Question

physics unit 1 assessment a
section 1: multiple choice (1 point each)

1. how many significant figures are in the number 0.00340?

a. 5 b. 2 c. 3 d. 4

1. in the number 0.00450, which zeros are significant?

a. the last two zeros only b. all zeros c. no zeros d. the last zero only

1. what is the correct number of significant figures in the result of 12.1×3.12?

a. 2 b. 3 c. 4 d. 5

1. in the number 0.00450, which zeros are significant?

a. the last two zeros only b. all zeros c. no zeros d. the last zero only

1. which measurement has three significant figures?

a. 0.0304 b. 3.40 c. 0.030 d. 3000

Explanation:

Step1: Recall significant - figure rules

Leading zeros (zeros before non - zero digits) are not significant. Trailing zeros (zeros after non - zero digits) are significant if there is a decimal point.

Step2: Analyze 0.00340

Leading zeros are not significant. The non - zero digits 3 and 4 and the trailing zero are significant. So there are 3 significant figures.

Step3: Analyze 0.00450

Leading zeros are not significant. Only the last zero (after 4 and 5) is significant as there is a decimal point.

Step4: Calculate 12.1×3.12

$12.1\times3.12 = 37.752$. In multiplication, the result should have the same number of significant figures as the number with the least significant figures among the factors. 12.1 has 3 significant figures and 3.12 has 3 significant figures. So the result should have 3 significant figures.

Step5: Analyze options for three - significant - figure measurement

For 0.0304, the leading zero is not significant, and it has 3 significant figures. For 3.40, it has 3 significant figures. For 0.030, it has 2 significant figures. For 3000, it has 1 significant figure (if no decimal point is shown).

Answer:

1. c. 3
2. d. The last zero only
3. b. 3
4. d. The last zero only
5. a. 0.0304, b. 3.40