguity.
A) 0.
0025 - The leading zeros (0.
00) are not significant.
- The non-zero digits 2 and 5 are significant.
- Number of significant figures = 2.
B) 500.
0 - The non-zero digit 5 is significant.
- The zeros between 5 and the decimal point are significant because of the trailing zero after the decimal point.
- The trailing zero after the decimal point (500.
0) is significant.
- All digits 5, 0, 0, 0 are significant.
- Number of significant figures = 4.
C) 2.
0034 - The non-zero digits 2, 3, 4 are significant.
- The zeros between 2 and 3 (2.
0034) are significant.
- All digits 2, 0, 0, 3, 4 are significant.
- Number of significant figures = 5.
So, the number of significant figures in A, B, and C are 2, 4, and 5, respectively.
This matches option (4).