Free Measurements MCQs with Answers

21. The final answer of the expression is:

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: The following is the solution:In multiplication and division, the final result is limited to numbers containing the least number of significant figures.The least precise terms i.e., 9.0 has only two significant figures. Hence, the final answer will have two significant figures.(29−20.2) It consists of two numbers, 29→ has two significant figures and 20.2→ has three significant figures. The final result of this expression should have Two Significant Figures 1.79 x 10⁵ In scientific notation, the number of significant figures is taken from the non-exponent part of the number. 1.79 has three significant figures. The least of all is 2. So, the final result must be stated in scientific notation with two significant figures

22. How many significant figures are there in 0.4793?

• A. 3
• B. 4
• C. 5
• D. 6

Explanation: The following is the solution: The number 0.4793 has four significant figures. In the context of significant figures: Non-zero digits are always considered significant. In this case, 4, 7, 9, and 3 are non-zero digits. Zeros between significant digits are also considered significant. There are no zeros between the significant digits in 0.4793. Leading zeros (zeros to the left of the first non-zero digit) are not considered significant. In this case, there are no leading zeros. Trailing zeros (zeros to the right of the last non-zero digit) in a decimal number are considered significant. In 0.4793, the zero after 3 is a trailing zero and is considered significant. Therefore, all four digits in 0.4793 are considered significant, making it a number with four significant figures.

23. In SI units, the unit of Candela is used for the measurement of:

• A. Heat intensity
• B. Light intensity
• C. Energy/time
• D. Energy/area

Explanation: The Candela is specifically a unit for measuring luminous intensity, which is the amount of light emitted in a particular direction. This measurement takes into account the sensitivity of the human eye to different wavelengths of light. Luminous intensity is important in applications where the visual perception of light is crucial, such as lighting design, optics, and photometry.

24. Which of the following is not a base unit in the SI system?

• A. Ampere
• B. Second
• C. Meter per second
• D. Candela

Explanation: In summary, the correct answer is option c) Meter per second, as it is not a base unit in the SI system. The other options (a, b, and d) represent base units: ampere for electric current, second for time, and candela for luminous intensity.

25. The number L = 8.0 x 10^4 cm can be expressed as:

• A. L = 8.0 x 10^6 mm
• B. L = 0.8 km
• C. L = 0.8 x 10^2 m
• D. L = 8.0 x 10^3 m

Explanation: B is the answer as converting 80000 cm to meters would give us 800 m as we divide 80000 cm by 100 cm/m. Converting meters to kilometers, we must divide 800 m by 1000 m/km to get 0.8 km

26. The base units of Young's Modulus are:

• A. kg m-1 s-2
• B. kg m-2 s-2
• C. kg m-3 s-2
• D. kg ms-3

Explanation: The Young modulus is basically the stress over strain where stress is force/area and the strain has no units. Simplifying the units of Force, N would give us kg ms-2. Dividing it by m2 of the area would give us kg s-2m-1 so, the answer is A.

27. Which of the following is dimensionless quantity?

• A. Power
• B. Frequency
• C. Refractive Index
• D. Impulse

Explanation: Option A: Power is the rate at which energy is transferred. It is measured in watts, which are equivalent to joules per second. Option B: Frequency is the number of oscillations per unit time. It is measured in hertz, which are equivalent to cycles per second. Option C: The refractive index is a dimensionless quantity.A dimensionless quantity is a quantity that has no units. It is a pure number that is independent of any physical dimensions.The refractive index is a measure of how much a light beam bends when it passes from one medium to another. It is defined as the ratio of the speed of light in a vacuum to the speed of light in the medium.The refractive index has no units because it is a ratio of two quantities with the same units. The speed of light in a vacuum is a physical quantity with units of meters per second. The speed of light in a medium is also a physical quantity with units of meters per second. Option D: Impulse is the product of force and time. It is measured in newton-seconds.

28. Which of the following is not a S.I. base quantity:

• A. Mass
• B. Intensity of light
• C. Velocity
• D. Length

Explanation: Option A: Mass (kilogram, kg) is the amount of matter in an object. It is a fundamental property of matter that does not depend on the object's location or motion. Option B: Intensity of light (candela, cd) is the amount of light emitted from a source in a particular direction. It is a measure of the brightness of light. Option C: Velocity is a derived quantity, which means that it can be expressed in terms of the SI base quantities. For example, velocity is equal to the distance traveled divided by the time it takes to travel that distance, so it can be expressed in terms of the base quantities of length and time. Option D: Length (meter, m) is the distance between two points. It is a fundamental property of space that does not depend on the location or motion of the points.

29. The length and width of a rectangular plate are measured to be 15.3 mm and 12.50 mm. Find the area of the plate up to an appropriate number of significant figures:

• A. 191.25 mm2
• B. 195.8 mm2
• C. 196 mm2
• D. 200 mm2

Explanation: The following is the solution:Here are the "significant figure" rules: When adding or subtracting quantities, the sum/difference should be rounded to the number of decimal places as the term with the fewest number of decimal places. When multiplying or dividing, the answer =15.3 x 12.50= 191.25 mm2Since the width (12.50) is in 4 sig figures and the length (15.3) is in 3 sig figs the answer should be rounded off according to the least number of significant figures which is 3, which would give us 191 but since that isn't given in the options our only option is A. The rest of the options are completely wrong as 191.25 cannot be rounded off to any of the mentioned numbers according to the significant figures in the given values in the question.

30. Determine the significant figures in 0.0085:

• A. 4
• B. 3
• C. 2
• D. 1

Explanation: Some of the basics rules for significant figures are:All non-zero digits are significant.Zeros between non-zero digits are significant.A trailing zero or final zero in the decimal portion only are significant.