Exam: Complete Study Guide with 120
Multiple Choice Q&A, Rationales &
Predicted Paper
,SECTION 1: MEASUREMENTS AND THEIR ERRORS
1. Which of the following is an SI base unit?
A) newton
B) joule
C) mole
D) pascal
Answer: C) mole
Rationale: The mole is one of the seven SI base units. The newton, joule and
pascal are derived units.
2. Which quantity is scalar?
A) force
B) velocity
C) energy
D) acceleration
Answer: C) energy
Rationale: Energy has magnitude only. Force, velocity and acceleration are
vectors.
3. The prefix pico represents
A) 10^9
B) 10^-9
C) 10^12
D) 10^-12
, Answer: D) 10^-12
Rationale: Pico means one trillionth, or 10^-12.
4. An equation is homogeneous if
A) both sides have the same base units
B) both sides have the same numerical value
C) it contains no constants
D) all terms are vectors
Answer: A) both sides have the same base units
Rationale: Homogeneity of units means every term in the equation has the
same base units.
5. Random error can be reduced by
A) calibrating the instrument
B) correcting a zero error
C) taking repeated readings and calculating a mean
D) using a larger unit
Answer: C) taking repeated readings and calculating a mean
Rationale: Random errors vary unpredictably, so averaging repeated
readings reduces their effect.
6. A systematic error
A) affects all readings in the same direction
B) is reduced by taking a mean
C) always makes readings too small
D) is caused by random fluctuations
Answer: A) affects all readings in the same direction
, Rationale: Systematic errors shift all measurements by a consistent amount
or in a consistent direction.
7. A thermometer has a scale marked in 1 °C divisions. The uncertainty in a
single reading is
A) ±0.1 °C
B) ±0.5 °C
C) ±1 °C
D) ±2 °C
Answer: B) ±0.5 °C
Rationale: For an analogue scale, the uncertainty is usually half the smallest
division.
8. A length is measured as 20.0 cm ± 0.1 cm. The percentage uncertainty is
A) 0.05%
B) 0.5%
C) 5%
D) 10%
Answer: B) 0.5%
Rationale: Percentage uncertainty = (0..0) × 100 = 0.5%.
9. When two quantities are multiplied, their percentage uncertainties are
A) added
B) subtracted
C) multiplied
D) ignored