The volume of a 150.0-gram sample of copper at 298 K and 101.3 kPa is 16.7 cm3.
- Mayya Alocci
- Jun 19
- 1 min read
Regents Chemistry Exam January 2025 Question 39
39 The volume of a 150.0-gram sample of copper at 298 K and 101.3 kPa is 16.7 cm3. The mass of the copper sample is expressed to how many significant figures?
(1) 1 (3) 3
(2) 2 (4) 4
Solution:
The rules for significant figures are :
All non-zero digits are significant. This means all numbers: 1,2,3,4,5,6,7,8, and 9 are significant. For example 5.67 has 3 significant figures.
All zeroes in between non-zero numbers are significant. For example zero in 303 is significant.
Leading zeroes (zeroes to the left of a number) are not significant. For example: 0.0009 has only one significant figure (9) since all of the zeroes to the left of it are not significant.
Trailing zeros to the right of a decimal point are significant. For example zeroes in 3.400 are significant.
150.0 has 4 significant figures. Choice 4 is the correct answer.
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