<form [formGroup]="form">
        <input *ngFor="let answer of question.answers; let i = index; trackBy: trackByFn" 
                type="checkbox" 
                formControlName="answer[{{i}}]"
                (change)="answer.selected = !answer.selected">

</form>
<form [formGroup]="form">
  <ul>
    <li *ngFor="let answer of question.answers; let i = index; trackBy: trackByFn">
      <input type="checkbox"  formControlName="answer[{{i}}]" (change)="answer.selected = !answer.selected"> {{answer.content}}
    </li>
  </ul>
</form>
Update template of true-false question ...
Update template of true-false question ...
