Units and Conversion
A. Micro
B. Milli
C. Centi
D. Kilo
Answer is B: “Milli” refers to the thousandth or 10−3 (nothing to do with a million!).
2. Which of the following does NOT describe a milligram?
A. 1 × 103 g
B. 1 × 10−3 g
C. One-thousandth of a gram
D. 0.001 g
Answer is A: This (1 × 103 g) is 1000 g = 1 kg.
3. How many micrograms are there in 5 mg?
A. 0.005
B. 0.5
C. 500
D. 5000
Answer is D: 1 mg is 1000 μg, so 5 mg = 5000 μg.
4. Given that a milligram is 1 × 10−3 g, what is a microgram?
A. 1 × 103 g
B. 1000 mg
C. 1 × 10−6 g
D. 0.001 g
Answer is C: A microgram is one millionth (0.000001 or 10−6) of a gram. A = 1 kg; B = 1 g; D = 1 mg.
5. How many micrograms are there in 1 mg?
A. 0.001
B. 0.1
C. 100
D. 1000
Answer is D: 1 μg = 10−3 × 1 mg, so 1000 μg is the same as 1 mg.
6. How many milligrams are there in 1 μg?
A. 0.001
B. 1000
C. 0.1
D. 1,000,000
Answer is A. 1 mg = 103 × 1 μg, so one-thousandth of a milligram is the same as 1 μg.
7. Which of the following units is NOT part of the Australian Metric System of units?
A. Millimetre of mercury for measuring blood pressure
B. Degree Celsius for measuring temperature
C. Pascal for measuring pressure
D. Second for measuring time
Answer is A: Pascal (Pa) is the SI unit for pressure.
8. In the Australian Metric System of units, what does the prefix micro stand for?
A. 1000
B. One thousandth
C. 1,000,000
D. One millionth
Answer is D: One millionth = 10−6
9. What is 3400 cm2 converted to square metres?
A. 0.0034 m2
B. 0.34 m2
C. 3.4 m2
D. 34 m2
Answer is B: A square metre has sides that are 100 cm long, so 100 × 100 = 10,000 cm2 in a square metre. So 3400/10,000 = 0.34.
10. In the Australian Metric System of measurement, what does the prefix “milli” stand for?
A. One thousandth
B. 1000
C. One millionth
D. 1,000,000
Answer is A: Milli = one thousandth = 10−3
11. What is 120 mg expressed as grams?
A. 0.12 g
B. 1.2 g
C. 12 g
D. 12,000 g
Answer is A: 1 mg is a thousandth of a gram (0.001 g), so 120 mg is 120 thousandths= 0.120 (Milligram to gram: shift the decimal point three places to the left.)
12. How many milligrams are in 0.75 g?
A. 0.00075 mg
B. 7.5 mg
C. 75 mg
D. 750 mg
Answer is D: 1 g is 1000 mg. So three-quarters of a gram is three-quarters of a thousand milligrams = 750 mg. (Gram to milligram: shift the decimal point three places to the right.)
13. What is 1.25 g converted to micrograms?
A. 125
B. 1250
C. 12,500
D. 1,250,000
Answer is D: Micro refers to “a millionth of”. There are 1.25 × 106 millionths of a gram in 1.25 g. So 1,250,000 millionths of a gram = 1,250,000 μg. (Gram to microgram: shift the decimal point six places to the right.)
14. How many micrograms are there in 0.25 g?
A. 250
B. 25,000
C. 250,000
D. 25,000,000
Answer is C: Micrograms are smaller than grams, so there will be more of them. A million times more, so 0.25 × 106 = 250,000 μg. (Gram to microgram: shift the decimal point six places to the right.)
15. When 2.25 mg is converted to micrograms, how many micrograms are there?
A. 22.5
B. 2250
C. 225,000
D. 22,500,000
Answer is B: There are 1000 μg in each milligram. Hence 2.25 thousand is 2250. (Milligram to microgram: shift the decimal point three places to the right.)
16. What is the result of converting 650 μg to milligrams?
A. 0.650
B. 6.50
C. 65
D. 65,000
Answer is A: 1000 μg are needed to make a milligram, so we have less than one. (Microgram to milligram: shift the decimal point three places to the left.)
17. Given that 1 mmHg = 0.133 kPa, how can a systolic BP measurement of 120 mmHg be converted to a measurement in kilopascal?
A. Divide 120 by 0.133
B. Multiply 120 by 0.133
C. Divide 0.133 by 120
D. Add 0.133–120
Answer is B: We know that 1 mmHg is the same as 0.133 kPa, so two of them would be 2 × 0.133 = 0.266 kPa. Hence 120 of them would be 120 × 0.133 = 16 kPa
18. A newborn baby weighs 7 lb 8 oz (seven pounds and eight ounces). If 1 lb = 0.454 kg, what is done to convert the baby’s weight to kilograms?
A. Multiply 7.8 by 0.454
B. Divide 7.8 by 0.454
C. Divide 7.5 by 0.454
D. Multiply 7.5 by 0.454
Answer is D: You need to know that 8 oz is half a pound and that “a half” is the same as 0.5! Hence, 7 lb 8 oz = 7.5 pounds = 7.5 × 0.454 = 3.4 kg
19. By Internet search, you discover that 1 in. (1″) is the same as 2.54 cm. How would you convert a man’s waist girth (circumference) from 40″ to centimetres?
A. Multiply 40 by 2.54
B. Divide 40 by 2.54
C. Divide 2.54 by 40
D. Multiply 40.1 by 2.54
Answer is A: You know that 1″ is the same as 2.54 cm, so ten of them would be 10 × 2.54 = 25.4 cm. Hence, 40 of them would be 40 × 2.54 = 110.6 cm.
20. A clinical thermometer is used to measure someone’s body temperature to be 101 °F (Fahrenheit). When this temperature is converted to degrees Celsius using the conversion formula: T (°C) = (T (°F) − 32) × 5/9, what is the correct value?
A. −6.5
B. 38.3
C. 82
D. 124
Answer is B: Centigrade temperature values above zero are always smaller than Fahrenheit values. T (°C) = (T (°F) − 32) × 5/9 = (101 − 32) × 5/9 = 69 × 5/9 = 34 5/9 = 38.3 °C
21. Match the following “power of 10” notations: 10−2, 10−3, 103, 10−6, 106 with the appropriate SI unit prefixes given below:
A. Milli, centi, mega, kilo, micro
B. Centi, milli, kilo, micro, mega
C. Centi, kilo, milli, micro, mega
D. Milli, centi, kilo, mega, micro
Answer is B: One hundredth is “centi” and one thousandth is “milli”.
22. What is meant by the “Systeme Internationale” (SI) units that are used to measure quantities?
A. They are the British Imperial units of the foot, pound, gallon, degree Fahrenheit, mile, etc.
B. They are the USA customary units of a nautical mile, hundredweight, furlong, bushel, etc.
C. They are the technical units such as atmospheres, calories, teaspoons, thou of an inch, etc.
D. They are the standard international system based on the metre, kilogram, ampere, kelvin, etc.
Answer is D: Systeme Internationale is a unit system based on metre, kilogram and second. There are seven base units and many units are derived from the base. It employs a universal system of prefixes (e.g. milli, mega, pico, etc.) to denote multiples of 10 of the SI units.
23. Which of the following is a base unit within the SI unit system?
A. Second
B. Pascal
C. Joule
D. Kilometre per hour
Answer is A: The second is one of the seven base units in the SI system, the rest are all derived SI units.
24. Which of the following is a derived unit within the SI unit system?
A. Hertz
B. Candela
C. Kelvin
D. Mole
Answer is A: The unit for frequency hertz (Hz) is derived. The others (B, C, D) are SI base units for luminous intensity, temperature and amount of substance, respectively.
25. What is meant by a “scalar” quantity?
A. One that can be measured using a scale.
B. One that is defined by a magnitude.
C. One that needs both a magnitude and a direction to be defined.
D. One that is known exactly without error.
Answer is B: A scalar quantity needs only a magnitude to be defined. Examples are time, mass, speed, volume, and temperature.
26. What is meant by a “vector” quantity?
A. One that can be measured using a scale.
B. One that is defined by a magnitude.
C. One that needs both a magnitude and a direction to be defined.
D. One that is known exactly without error.
Answer is C: A vector quantity requires both a magnitude and a direction to be defined completely. Examples are velocity, displacement, force, acceleration, momentum, and electric field strength.
27. The “Systeme Internationale” (SI) units have a set of standard prefixes. Which of the following list four of them correctly?
A. Micro = 10−6; hecto = 102; kilo = 103; mega = 106
B. Milli = 10−3; centi = 10−1; deka = 101; giga = 109
C. Nano = 10−8; micro = 10−5; deci = 10−1; tera = 109
D. Deci = 10−1; deka = 101; hecto = 102; kilo = 104
Answer is A: Centi = 10−2 (not 10−1); micro = 10−6 (not 10−5); tera = 1012 (not 109); kilo = 103 (not 104).
28. Which of the following is the unit of a base unit in the SI system of units?
A. Kilometre (km)
B. Kilogram (kg)
C. Kilopascal (kPa)
D. Degrees Celsius (°C)
Answer is B: Kilogram (not gram) is the base unit. Metre (not km) is a base unit. Pascal is a derived unit, while kelvin (not degree Celsius), is the base unit of temperature— even though 1 K has the same magnitude as 1 °C.
29. Which of the following is the unit of a derived unit in the SI system of units?
A. Millisecond
B. Gram
C. Metres/second
D. Kelvin
Answer is C: This unit of speed is derived from distance and time. Milliseconds and grams are just multiples of the base units second and kilogram.
30. A healthy human body temperature is 37 °C, what is this temperature converted to kelvin?
A. 37 K
B. −236 K
C. 236 K
D. 300 K
Answer is D: 0 K = −273 °C. To convert Celsius to kelvin, add 273, hence 37 °C + 273 = 300 K.
31. What is the (gauge) pressure in a car tyre at 28 psi (pounds per square inch) when converted to kilopascals?
A. 193 kPa
B. 193,000 kPa
C. 34.8 kPa
D. 4.1 kPa
Answer is A: 1 psi = 6.89 kPa, hence 28 psi in kilopascal is 28 × 6.89 = 193 kPa.
32. How many micrograms are there in 150 mg?
A. 150,000
B. 0.15
C. 0.015
D. 0.00015
Answer is A: There is 1000 mg in a microgram. So 150 mg = 150,000 μg.
33. Which of the following is equivalent to 100 μm?
A. 0.1 m
B. 0.01 m
C. 0.01 mm
D. 0.1 mm
Answer is D: There are 1000 μm in a millimetre. So 100 μm = 0.1 mm.
35. Which of the following is equivalent to 0.01 L?
A. 100.0 mL
B. 0.1 mL
C. 1.0 mL
D. 10.0 mL
Answer is D: There is 1000 mL in 1 L. So 100 mL in 0.1 L and 10 mL in 0.01 L.