first assume that A+B+C=pi,then use tana

+tanb+tanc=tana*tanb*tanc

then use a.m g.m inequality to get the answer.

I did read in a book that when two bodies are rubbed together one of them loses elect. and gets +vely charged and other -vely charged .but why does a body having less work function has to lose elect.while rubbing and one with higher w gain elect. please explain !

refer page no. 465 RCM ,degree of dissociation from vapour density.

i advice you to first go through the theory and then jump to solving problems.concepts are more important than problems.

best of luck for IIT-JEE 2008 !

electronic conf. of cs + is (2,8,18,18,8) .it has 5 atomic shells.so.the effective nuclear charge on each electron is less.the screening effect is less ,so the size is less.whereas in cl minus ,it has 3shells ,so the effective nuclear charge on each electron is more.but the size of it is greater due to the inter-electronic repulsion in the atom .so the size of ci minus is greater than cs+.

i can give you another example of inter -electronic repul.check out the atomic sizes of cl &Ar.according to the atomic size theory ,size of Ar  should be more than cl coz' of less electrons in cl.compare these two cases and you will get the concept.i don't expect you to rate me.