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Chemistry Unit 8 WS 5-7 Quiz Practice

Total questions: 20

Worksheet time: 39mins

Name
Class
Date
1.

Which type of formula describes the actual number of each element in a molecule or compound?

a)

Empirical formula

b)

Molecular formula

c)

Structural formula

d)

Simplified formula

2.

Which type of formula describes the lowest whole-number ratio of the elements in a compound?

a)

Empirical formula

b)

Molecular formula

c)

Structural formula

d)

Simplified formula

3.

If methane, CH₄, is 75% carbon, then 100 grams of methane contains how many grams of hydrogen?

a)

25 grams

b)

50 grams

c)

75 grams

d)

100 grams

4.
Find the Molar Mass of:
Ga2(SO3)3
a)
280 g/mol
b)
400 g/mol
c)
380 g/mol
d)
480 g/mol
5.
What is the percent composition of S in the formula (NH4)2S ?
a)
12.05%
b)
19.30%
c)
47.11%
d)
56.18%
6.

What percent of Zn3(PO4)2 is zinc?

a)

33.15%

b)

16.04%

c)

50.80%

d)

19.68%

7.

Determine the percent composition of each of the elements in Al₂(SO₄)₃.

a)

Al: 18.8%, S: 21.1%, O: 60.1%

b)

Al: 10.5%, S: 32.1%, O: 57.4%

c)

Al: 15.8%, S: 28.1%, O: 56.1%


d)

Al: 20.2%, S: 24.1%, O: 55.7%

8.

What is the empirical formula for a compound that is 54.48% carbon, 13.75% hydrogen, and 31.77% nitrogen?

a)

C4H10N

b)

C2H6N

c)

CH4N

d)

C3H7N

9.

What is the empirical formula of a substance with the molecular formula Se8F12?

a)

Se8F12

b)

Se2F3

c)

Se4F3

d)

SeF

10.

What is the empirical formula of a substance with the molecular formula X20Y15?

a)

X10Y15

b)

X5Y3

c)

X4Y3

d)

X20Y15

11.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6Oand C2H6O2
d)
CH4 and C2H6
12.

What is the molecular formula of this substance?

a)

C2H2

b)

C2H2

c)

C2H6

d)

CH2

13.
What is the total number of atoms in this molecule?
a)
10
b)
5
c)
15
d)
20
14.
What is the molecular formula for a compound with the empirical formula: K2SOand a molecular mass of 696g.
a)
K2SO
b)
K8SO16
c)
K8S4O
d)
K8S4O16 
15.

What is the molecular formula for a compound that is 39.99% carbon, 6.73% hydrogen, and 53.28% oxygen and has a molar mass of 180.18g?

a)

C6H12O6

b)

C4H8O4

c)

C3H6O3

d)

C5H10O5

16.
Glycerol has a molar mass of 92.09g/mol. Its percent composition is: 39.12% C, 8.75% H, and 51.12% O. What is the molecular formula for glycerol?
a)
C2H3O2
b)
CH2O
c)
C2H4O2
d)
C3H8O3
17.

What is the empirical formula of K2SO4?

a)

K2SO4

b)

KSO2

c)

K2SO2

d)

KSO8

18.
Which one is an empirical formula?
a)
H2O2
b)
C2H6O12
c)
CaCl2
d)
N2O8
19.

Empirical and molecular formulas are never the same for any compound.

a)

True

b)

False

20.

The actual chemical formula for 3 compounds is shown below. Select the compound that has an identical empirical and molecular formula.

a)

b)

c)