ICSE − Q & A

Can anyone send the correct format of formal n informal letter of hindi? 
One more question, is it necessary to make envelope with tat

My hindi teacher said this and whole school is following.
She said u student of all batches of 10th that u don't need to learn ekanki sanchai(ES) but u have to do whole of Sahitya sagar(SS).As we know SS have story n poem n ES have play.so total according to her 3 books.If we do this we are doing under ICSE criteria.So have u been also told same in school.

How long do you"ll take to read whole naya raasta book?

Anyone doing poems or I m the only person?

Guys i have seen question in prelim papers for mahabharat chap which are not mentioned in ekanki but has a backstory....like how was shishupal killed and all...so do we have to know certain stories?

I have a list of essays which I have come across after questioning various teachers of renowed schools bet me any one of these topics will come 
Nari(girl) beti padhao beti bachao
Terrorism
Olympics
Swachtha Abhiyan
Demonetisation
Water scarcity

Guys is studying this much enough-
1.Pariaivachi
2.Vilom
3.Bhavvachak
4.Visheshan

For biology, is Selina's book enough??

chemistry exam tips please...!

What's the difference between 'hain' and 'hai' (I mean the one with and the one without a dot) Also when and where to use it in a sentence?