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Question
Fill in the blanks using suitable words.
(a) A thick glass tumbler is taken. Boiling hot water is poured into it. The hot water is in contact with the ______________ layer of glass. By ______________ this layer becomes hot and _____________. Glass is a ______________conductor of heat. Thus the _______________ layer does not get heated quickly. It does not ________________ as much. This ______________ expansion of the layers causes the glass to crack.
(b) Burning coal is kept on a muslin cloth which is spread out on a copper plate. Copper is a ______________ conductor of ______________. It takes away the heat from the ______________. The ______________ of the muslin cloth does not rise enough for it to catch fire.
(c) Rajesh opened a gas tap on the kitchen range. he held a piece of wire netting above it and struck a match below the wire netting. He found the gas burnt below the wire netting but not aove it. the wire netting is made of _______________ which is a good ______________ of heat. It takes away the heat from the fire. Thus the _____________ above the netting did not catch fire.
(a) A thick glass tumbler is taken. Boiling hot water is poured into it. The hot water is in contact with the ______________ layer of glass. By ______________ this layer becomes hot and _____________. Glass is a ______________conductor of heat. Thus the _______________ layer does not get heated quickly. It does not ________________ as much. This ______________ expansion of the layers causes the glass to crack.
(b) Burning coal is kept on a muslin cloth which is spread out on a copper plate. Copper is a ______________ conductor of ______________. It takes away the heat from the ______________. The ______________ of the muslin cloth does not rise enough for it to catch fire.
(c) Rajesh opened a gas tap on the kitchen range. he held a piece of wire netting above it and struck a match below the wire netting. He found the gas burnt below the wire netting but not aove it. the wire netting is made of _______________ which is a good ______________ of heat. It takes away the heat from the fire. Thus the _____________ above the netting did not catch fire.
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Solution
(a) A thick glass tumbler is taken. Boiling hot water is poured into it. The hot water is in contact with the inner layer of glass. By heating, this layer becomes hot and expand. Glass is a bad conductor of heat. Thus the outer layer does not get heated quickly. It does not expand as much. This different expansion of the layers causes the glass to crack.
(b) Burning coal is kept on a muslin cloth that is spread on a copper plate. Copper is a good conductor of heat. It takes away the heat from the muslin cloth. The temperature of the muslin cloth does not rise enough for it to catch fire.
(c) Rajesh opened a gas tap on the kitchen range. He held a piece of wire netting above it and struck a match below the wire netting. He found the gas burnt below the wire netting but not above it. The wire netting is made of galvanised iron, which is a good conductor of heat. It takes away the heat from the fire. Thus the air above the netting did not catch fire.
(b) Burning coal is kept on a muslin cloth that is spread on a copper plate. Copper is a good conductor of heat. It takes away the heat from the muslin cloth. The temperature of the muslin cloth does not rise enough for it to catch fire.
(c) Rajesh opened a gas tap on the kitchen range. He held a piece of wire netting above it and struck a match below the wire netting. He found the gas burnt below the wire netting but not above it. The wire netting is made of galvanised iron, which is a good conductor of heat. It takes away the heat from the fire. Thus the air above the netting did not catch fire.
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