EXAM YEAR 2012
Q10. A micron is equivalent to how many millimetres?
[SSC – 2012]
A. 0.1 mm
B. 0.01 mm
C. 0.001 mm
D. 0.0001 mm
Answer: C. 0.001 mm
Explanation: Micron is an older name for the micrometre, or 10⁻⁶ metre. A millimetre is 10⁻³ metre, making one micrometre equal to 10⁻³ millimetre, or 0.001 mm. Micrometres are convenient for small biological and manufactured structures.
EXAM YEAR 2011
Q9. The kilowatt-hour is commercially used as a unit of which quantity?
[UPSC NDA-II GAT – 2011]
A. Electrical energy
B. Electric current
C. Electrical resistance
D. Potential difference
Answer: A. Electrical energy
Explanation: A kilowatt-hour is power multiplied by time, so it quantifies electrical energy. One kilowatt used steadily for an hour gives one kilowatt-hour, equivalent to 3.6 MJ. Electric current, resistance and potential difference use amperes, ohms and volts.
EXAM YEAR 2010
Q8. Which of these is the SI unit of electric charge?
[SSC – 2010]
A. Ampere
B. Coulomb
C. Ohm
D. Volt
Answer: B. Coulomb
Explanation: One coulomb is the amount of charge carried by an electric current of one ampere in one second. Ampere therefore measures the rate of charge flow, not total charge. Ohm and volt are units of resistance and potential difference.
EXAM YEAR 2009
Q7. What is the energy equivalent of one kilowatt-hour?
[UPPSC Prelims General Studies – 2009]
A. 3.6 × 10³ J
B. 3.6 × 10⁵ J
C. 3.6 × 10⁶ J
D. 3.6 × 10⁹ J
Answer: C. 3.6 × 10⁶ J
Explanation: One kilowatt equals 1,000 joules per second, and an hour contains 3,600 seconds. Multiplying 1,000 by 3,600 gives 3.6 × 10⁶ joules. This conversion is commonly needed for electricity-consumption and power calculations.
EXAM YEAR 2008
Q6. About how many nanometres correspond to the height of a six-foot-tall person?
[UPSC Civil Services Prelims – 2008]
A. 183 × 10⁶ nm
B. 234 × 10⁶ nm
C. 183 × 10⁷ nm
D. 181 × 10⁷ nm
Answer: C. 183 × 10⁷ nm
Explanation: Six feet is approximately 1.83 metres. Because one metre contains 10⁹ nanometres, the height equals approximately 1.83 × 10⁹ nanometres, or 183 × 10⁷ nm. Converting the decimal scale carefully is crucial.
Q5. Which of the following is used as a unit of atmospheric pressure?
[Chhattisgarh PSC Prelims – 2008]
A. Bar
B. Knot
C. Joule
D. Ohm
Answer: A. Bar
Explanation: The bar is a metric pressure unit equal to exactly 100,000 pascals. Atmospheric pressure is commonly reported in bars or millibars, although the pascal is the SI unit. Knot measures speed, joule energy and ohm electrical resistance.
EXAM YEAR 2006
Q4. Which water-related measurement is expressed in cusecs?
[Uttarakhand PSC Prelims – 2006]
A. Purity of water
B. Depth of water
C. Rate of water flow
D. Total quantity of water
Answer: C. Rate of water flow
Explanation: Cusec abbreviates cubic foot per second and measures volumetric flow rate or discharge. It specifies how much volume crosses a section every second, rather than the total volume present. One cusec is approximately 28.3 litres per second.
EXAM YEAR 2005
Q3. Which of these represents the smallest length?
[UPPSC Prelims – 2005]
A. Micron
B. Nanometre
C. Fermi (femtometre)
D. Millimetre
Answer: C. Fermi (femtometre)
Explanation: A fermi, now called a femtometre, equals 10⁻¹⁵ metre. A nanometre is 10⁻⁹ metre, a micrometre is 10⁻⁶ metre, and a millimetre is 10⁻³ metre. Therefore the fermi is by far the smallest listed length.
Q2. The Dobson unit is used for measurement of which of these?
[Uttarakhand PSC Prelims – 2005]
A. Thickness of Earth
B. Thickness of diamond
C. Atmospheric ozone column
D. Noise level
Answer: C. Atmospheric ozone column
Explanation: Dobson units describe the total ozone content above a location, expressed as an equivalent compressed layer thickness. A value of 100 DU corresponds to one millimetre of pure ozone at standard conditions. Noise levels are commonly expressed in decibels.
EXAM YEAR 2002
Q1. A pressure of 1 kilogram-force per square centimetre is approximately equal to how many bars?
[Uttarakhand PSC Prelims – 2002]
A. 0.1 bar
B. 1.0 bar
C. 10.0 bar
D. 100.0 bar
Answer: B. 1.0 bar
Explanation: One kilogram-force per square centimetre corresponds to about 98,066.5 pascals. Since one bar is exactly 100,000 pascals, the pressure is approximately 0.981 bar, making 1.0 bar the nearest option. Kilogram-force is a force, unlike kilogram of mass.
