presence of quorum

Yes necessary to pass resolution.

but it is not provided in the act,
is it an amendment or the rules prescribes the same or is it secretarial standards??

It's not any amendment or not any Ss has prescribed this

Exemption to private companies.

But act provides only for the presence of the quorum within half an hour ,
further a book by 'Munish Bhandari' states that the quorum need not to b present at passing every resolution
then why quorum shall be present

Quorum is not necessary at adjourned meeting.

If all members but less than quorum present at meeting:--- If the numbers of members of the company is reduced below minimum required quorum for the meeting, than all those who are members, can personally attend the meeting and question of quorum will not arise However ,there are other exceptions regarding quorum.

  Ankit Kumar     29 November 2017is it necessary for the quorum to be present at the time of passing each & every resolution??

The quorum should be present for all the business.
for eg,in a meeting 4 business were to be discussed. When meeting started quorum was present.3 business were discussed & resolutions were passed.
but before beginning of 4th business some members leave the meeting that quorum was not available. Now in this case the business can't be transacted.

Further the quorum should be present at the time when the meeting begins to transact the business but it need not be present throughout or at the time of taking the vote on any resolution.

thank u very much.