Quiz 1

Which of the following gas samples would have the largest number of molecules at STP?

• 0.10 L NO

• 0.007 L CO_2

• 15.0 L HCl

• 7.0 L Br₂

How many molecules are in 3 mol NO?

• 3.49 x10^-24 molecules

• 3.79x10²⁴ molecules

• 1.26x10²⁴ molecules

• 1.806 x10²⁴ molecules

How many moles of CaBr₂ are in 5.0 grams of CaBr₂?

• 1000 mol

• 0.025 mol

• 4.0 mol

• 0.042 mol

Iron(III) oxide is formed when iron combines with oxygen in the air. How many grams of Fe₂O₃ are formed when 16.7 g of Fe reacts completely with oxygen?

• 12.0 g

• 47.8 g

• 23.9 g

• 95.6 g

The molar volume of a gas at STP occupies ____.

• 0⁰C

• 1 kilopascal

• 22.4 L

• 12 grams

…………..S8 + ………..O2  $\rightarrow$  …………..SO2

• 1,8,8

• 8,8,1

• 8,1,8

• 2,1,2

………AlCl3 + ………….KOH  $\rightarrow$   ………Al(OH)3 + ……….KCl

the numbers that balance this equation are

• 3,1,3,1

• 1,3,1,3

• 3,3,1,1

• 1,1,3,3

Which of the following gases at STP would have the greatest volume?

• 0.200 mole of SO₂

• 1.00 mole of N₂

• 5.00 mole of H₂S

• 4.00 mole of HBr

The molar mass of calcium carbonate is ........ gm

• 50

• 86

• 100

• 200

A chemical formula written over the arrow in a chemical equation signifies

• a by-product.

• the formation of a gas.

• a catalyst for the reaction.

• an impurity.