Try this code:
<select name="wgtmsr" id="wgtmsr">
<option value="kg">Kg</option>
<option value="gm">Gm</option>
<option value="pound">Pound</option>
<option value="MetricTon">Metric ton</option>
<option value="litre">Litre</option>
<option value="ounce">Ounce</option>
</select>
CSS:
#wgtmsr{
width:150px;
}
If you want to change the width of the option you can do this in your css:
#wgtmsr option{
width:150px;
}
Maybe you have a conflict in your css rules that override the width of your select