Unit Test — Unit test Answers

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A year has 365 days, and a day has 24 hours. If an hour has 60 minutes and a minute has 60 seconds, how many seconds are there in 1 year?

54,750 s

525,600 s

3.15 107 s

1.89 109 s

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The following balanced equation shows the formation of ammonia.N2 + 3H2 2NH3How many moles of nitrogen are needed to completely convert 6.34 mol of hydrogen?

1.02 mol

2.11 mol

12.68 mol

19.02 mol

What is the molar mass of fluorine, F2?

9.00 g/mol

18.00 g/mol

19.00 g/mol

38.00 g/mol

The equation below shows lithium reacting with nitrogen to produce lithium nitride.6Li + N2 2Li3NIf 12 mol of lithium were reacted with excess nitrogen gas, how many moles of lithium nitride would be produced?

4.0 mol

6.0 mol

12 mol

36 mol

A teacher wants to figure out the amount of a solution that is needed for a titration experiment in a class lab. The class has 15 students, and each experiment needs 50 mL of solution. If each student will perform the experiment two times, how many mL of solution will the teacher need for the whole class?

375 mL

750 mL

1500 mL

3000 mL

Avogadro’s number was calculated by determining the number of atoms in

12.00 g of carbon-12.

14.00 g of carbon-12.

12.00 g of oxygen.

14.00 g of oxygen.

How would you write 16,340 in scientific notation with 2 significant figures?

16,300

1.63 x 104

16,000

1.6 x 104

Zachary adds 26.64 g to 12.557 g. How many significant figures should his answer have?

two

three

four

five

The balanced equation below shows the products that are formed when pentane (C5H12) is combusted. C5H12 + 8O2 5CO2 + 6H2OWhat is the mole ratio of oxygen to pentane?

1:6

6:8

8:1

5:8

Which expression is equal to the number of grams (g) in 2.43 kilograms (kg)?

2.43 kilograms times StartFraction 1000 grams over 1 kilogram EndFraction.

2.43 grams times StartFraction 1 kilogram over 1000 grams EndFraction.

StartFraction 1 over 2.43 kilograms EndFraction times StartFraction 1000 grams over 1 kilogram EndFraction.

StartFraction 1 over 2.43 kilograms EndFraction times StartFraction 1 kilogram over 1000 grams EndFraction.

The hydrogen ion concentration of a vinegar solution is 0.00010 M. How is this concentration written in scientific notation?

1.0 10–5 M

1.0 10–4 M

1.0 104 M

1.0 105 M

Consider the balanced equation below. 2H2S + 3O2 2SO2 + 2H2OWhich option gives the correct mole ratios?

H2S:SO2 = 2:2 and O2:H2O = 3:2

H2S:SO2 = 2:3 and O2:H2O = 3:2

H2S:SO2 = 4:4 and O2:H2O = 5:4

H2S:SO2 = 4:6 and O2:H2O = 4:4

The volume of a sample of water is 2.5 milliliters (mL). The volume of this sample in liters (L) is

2.5 10–3 L.

2.5 10–2 L.

2.5 102 L.

2.5 103 L.

Which must be the same when comparing 1 mol of oxygen gas, O2, with 1 mol of carbon monoxide gas, CO?

the mass

the volume

the number of molecules

the number of oxygen atoms

Which statement best describes a mole?

It is used mainly for writing chemical formulas.

It is used for chemical equations that have reversible reactions.

It is used for directly comparing the amounts of substances.

It is used mainly for dealing with fluid substances.

The mass of a single atom of carbon can be found by dividing the atomic mass (12.01 g) by 6.022 1023. Which is the mass of a single carbon atom, correctly written in scientific notation with the correct number of significant figures?

1.99 10–23 g

1.994 10–23 g

2 10–23 g

2.0 10–23 g

Which is the molar mass of H2O?

10.02 g/mol

16.00 g/mol

17.01 g/mol

18.02 g/mol

Consider the balanced equation below.4NH3 + 3O2 2N2 + 6H2O What is the mole ratio of NH3 to N2?

2:4

4:2

4:4

7:2

The O–O bond length in oxygen gas is 1.20741 10–10 m. The atomic radius is exactly of the O–O bond length. Which is the atomic radius of oxygen, correctly written in scientific notation with the correct number of significant figures?