What makes alkali metal halides sometimes coloured, which are otherwise Colourless?

Write one property of hydrogen which resembles alkali metal atoms and one property which resembles halogen atoms.

A blackish brown coloured solid 'A' when fused with alkali metal hydroxides in presence of air, produces a dark green coloured compound 'B' which on electrolytic oxidation in alkaline medium gives a dark purple coloured compound 'C' Identify A, B and C and write the reactions involved.

What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.

An optically active amide (A)C_5H_(11)NO on acid hydrolysis gives an acid and NH_3 . When (A) is treated with bromide and alkali a compound is obtained which one treatment with nitrous acid gives an optically active alcohol and nitrogen. The alcohol gives positive iodoform test. What is the structure of A and show the reactions involved.

Frenkel defects are not found in alkali metal halides.

Ionic solids, which have anionic vacancies due to metal excess defect, develop colour. Explain with the help of a suitable example.

A dise of metal is melted and make a solid sphere. What will happen to moment of inertia about the axis passing through centre?

Samples of four metals A,B,C and D were taken and added to the following solutions one by one.The results obtained have been tabulated as follows. Use the table above to answer the following questions about metals A,B,C and D. (i)Which is the most reactive metal? (ii)What would you observe if B is added to a solution of copper (II) sulpahate? (iii)Arrange the metals A,B,C and D in the order of decreasing reactivity.

Take a table - tennis ball and make three slits into it. put semicircular fins cut out of a metal sheet into these slits. Pivot the tennis ball on an axle through its centre with a straight metal wire fixed to a rigid support. Now connect a cycle dynamo to this. connect a bulb in series. Direct a jet of water or steam produced in a pressure cooker at the fins. What do you observe ?

What do you mean by breaking stress? The breaking stress for a metal is 7.8xx10^9 Nm^-2.Calculate the maximum length of the wire made of this metal which may be suspended without breaking. The density of the metal =7.8xx10^3 kg m^-3,g=10ms^-\2'.