# Physics Questions and Answers – Significant Figures

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This set of Physics Multiple Choice Questions & Answers (MCQs) focuses on “Significant Figures”.

1. The length and breadth of a rectangle are 4.5 mm and 5.9 mm. Keeping the number of significant figures in mind, its area in mm2 is ____
a) 22.55
b) 26.55
c) 26.6
d) 22

Explanation: Area of rectangle is length multiplied by breadth. The area of this rectangle is 4.5×5.9 mm2 = 26.55 mm2.

2. The number of significant digits in 1559.00 is ____
a) 6
b) 5
c) 3
d) 4

Explanation: The number of significant digits is 6. The zeros after the decimal are also significant.

3. The number 0.005900, in standard scientific form can be expressed as ______
a) 5.9×103
b) 59×104
c) 5.9×102
d) 5.9×104

Explanation: Here the number of significant digits is 4. In standard scientific form, we need not consider the zeros after 9 and need to bring the value between 1 and 9 in the first place.

4. Number of significant digits in 0.0028900 is ______
a) 5
b) 6
c) 7
d) 8

Explanation: The correct answer is 5. While calculating the number of significant digits, we need not consider the zero preceding 2.

5. What is the number 75.66852 rounded off to 5 significant digits?
a) 75.67
b) 75.669
c) 75.668
d) 75.667

Explanation: According to the rounding off rules, if the digit to be removed is 5 and the following digit is not zero, then the last remaining digit is increased by one.
Given number = 75.66852
After applying rounding rules, 852 rounds off to 9
Hence, the final answer will be “75.669”.

6. The length of a cube is 2.3 cm. What is its volume rounded off to 4 significant digits in cm3?
a) 12.67
b) 12.167
c) 12.17
d) 13

Explanation: Volume of a cube is equaled to its length cubed, therefore, required volume = 12.167 cm3. The 67 in the end will be rounded off to 7, hence the final number becomes 12.17.

7. How many significant digits are there in 25.33600?
a) 7
b) 8
c) 5
d) 6

Explanation: The correct answer is 7. The zeros after 6 in the decimal part are also significant.

8. The number of significant digits in 5.002 is ____
a) 5
b) 4
c) 3
d) 6

Explanation: The correct answer is 4. All the digits in the given number are significant.

9. The volume of a box, 10 m wide, 4.5m, long and 2.3 m high up to 3 significant digits in m3 is ____
a) 104
b) 103.5
c) 103
d) 100

Explanation: The volume of the box is length x width x height = 103.5. This number, rounded off to 3 significant digits becomes 104.

10. How many significant digits are there in 002.5001?
a) 1
b) 5
c) 7
d) 6 