Quiz: SI Units and Significant Figures — 14 questions

1. What is the International System of Units (SI)?

A. A traditional measurement system based on fractions

B. A decimal measurement system established in 1960

C. A temperature measurement system based on water

D. A regional measurement system used mainly in the United States

Answer: (B)

Explanation

The SI system is an international decimal measurement system established by the General Conference of Weights and Measures in 1960. The metric system provided its earlier basis, but it is not identical to the modern SI system.

2. Which set lists SI base units for length, mass, time, electric current, temperature, and amount of substance in that order?

A. Kilometer, kilogram, second, ohm, Celsius, liter

B. Meter, kilogram, second, ampere, kelvin, mole

C. Meter, gram, hour, ampere, kelvin, mole

D. Centimeter, gram, minute, volt, Celsius, liter

Answer: (B)

Explanation

The SI base units for these quantities are the meter, kilogram, second, ampere, kelvin, and mole. The gram is commonly used in chemistry, but the kilogram is the SI base unit of mass.

3. What makes a unit a derived unit in the SI system?

A. It replaces a base unit with a smaller laboratory unit

B. It uses a nondecimal scale for a familiar measurement

C. It measures one fundamental quantity without combining units

D. It combines SI base units in a calculated quantity

Answer: (D)

Explanation

A derived unit results from combining SI base units according to a calculated relationship. A base unit, by contrast, represents one fundamental measured quantity.

4. A rectangular box has length $4\,\text{m}$, width $2\,\text{m}$, and height $3\,\text{m}$. What is its volume?

A. $24\,\text{m}^3$

B. $18\,\text{m}^3$

C. $12\,\text{m}^3$

D. $9\,\text{m}^3$

Answer: (A)

Explanation

Volume is found by multiplying length, width, and height: $V=l\times w\times h=4\times2\times3=24\,\text{m}^3$. Adding the three dimensions would not measure three-dimensional space.

5. Which unit is the SI unit for volume?

A. Milliliter

B. Cubic meter

C. Liter

D. Cubic centimeter

Answer: (B)

Explanation

The cubic meter is the SI unit of volume. Cubic centimeters are common for solid objects, while liters and milliliters are frequently used for liquids.

6. Which expression represents a number smaller than one in scientific notation?

A. $620\times10^{1}$

B. $62\times10^{2}$

C. $6.2\times10^{-4}$

D. $6.2\times10^{4}$

Answer: (C)

Explanation

A negative power of ten represents a fraction smaller than one, so $6.2\times10^{-4}$ has that meaning. Positive powers of ten represent multiplication by powers of ten greater than one.

7. How should $10^{-3}$ be interpreted?

A. As the reciprocal of $10^3$

B. As the reciprocal of three multiplied by ten

C. As ten multiplied by negative three

D. As three repeated multiplications by ten

Answer: (A)

Explanation

A negative power is the reciprocal of the corresponding positive power, so $10^{-3}=\frac{1}{10^3}$. Repeated multiplication by ten describes a positive exponent instead.

8. Which metric prefix represents a factor of $10^{-6}$?

A. Pico

B. Nano

C. Milli

D. Micro

Answer: (D)

Explanation

The prefix micro represents $10^{-6}$. Milli represents $10^{-3}$, nano represents $10^{-9}$, and pico represents $10^{-12}$.

9. When converting from a larger metric unit to a smaller metric unit, which way should the decimal point move?

A. To the right by one place regardless of the jumps

B. To the left by the number of metric-unit jumps

C. To the left by one place regardless of the jumps

D. To the right by the number of metric-unit jumps

Answer: (D)

Explanation

Moving toward smaller metric units makes the numerical value larger, so the decimal point shifts right once for each jump. Moving toward larger units shifts it left, so the opposite direction is incorrect.

10. How many meters are equivalent to 4 kilometers?

A. 4,000 meters

B. 0.004 meters

C. 40 meters

D. 400 meters

Answer: (A)

Explanation

A kilometer is three metric-unit jumps larger than a meter, so converting 4 kilometers to meters shifts the decimal three places right to give 4,000 meters. A smaller numerical result would incorrectly treat meters as the larger unit.

11. What do significant figures in a measurement communicate?

A. The measurement's unit conversion factor

B. The measurement's precision

C. The measurement's numerical size alone

D. The instrument's maximum scale value

Answer: (B)

Explanation

Significant figures identify the digits that reflect how precisely a measurement was made. The numerical value by itself does not reveal the precision of the instrument or measurement.

12. When recording a measurement from a marked instrument, which digits should be included?

A. All certain digits plus one estimated digit

B. Only the digits that align exactly with markings

C. The estimated digit followed by the certain digits

D. All certain digits plus two estimated digits

Answer: (A)

Explanation

A recorded measurement includes every digit known from the instrument and one additional digit estimated beyond the smallest marking. The final digit is therefore estimated, while the preceding recorded digits are certain.

13. When adding or subtracting measured values, how should the final result be rounded?

A. To the greatest decimal places among the measurements

B. To the fewest decimal places among the measurements

C. To the fewest significant figures among the measurements

D. To the nearest whole-number place in the result

Answer: (B)

Explanation

Addition and subtraction are rounded according to decimal places, using the measurement with the fewest decimal places. Counting significant figures is the rule for multiplication and division instead.

14. A calculation multiplies 3.2 m by 1.457 m. To how many significant figures should the product be reported?

A. Two significant figures

B. Three significant figures

C. Five significant figures

D. Four significant figures

Answer: (A)

Explanation

Multiplication results are reported with the same number of significant figures as the factor containing the fewest, and 3.2 has two. Decimal-place counting applies to addition and subtraction rather than multiplication.