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Here are 20 multiple choice questions (MCQs) with answers from serial numbers 81 to 100 for AP DDSC Secondary Grade Teacher (SGT) Science Content MCQs 2025 based on the Class III to VIII syllabus (up to Class X difficulty level) for the topics: Combustion and Fuels, Fibres, Sound, Some Natural Phenomena, Our Universe.

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AP DSC 2025 SGT Science MCQs (81–100)

81. Which of the following is an inexhaustible natural resource?
A) Coal
B) Petroleum
C) Natural gas
D) Sunlight
✅ Answer: D) Sunlight

82. Which fuel is considered the cleanest among the following?
A) Coal
B) Petrol
C) Diesel
D) Natural Gas
✅ Answer: D) Natural Gas

83. The lowest temperature at which a substance catches fire is called:
A) Flash point
B) Melting point
C) Boiling point
D) Ignition temperature
✅ Answer: D) Ignition temperature

84. Which is a product of coal?
A) Kerosene
B) Diesel
C) Coke
D) Petrol
✅ Answer: C) Coke

85. What is the main constituent of LPG?
A) Methane
B) Butane
C) Ethane
D) Propane
✅ Answer: B) Butane

86. Which part of the candle flame is the hottest?
A) Outer zone
B) Middle zone
C) Inner zone
D) Dark zone
✅ Answer: A) Outer zone

87. Which of the following is a natural fibre?
A) Nylon
B) Polyester
C) Cotton
D) Acrylic
✅ Answer: C) Cotton

88. Which is a synthetic fibre?
A) Wool
B) Silk
C) Rayon
D) Cotton
✅ Answer: C) Rayon

89. The plastic that can be remoulded multiple times is called:
A) Thermosetting plastic
B) Thermoplastic
C) Natural plastic
D) Fibre-reinforced plastic
✅ Answer: B) Thermoplastic

90. Which of the following is non-biodegradable?
A) Cotton cloth
B) Paper
C) Plastic bottle
D) Wood
✅ Answer: C) Plastic bottle

91. Sound travels fastest in:
A) Air
B) Vacuum
C) Water
D) Steel
✅ Answer: D) Steel

92. The unit of frequency is:
A) Newton
B) Joule
C) Hertz
D) Decibel
✅ Answer: C) Hertz

93. Which of these is a longitudinal wave?
A) Light
B) Sound
C) X-rays
D) Radio waves
✅ Answer: B) Sound

94. Which part of the ear helps us in hearing sound?
A) Cochlea
B) Pinna
C) Semicircular canals
D) Eardrum
✅ Answer: A) Cochlea

95. Noise pollution is caused by:
A) Moderate music
B) Talking
C) Thunderstorm
D) Unwanted loud sounds
✅ Answer: D) Unwanted loud sounds

96. Lightning occurs due to:
A) Reflection of sunlight
B) Earthquake
C) Transfer of electric charges
D) Movement of tectonic plates
✅ Answer: C) Transfer of electric charges

97. Which instrument is used to detect earthquakes?
A) Barometer
B) Seismograph
C) Thermometer
D) Speedometer
✅ Answer: B) Seismograph

98. The innermost layer of the flame is:
A) Dark zone
B) Luminous zone
C) Non-luminous zone
D) Blue zone
✅ Answer: A) Dark zone

99. Which of these is an artificial satellite?
A) Moon
B) Mars
C) INSAT
D) Sun
✅ Answer: C) INSAT

100. Which star appears stationary in the sky?
A) Sirius
B) Pole star
C) Vega
D) Betelgeuse
✅ Answer: B) Pole star

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