Q61. The composition of gases in
exosphere is
NDA 2021 (I)
A helium and hydrogen B neon and oxygen C neon and hydrogen D helium and neon
Show answer
Correct answer: helium and hydrogen
Q62. Which one of the following is the
chemical formula of hypobromous
acid?
NDA 2021 (I)
A HBrO4 B HOBr C HBr D HBrO3
Show answer
Correct answer: HOBr
Q63. The statement “friction force is a
contact force while magnetic force is a
non-contact force” is
NDA 2021 (I)
A always true B true only at 0°C C a false statement D Either true or false depending upon
the temperature of the surroundings
Show answer
Correct answer: always true
Q64. Which of the following pairs of
physical phenomena and the
discoverer is/are correctly matched?
NDA 2021 (I)
1.
James Chadwick :
Photoelectric
effect
2.
Albert Einstein :
Neutron
3.
Marie Curie :
Radium
Select the correct answer using the
codes given below.
A 1, 2 and 3 B 1 and 2 C 2 and 3 D Only 3
Show answer
Correct answer: Only 3
Q65. Which one of the following regarding
density of water at atmospheric
pressure is correct?
NDA 2021 (I)
A Density of water at 4°C is 1000 kg/m3
. B Density of water at 0°C is 1000 kg/m3 C Density of water at 0°C is 100 kg/m3 D Density of water at 4°C is 10 kg/m3.
Show answer
Correct answer: Density of water at 4°C is 1000 kg/m3
.
Q66. Solder used for joining metal parts
together is an alloy of
WBCS 2021
A Fe and Cu B Fe and Zn C Sn and Cu D Sn and Pb
Show answer
Correct answer: Sn and Pb
Q67. The freezing chest in refrigerator is
kept near the top because WBCS 2021
A it is convenient to use. B it reduces cost. C it cools the remaining space by the
process of conduction. D convection currents are set up.
Show answer
Correct answer: convection currents are set up.
Q68. Dry ice means
WBCS 2021
A Ice at −
°
23 C B Ice at 4°C C Solid SO2 D Solid CO2
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Correct answer: Solid CO2
Q69. Pure silicon at 0 K is
WBCS 2021
A semiconductor B metal C insulator D superconductor
Show answer
Correct answer: insulator
Q70. With reference to the radioactivity,
which of the following statements
is/are correct?
1. Radioactivity is a nuclear property.
2. Hydrogen bomb is prepared on the
principle of nuclear fission.
Select the correct answer using the
codes given below.
UPPSC 2021
A Only 1 B Only 2 C Both 1 and 2 D Neither 1 nor 2
Show answer
Correct answer: Only 1
Q71. Which one of the following is the main
constituent of LPG?
UPPSC 2021
A Hexane B Pentane C Butane D Methane
Show answer
Correct answer: Butane
Q72. Bee sting causes, severe pain and
burning sensation due to the presence
of
OPSC 2021
A Acetic acid B Sulfuric acid C Citric acid D Methanoic acid
Show answer
Correct answer: Methanoic acid
Q73. Which is NOT a synthetic polymer?
OPSC 2021
A PVC B Nylon C Polystyrene D Resin
Show answer
Correct answer: Resin
Q74. Which of the following does not belong
to natural air pollutant?
OPSC 2021
A Hydrocarbon B SOx C NOx D Peroxyacetyl nitrate
Show answer
Correct answer: Peroxyacetyl nitrate
Q75. When a white light beam is made to
fall on a hollow prism filled with water,
it breaks into seven constituent
colours. Which of the following colours
suffer the maximum angle of
deviation?
Asst. Commandant 2021
A Red B Violet C Green D All suffer by equal amount of
deviation
Chemistry
Show answer
Correct answer: Violet
Q76. An object is placed 10 cm in front of a
lens. The image formed is real,
inverted and of same size as the
object. What is the focal length and
nature of the lens?
Asst. Commandant 2021 P-I
A 5 cm, converging B 10 cm, diverging C 20 cm, converging D 20 cm, diverging
Show answer
Correct answer: 5 cm, converging
Q77. Which electromagnetic radiation(s)
is/are used to cook food?
Asst. Commandant 2021 P-I
A Infrared radiation only B Microwave radiation only C Infrared and microwave radiations D All electromagnetic radiations
Show answer
Correct answer: Microwave radiation only
Q78. What is the approximate wavelength
of violet light in air?
Asst. Commandant 2021 P-I
A 0.7 µm B 0.6 µm C 0.5 µm D 0.4 µm
Show answer
Correct answer: 0.4 µm
Q79. An electric bulb is connected to a 110
V generator. The current is 0.2 A.
What is the power of the bulb?
CDS 2021 (II)
A 0.22 W B 2.2 W C 22 W D 220 W
Show answer
Correct answer: 22 W
Q80. The magnetic field lines inside a
current carrying long solenoid are in
the form of
CDS 2021 (II)
A ellipse B parabola C hyperbola D parallel straight lines
Show answer
Correct answer: parallel straight lines