Which of the following is not a compound? Sulfur, sodium chloride, ammonia, carbon dioxide

Find the mass in grams of hydrogen gas produced when 14.0 moles of hcl is added to an excess amount of magnesium.

The diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

What diagram shows the ionic compound of magnesium oxide