Explanation:
<em><u>2Al + 2NaOH + 6H2O → 2Na[Al(OH)4] + 3H2</u></em>
<em><u></u></em>
Gravity slows it down dramatically so that is why it slows down
Release of heat, color change, or produce of bubbles create are chemical changes that create sound.
Oxygen and selenium both have 6 valence electrons. They're in the same group hope this helps