Question 1

A compound has an empirical formula of C2H2O. If its molecular weight is 168 g/mol, the molecular formula of this compound is ___________.

Accepted Answer

C8H8O4

Answer

C4H4O2

Answer

C6H6O3

Answer

C3H6O3

Question 2

Which of the following is an example of a molecular formula?

Accepted Answer

C2H4O

Answer

CH (Acetylene)

Answer

CH2O (Formaldehyde)

Answer

CH2 (Ethylene)

Question 3

What is the correct molecular weight of NH3?

Accepted Answer

17 g/mol

Answer

18 g/mol

Answer

19 g/mol

Answer

20 g/mol

Question 4

Which of the following gives the actual number of atoms present in a chemical compound?

Accepted Answer

Molecular formula

Answer

Structural formula

Answer

Chemical formula

Answer

Empirical formula

Question 5

What is the molar mass of barium perchlorate, Ba(ClO4)2?

Accepted Answer

336.24 g/mol

Answer

179.20 g/mol

Answer

292.14 g/mol

Answer

245.14 g/mol

Question 6

Which of the following is an example of an empirical formula?

Accepted Answer

C7H6O2

Answer

C6H8O6 (Ascorbic acid)

Answer

C2H6O2 (Ethylene glycol)

Answer

C4H8O2 (Butanoic acid)

Question 7

Calculate the percent by mass of nitrogen in (NH4)2CO3. (Molar mass = 96.09 g/mol)

Accepted Answer

35.9%

Answer

29.1%

Answer

41.1%

Answer

39.1%

Question 8

In a 100 g sample of a substance, 85.6% is carbon and 14.4% is hydrogen. How much carbon in grams is in the sample of substance?

Accepted Answer

85.6 g

Answer

12.0 g

Answer

14.0 g

Answer

856.0 g

Question 9

What is the mass percentage of oxygen in Al(OH)3?

Accepted Answer

61.5%

Answer

49.8%

Answer

70.5%

Answer

72.1%

Question 10

A given sample of substance is composed of 53.3% carbon, 11.1% hydrogen, and 35.6% oxygen and has a molecular mass of 1.1 g/mol.

What is the empirical formula for this substance?

Accepted Answer

C2H5O

Answer

C5H9O

Answer

C3H7O

Answer

C7H5O

Question 11

A given sample of substance is composed of 53.3% carbon, 11.1% hydrogen, and 35.6% oxygen and has a molecular mass of 1.1 g/mol. What is the empirical formula for this substance?

What is the molecular formula of the substance in the question?

Accepted Answer

C6H12O4

Answer

C2H4O2

Answer

C4H10O2

Answer

C6H18O6

Question 12

What is the empirical formula of a compound with the molecular formula C12H24O6?

Accepted Answer

C6H12O3

Answer

CHO

Answer

C12H24O6

Answer

C2H4O

Question 13

Which term describes the ratio of the amount of each element to the total amount of individual elements in a compound multiplied by 100?

Accepted Answer

Percent composition

Answer

Percent yield

Answer

Molar ratio

Answer

Probability ratio

Question 14

How many moles are in 50.05 g of sulfur (Atomic mass = 32.06 g/mol)?

Accepted Answer

1.56 mol

Answer

1.60 mol

Answer

2.00 mol

Answer

1.50 mol

Question 15

What is the empirical formula for a compound containing 37.47% carbon, 12.61% hydrogen, and 49.92% oxygen by mass?

Accepted Answer

CH2O

Answer

C2H5O

Answer

C3H4O

Answer

CH4O

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