A) vacuum |
B) air |
C) water |
D) steel |
D) steel |
1). Sounds cannot travel through
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2). The speed of sound will be highest in
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3). Thunder is heard much after a flash of lightning is seen because
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4). Mach number is used in connection with the speed of
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5). Echoes are produced due to
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6). A clearly separate echo of a sound is heard when the minimum distance of the4 reflecting surface from the source of sound is
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7). The walls and ceiling of an auditorium are covered with fibrous material, such as glass fibre, to
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8). Bats can fly in the dark because
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9). A police van sounding its siren is moving away from an observer. The pith (shrillness) of the sound from the siren relative to its normal pitch is
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10). A device used for measuring the depth of the sea is called
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