Units and Measurements Practice Questions
20 free Units and Measurements practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following is the SI base unit of length?
- A Centimeter
- B Meter
- C Kilometer
- D Inch
Correct answer: Meter
The meter is the SI base unit of length. It is defined in terms of the speed of light in vacuum. Other units like centimeter and kilometer are derived from the meter.
What is the SI unit of mass?
- A Gram
- B Kilogram
- C Newton
- D Pound
Correct answer: Kilogram
The kilogram is the SI base unit of mass. It is defined using the Planck constant. The gram is a submultiple of the kilogram.
Which physical quantity is measured in seconds (s)?
- A Length
- B Time
- C Temperature
- D Current
Correct answer: Time
The second is the SI base unit of time. It is defined based on the vibrations of cesium atoms. Time measurement is fundamental in physics.
The SI unit of electric current is:
- A Volt
- B Ohm
- C Ampere
- D Watt
Correct answer: Ampere
The ampere is the SI base unit of electric current. It measures the flow of electric charge per second. Other units like volt and ohm are derived units.
Which of the following is a derived SI unit?
- A Meter
- B Kilogram
- C Newton
- D Second
Correct answer: Newton
The newton is a derived SI unit used to measure force. It is defined as kg·m/s². It is derived from base units of mass, length, and time.
What is the SI unit of temperature?
- A Celsius
- B Kelvin
- C Fahrenheit
- D Joule
Correct answer: Kelvin
The kelvin is the SI base unit of thermodynamic temperature. It is defined using the Boltzmann constant. Celsius is a commonly used scale but not the SI base unit.
Which instrument is commonly used to measure mass in a laboratory?
- A Thermometer
- B Timer
- C Balance
- D Voltmeter
Correct answer: Balance
A balance is used to measure mass by comparing an object to known standards. It provides accurate measurements in laboratories. Thermometers and voltmeters measure different quantities.
The SI unit of force is equivalent to:
- A kg·m/s
- B kg·m/s²
- C kg/s²
- D m/s²
Correct answer: kg·m/s²
Force in SI units is measured in newtons, which equals kg·m/s². This comes from Newton's second law, F = ma. It combines mass and acceleration units.
Which of the following quantities is dimensionless?
- A Velocity
- B Linear acceleration
- C Refractive index
- D Force
Correct answer: Refractive index
The refractive index is a ratio of two similar quantities and has no units. Therefore, it is dimensionless. Other options involve measurable physical dimensions.
The SI unit of energy is:
- A Watt
- B Joule
- C Newton
- D Pascal
Correct answer: Joule
The joule is the SI unit of energy. It is defined as the work done when a force of one newton moves an object one meter. Watt measures power, not energy.
What is the SI unit of pressure?
- A Bar
- B Pascal
- C Atmosphere
- D Newton
Correct answer: Pascal
The pascal is the SI unit of pressure. It is defined as one newton per square meter. Other units like bar and atmosphere are non-SI units.
Which prefix represents a factor of 10^-3?
- A Kilo
- B Milli
- C Mega
- D Micro
Correct answer: Milli
The prefix 'milli' represents 10^-3. It means one-thousandth of a unit. For example, one millimeter is 0.001 meters.
The SI unit of power is:
- A Joule
- B Watt
- C Volt
- D Ampere
Correct answer: Watt
The watt is the SI unit of power. It measures the rate of energy transfer, equal to one joule per second. Power describes how fast work is done.
Which quantity is measured in meters per second (m/s)?
- A Acceleration
- B Velocity
- C Force
- D Energy
Correct answer: Velocity
Velocity is measured in meters per second. It represents the rate of change of displacement with time. Acceleration is measured in m/s².
Which base quantity is measured in moles?
- A Amount of substance
- B Mass
- C Length
- D Luminous intensity
Correct answer: Amount of substance
The mole is the SI base unit for amount of substance. It represents a specific number of elementary entities. It is fundamental in chemistry and physics.
What is the SI unit of frequency?
- A Hertz
- B Joule
- C Newton
- D Tesla
Correct answer: Hertz
The hertz (Hz) is the SI unit of frequency. It represents one cycle per second. Frequency describes how often a repeating event occurs.
Which instrument is used to measure electric potential difference?
- A Ammeter
- B Voltmeter
- C Galvanometer
- D Barometer
Correct answer: Voltmeter
A voltmeter measures electric potential difference between two points. It is connected in parallel in a circuit. The unit of potential difference is the volt.
The SI unit of luminous intensity is:
- A Lux
- B Candela
- C Lumen
- D Watt
Correct answer: Candela
Candela is the SI base unit of luminous intensity. It measures the perceived power of light in a particular direction. Lux and lumen are related but derived units.
If a quantity has the dimensions ML^2T^-2, it represents:
- A Force
- B Power
- C Energy
- D Pressure
Correct answer: Energy
The dimensional formula ML^2T^-2 corresponds to energy or work. It is derived from force multiplied by distance. This matches the unit joule.
Which of the following conversions is correct?
- A 1 km = 100 m
- B 1 m = 1000 mm
- C 1 g = 100 kg
- D 1 s = 100 min
Correct answer: 1 m = 1000 mm
One meter equals 1000 millimeters. The prefix 'milli' represents one-thousandth of a meter. The other options provide incorrect conversions.