A sphere of ice at 0^(@)C having initial radius R is placed in an environment having ambient temperature gt 0^(@)C . The ice melts uniformly, such that shape remains spherical. After a time 't' the radius of the sphere has reduced to r. which graph best depicts r(t)

Ice starts forming in lake with water at 0^(@)C and when the atmospheric temperature is -10^(@)C . If the time taken for 1 cm of ice be 7 hours. Find the time taken for the thickness of ice to change from 1 cm to 2 cm

A certain amount of ice is supplied heat at a constant rate for 7 min. For the first one minute the temperature rises uniformly with time. Then it remains constant for the next 4 min and again the temperature rises at uniform rate for the last 2 min. Given S_("ice")=0.5cal//g^(@)C,L_(f)=80cal//g . The initial temperature of ice is

A certain amount of ice is supplied heat at a constant rate for 7 min. For the first one minute the temperature rises uniformly with time. Then it remains constant for the next 4 min and again the temperature rises at uniform rate for the last 2 min. Given S_("ice")=0.5cal//g^(@)C,L_(f)=80cal//g . Final temperature at the end of 7 min is

An ice box used for keeping eatables cool has a total wall area of 1m^2 and a wall thichness of 5.0 cm. The thermal cunductivity of the ice box is K=0.01 J//m^@C . It is filled with large amount of ice at 0^@C along with eatables on a dfay when the temperature is 30^@C The latent heat of fusion of ice is 334xx10^3 J//kg . The amount of ice melted in one day is ( 1 day =86,000s )

An electric toaster uses nichrome for its heating element. When a negligibly small current passes through it, its resistance at room temperature (27.0^(@)C) is found to be 75.3 Omega . When the toaster is connected to a 230 V supply, the current settles, after a few seconds, to a steady value of 2.68 A. What is the steady temperature of the nichrome element ? The temperature coefficient of resistance of nichrome averaged over the temperature range involved , is 1.70 xx 10^(-4) ""^(@) C^(-1) .

An electric toaster uses nichrome for its heating element. When a negllgibly small current pases through it, its resistance at room temperature (27.0^(@)C) is found to be 75.3 Omega. When the toaster is connected to a 230 V supply, the current settles, after a few seconds, to a steady value of 2.68A. What is the steady temperature of the nichrome element ? The temperature coefficient of resistance of nichrome averaged over the temperature range involved is 1.70 xx 10 ^(-4)"" ^(@)C ^(-1).

Surafce tension is exhibited by liquids due to force of attraction between the molecules of the liquid .The surface tension decreases with increases in temperature and vanishes at boiling point Given that the latent heat of vaporization for water L_(v)=540(kcal)/(kg) the mechanical equivalent of heat J=4.2(J)/(cal) density of water rho_(w)=10^(3)kgl^(-1) ,Avogadro'sno. N_(A)=6.0xx10^(26)k " mole"^(-1) . Molecular weight of water M_(A)=10kg , for 1k mole . (a) Estimate the energy required for one molecule of water to evaporated. (b) Show that the inter molecular distance for water is d=((M_(A))/(N_(A))xx(1)/(rho_(w)))^((1)/(3)) and find its value. (c ) 1 g of water in the vapour state at 1 atm occupies 1601cm^(3) , estimate the intermolecular distance at boiling point in the vapour state. (d) During vaporisation a molecule overcomes a force F, assumed constant to go from an inter molecular distance d to d .Estimate the value of F. (e ) Caculate (F)/(d) , which is a measure of the surface tension.

The temperature time graph given below shows the heating curve for pure wax. From the graph answer the following questions: a. What is the physical state of wax at the points A,B,C,D? b.What is the melting point of wax? c. What is its boiling point? d. Which portions of the graph indicate that change of state is taking place? e. Name the terms used for heat absorbed during the change of slates involved in above process.

Answer the following questions based on the P - T phase diagram of CO_(2) : (a) CO_(2) at 1 atm pressure and temperature -60^(@)C is compressed isothermally. Does it go through a liquid phase ? (b) What happens when CO_(2) at 4 atm pressure is cooled from room temperature at constant pressure ? (c) Describe qualitatively the changes in a given mass of solid CO_(2) at 10 atm pressure and temperature -65^(@)C as it is heated up to room temperature at constant pressure. (d) CO_(2) is heated to a temperature 70^(@)C and compressed isothermally. What changes in its properties do you expect to observe ?