While loop with bootstrap [closed]

Try using the count variable to increment the loop.

<div class="panel-group" id="accordion" role="tablist" aria-multiselectable="true">
    <?php if(get_field('faq_general_ht')): ?>
           <?php $count=0; ?>
            <?php while(has_sub_field('faq_general_ht')): ?>
                <div class="panel panel-default">
                  <div class="panel-heading" role="tab" id="headingTwo">
                      <h4 class="panel-title">
                       <?php echo '<a data-toggle="collapse" data-parent="#accordion" href="#collapse' .$count. '"aria-expanded="true">' ?>
                         <p><?php the_sub_field('faq_general_question_ht') ?></p>
                        </a>
                      </h4>
                    </div>
                    <?php echo '<div id="collapse' .$count. '" class="panel-collapse collapse" role="tabpanel">' ?>
                      <div class="panel-body">
                         <p><?php the_sub_field('faq_general_answer_ht') ?></p>
                      </div>
                    </div>
                  </div>
             <?php $count++; ?>
        <?php endwhile; ?>
    <?php endif; ?>
</div>