<form onSubmit='return validar(this)'>
<select size="1" name="qu[]">
<option></option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>
<select size="1" name="qu[]">
<option></option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>
<input type='submit'>
</form>
<script>
function validar()
{
qu=document.getElementsByName('qu[]');
for (n=0;n<qu.length;n++)
{
if ( qu[n].selectedIndex==0)
{
alert("seleccione en la pregunta " + (n+1) + " un valor");
qu[n].focus();
return false;
}
}
return true;
}
</script>