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A electric kettle ( rated accurately at `2.5 kW`) is used to heat `3 kg` of water from `15^(@)C` to boiling point . It takes `9.5 min`. Then the amount of heat that has been lost isA. `3.5 xx 10^(5) J`B. `7 xx 10^(8) J`C. `3.5 xx 10^(4) J`D. `7 xx 10^(8) J` |
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Answer» Correct Answer - A Energy consumed in `9.5 min ` is `2.5 xx 1000 xx 9.5 xx 60 J = 1425000 J` Heat usefully consumed is ` 3 xx 4.2 xx 1000 xx (100 - 15 ) J = 1071000 J` Loss `= 3.54 xx 10^(5) J` |
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