(i) What mass of ice at 0°C added to 2.1 kg water, will cool it down from 75°C to 25°C ? Given Specific heat capacity of water = 4.2 Jg^-1 °C^-1, Specific latent heat of ice = 336 Jg^-1.

(ii) The diagram below shows a cooling curve for a substance:
(a) State the temperatures at which the substance condenses.
(b) The temperature range in which the substance is in liquid state.

(c) Why do we prefer ice to ice-cold water for cooling a drink?

(iii) The diagram below shows a cardboard on which iron filings are kept. A wire bent in the form of a loop is seen passing through the cardboard. When current flows through it the iron filings arrange themselves as shown below with the direction of magnetic field.

(a) State the polarities of the battery at A and B.
(b) State the effect on the magnetic field if an iron rod is held along the axis of the coil.
(c) State one way to:
1. change the polarity of the coil.
2. decrease the strength of the magnetic field around the coil.

Solution

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