3 Calculate the work done against external atmospheric pressure when 1 g of water changes to
1672cm3
of steam. Take the atmospheric pressure as
1.013×105Nm−2
169.3 J
342.4 J
226.2 J
143.5 J
4 An electric kettle contains 1.5 kg of water at
100oC
and powered by a 2.0 kW electric element. If the thermostat of the kettle fails to operate, approximately how long will it take for the kettle boil dry? (Take the specific latent heat of vaporization of water as
2000kJkg−1)
500s
1000s
1500s
3000s
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