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- 1. Multiple Choice
How many molecules are in 2.5 mol of NaCl?

1.50 x10

^{24 }molecules1.50 molecules

4.15 molecules

1.51 x10

^{24 }molecules - 2. Multiple Choice
How many moles are in 19.82 g Mg?

1.23 mol Mg

481.70 mol Mg

1.00 mol Mg

0.82 mol Mg

- 3. Multiple Choice
How many moles are in 3.01 x 10

^{22}atoms of magnesium?0.05 moles

1.81 x 10

^{46}moles5.00 x 10

^{21}moles5.00 moles

- 4. Multiple Choice
How many grams are in 1.2 x 10

^{24}atoms of C?29.34 grams

23.94 grams

6.02 grams

1.21 grams

- 5. Multiple Choice
What is the percent composition by mass of sulfur (S) in the compound MgSO

_{4}?20.22%

19.85%

26.64%

28.64%

- 6. Multiple ChoiceCalculate the number of atoms in 0.0340 g Zn.5.200 x 10
^{-4}atoms Zn3.130 x 10^{23}atoms Zn3.130 x 10^{20}atoms Zn1 atom Zn - 7. Multiple Choice
Determine the mass of 4.20 moles of C

_{6}H_{12}354 g

84 g

337 g

421 g

- 8. Multiple ChoiceWhich pair has the same empirical formula?NaCrO
_{4}and Na_{2}Cr_{2}O_{7}C_{2}H_{4}O_{2}and C_{6}H_{12}O_{6}C_{3}H_{6}O_{3 }and C_{2}H_{6}O_{2}CH_{4}and C_{2}H_{6} - 9. Multiple ChoiceWhat is the molar mass of PbSO
_{4}303.3 g/mol294.7g/mol163.8g/mol372g/mol - 10. Multiple Choice
How many grams are in 1.2 moles of Neon?

0.05 grams

16.6 grams

21.2 grams

24 grams

- 11. Multiple Choice
How many hydrogen atoms are in one formula unit of C2H4O2?

2

1

4

6

- 12. Multiple Choice
Use the given the chemical equation to answer the following question:

2C

_{2}H_{6}+ O_{2}→ 4CO_{2}+ 6H_{2}OWhat does the number 4 represent for the formula unit 4CO2 ?

The number 4 represents the coefficient, which is also equal to the number of grams of the formula unit above.

The number 4 represents the subscript, which is also equal to the number of moles of the formula unit above.

The number 4 represents the coefficient, which is also equal to the number of moles of the formula unit above.

The number 4 represents the subscript, which is also equal to the number of grams of the formula unit above.

- 13. Multiple Choice
How many grams of NH

_{3}would result in 8 moles of NH_{3. }What does the the number 8 do to the molar mass of the compound?The number 8 is added to the molar mass to give 25 g/mol.

The number 8 multiplies the molar mass by 8 to give 136 g/mol.

The number 8 divides the molar mass by 8 to give 2.13 g/mol.

The number 8 does not change the molar mass of the compound.

- 14. Multiple Choice
What is the chemical formula for calcium carbonate?

Ca(CO)3

CaCO3

CaC3

Ca3(OH)

- 15. Multiple Choice
Which of the following methods should be used in order to calculate the molar mass of magnesium hydroxide?

Add the masses of two moles Mg to the mass of one mole OH

Add the total protons and neutrons.

Add the masses of one mole Mg to the mass of one mole OH

Add the masses of one mole Mg to the masses of two moles of OH.

- 16. Multiple Choice
A student calculated the number of moles of methane (CH4) present in a 100g sample of a gaseous mixture. If the student determined that there’s 0.6 moles of methane present in the sample, what is the percent composition of methane in the sample?

.096%

9.6%

.9%

90%

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