The diagram alongside shows three resistors connected across a cell of e.m.f. 1.8 V and internal resistance r. Calculate:

(i) Current through 3 Ω resistor.

(ii) The internal resistance r.

(i) What are superconductors?

(ii) Calculate the current drawn by an appliance rated 110 W, 220 V when connected across 220 V supply.

(iii) Name a substance whose resistance decreases with the increase in temperature.

A piece of ice of mass 60 g is dropped into 140 g of water at 50 °C. Calculate the final temperature of water when all the ice has melted. (Assume no heat is lost to the surrounding).
Specific heat capacity of water (c) = 4.2 Jg^-1k^-1,
Specific latent heat of fusion of ice (L) = 336 Jg^-1

The diagram below shows the change of phases of a substance on a temperature vs time graph on heating the substance at a constant rate.

(i) Why is the slope of CD less than slope of AB?

(ii) What is the boiling and melting point of the substance?