Answer is: coefficient is one.
Chemical reaction: SiO₂ + 4HF → SiF₄ + 2H₂O.
Reaction is balanced when there are equal numbers of elements in both side of the chemical reaction.
HF - hydrofluoric acid, <span>highly corrosive, dissolves many materials.</span>
SiF₄ - silicon tetrafluoride.
<span>The molten material then spreads out, pushing the older rock to both sides of the ridge. As the molten material cools, it forms a strip of solid rock in the center of the ridge. Then more molten material flows into the crack. The material splits apart the strip of solid rock that formed before, pushing it aside. Hope this helps! (:</span>
C - rising and cooling, causing water vapor to condense