Thanks for all your replies

Jim sorry got giving more details.
I have tried my best to answer few of your questions.

"Mics can cost a few bucks or a few thousand bucks so it might help "
In an range of $150 - $200

"exact purpose and application the mic will be used for. "
For singing as well as for recording.

"I take it that it is a live performance? "
Yes it is a live performance

"How is it being recorded?"
I guess she had a recorder that had a inbuild mic in it.

"What external noises are we talking about? "
The performance was in a open audithorium.So like people applause,talking , childrens crying everything got recorded.

"Does she want the orchestra recorded seperately or on the same mic? "
No she want the orchestra recorded along with her voice.

I recently went to a musical shop. The person over there recommended to have separate mic for vocal and instruments and give these mic output to the mixer.Then give the mixer's output to the recorder. Just like wat Daklander recommended.

Thanks & Regards
Ramya