8. a volume of 7.5 l of hydrogen gas at stp was produced from the single-replacement
reaction of zinc with nitric acid. calculate the mass of zinc needed for this reaction.

20.60 g

We are given;

Required to determine the mass of zinc needed for the reaction.

Zn(s) + 2HNO₃(aq) → Zn(NOₐ)₂ + H₂(g)

we know that 1 mole of a gas occupies 22.4 L at STP

Moles of Hydrogen = 7.05 L ÷ 22.4 L/mol

                                 = 0.315 moles

Then, we determine the number of moles of Zinc that reacted

Therefore,

Moles of Zinc = Moles of Hydrogen

Hence;

Mass of Zinc = 0.315 moles × 65.38 g/mol

                     = 20.60 g

Thus, the mass of zinc that reacted 20.60 g

a rain shadow is a dry region of land on the side that is protected against the prevailing winds of a mountain range. the prevailing winds are the winds that occur most of the time in a particular place of the earth

prevailing winds carry air toward the mountain range. as the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. on this side of the mountains, called the windward side, precipitation falls in the form of  rain  or snow. this dry air produces a  rain shadow.