NG2- ngFor create dynamic ID for the angular 2 for loop attribute based

NG2- ngFor create dynamic ID for the angular 2 for loop attribute based
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You have to access label's attribute like this : [attr.for]="'ques-' + i"

and you have a bug in your ngFor, u lack of :

<div *ngFor="let question of questions; let i = index;">
<span [attr.id]="'ques-' + i">question </span>
</div>

Ref:
http://stackoverflow.com/questions/40239028/angular-2-dynamic-for-attribute-in-ngfor