Question 1

A recipe calls for 90 apples. If one dozen apples has a mass of 2.0 kg, what is the total mass of apples required for the recipe?

Accepted Answer

$$15\ 	ext{kg}$$

Question 2

If 0.20 bushel of apples is equivalent to one dozen apples, and the mass of one dozen apples is 2.0 kg, what is the mass of 0.50 bushel of apples?

Accepted Answer

$$5.0\ 	ext{kg}$$

Question 3

An apple contains 8 seeds and has a mass of $$0.2\ 	ext{kg}. $$How many apple seeds are present in $$14\ 	ext{kg} of $$apples?

Accepted Answer

$$560\ 	ext{seeds}$$

Question 4

A case of paper has a mass of $$2000\ 	ext{g}$$ and contains $$10$$ reams, each with $$500$$ sheets. What is the mass, in grams, of $$50$$ sheets of paper?

Accepted Answer

$$100\ 	ext{g}$$

Question 5

What is the mass ratio of $$10$$ carbon atoms to $$10$$ hydrogen atoms?

Accepted Answer

$$12:1$$

Question 6

If you have $$36.0\ 	ext{kg} of $$carbon atoms and $$3.0\ 	ext{kg} of $$hydrogen atoms, do they contain the same number of atoms?

Accepted Answer

No, because carbon atoms are heavier than hydrogen atoms.

Question 7

Calculate the molar mass of hydrazine ($$	ext{N}_2	ext{H}_4).$$

Accepted Answer

$$32.0\ 	ext{g/mol}$$

Question 8

What is the molar mass of calcium chloride ($$	ext{CaCl}_2$$)?

Accepted Answer

$$110.98\ 	ext{g/mol}$$

Question 9

What is the mass, in grams, of $$0.250$$ mol of potassium carbonate ($$	ext{K}_2	ext{CO}_3$$)?

Accepted Answer

$$34.6\ 	ext{g}$$

Question 10

How many moles are in $$20.0\ 	ext{g} of $$sulfur tetroxide ($$	ext{SO}_4$$)? (Molar mass $$\approx 96.1\ 	ext{g/mol})$$

Accepted Answer

$$0.208\ 	ext{mol}$$

Question 11

A $$10.0\ 	ext{g}$$ sample of a compound made of aluminum and selenium contains $$8.0\ 	ext{g} of $$selenium. What is the percent composition of selenium in the compound?

Accepted Answer

$$80.0\%$$

Question 12

What is the percent by mass of zinc in zinc carbonate ($$	ext{ZnCO}_3$$)? (Molar mass $$= 65.4 + 12.0 + 48.0 = 125.4\ 	ext{g/mol})$$

Accepted Answer

$$52.2\%$$

Question 13

Which nitrogen compound has the largest percent by mass of nitrogen?

Accepted Answer

$$	ext{N}_2	ext{O}$$

Question 14

A sample of allicin ($$	ext{C}_6	ext{H}_{10}	ext{S}_2	ext{O}) $$contains $$3.0 	imes 10$$^{21}$$ atoms of carbon. How many hydrogen atoms does this sample contain?

Accepted Answer

$$5.0 	imes 10$$^{21}$$

Question 15

A sample of calcium carbonate ($$	ext{CaCO}_3) $$contains $$1.4 	imes 10$$^{19}$$ atoms of carbon. How many oxygen atoms does this sample contain?

Accepted Answer

$$4.2 	imes 10$$^{19}$$

Question 16

A sample of ammonium nitrate ($$	ext{NH}_4	ext{NO}_3) $$contains $$4.0 	imes 10$$^{25}$$ atoms of nitrogen. How many hydrogen atoms does this sample contain?

Accepted Answer

$$8.0 	imes 10$$^{25}$$

Question 17

Table sugar (sucrose) has the formula $$	ext{C}_{12}	ext{H}_{22}	ext{O}_{11}. $$What is its molar mass?

Accepted Answer

$$342\ 	ext{g/mol}$$

Question 18

A $$40.0\ 	ext{g}$$ sample of ore contains $$18.0\ 	ext{g} of $$iron and the rest is oxygen. What is the percent composition of iron in the sample?

Accepted Answer

$$45.0\%$$

Question 19

Which compound has the greatest ratio of nitrogen to oxygen?

Accepted Answer

$$	ext{N}_2	ext{O}$$

Introductory Chemistry: Mass, Moles, Percent Composition, and Atomic Ratios Practice

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