BOOTSTRAP Looping checkbox

i have problem looping checkbox bootstrap from result_array() this the pics 1 and this the code

<?php if ($bn) : ?>
<div class="row">
    <?php foreach ($bn as $a) : ?>
    <div class="col">
        <div class="form-check">
            <input class="form-check-input" type="checkbox" value="1" id="1" name="1" checked>
            <label class="form-check-label" for="1">Data</label>
        </div>
    </div>
    <?php endforeach; ?>
</div>
<?php endif; ?>

my data in database 5 record

how to get data like that result_array() be like 2

I mean if looping has been done 4 times. make a new row. so each row is filled with 4 columns