Question

1-\Naturally occurring copper exists in two isotopic forms: ⁶³Cu and⁶⁵Cu. The atomic mass of copper is 63.55 amu. What is the approximate natural abundance of ⁶³Cu?​

Select one:

a.

​63%

b.

​90%

c.

​70%

d.

​30%

e.

​50%

1-\The molar mass of the compound formed by potassium and sulfur is _____.  

Select one:

a.

​110.3 g/mol

b.

​135.3 g/mol

c.

​103.2 g/mol

d.

​71.2 g/mol

e.

​149.4 g/mol

How many oxygen atoms are there in one formula unit of Ca₃(PO₄)₂?

Select one:

a.

​none of these

b.

​2

c.

​4

d.

​6

e.

​8

​What is the molar mass of ethanol (C₂H₅OH)?

Select one:

a.

​34.06 g/mol

b.

​46.07 g/mol

c.

​105.03 g/mol

d.

​45.06 g/mol

e.

​30.03 g/mol

How many oxygen atoms are there in 3 formula units of Al(NO₃)₃?

Select one:

a.

​15

b.

​9

c.

​30

d.

​27

e.

​14

The molar mass of an insecticide, dibromoethane, is 187.9 g/mol. Its molecular formula is C₂H₄Br₂. What percent by mass of carbon does dibromoethane contain?

Select one:

a.

2.14%

b.

85.05%

c.

6.39%

d.

12.78%

e.

0.536%

​What is the molar mass of cryolite (Na₃AlF₆)?

Select one:

a.

​185.3 g/mol

b.

​104.2 g/mol

c.

​210.0 g/mol

d.

​209.9 g/mol

e.

​68.97 g/mol

Each molecule of lycopene contains 40 atoms of carbon (plus other atoms). The mass percent of carbon in lycopene is 84.49%. What is the molar mass of lycopene?

Select one:

a.

1137.2 g/mol

b.

568.6 g/mol

c.

480.4 g/mol

d.

405.9 g/mol

e.

473.4 g/mol

​Calculate the molar mass of magnesium sulfite.

Select one:

a.

​288.83 g/mol

b.

​120.38 g/mol

c.

​104.38 g/mol

d.

​128.69 g/mol

e.

​88.38 g/mol

How many atoms of hydrogen are present in 6.43 g of ammonia?

Select one:

a.

​2.27 × 10²³

b.

​9.41 × 10¹⁹

c.

​1.16 × 10²⁵

d.

​6.82 × 10²³

e.

​1.28 × 10²⁴

​A given sample of a xenon fluoride compound contains molecules of a single type XeF_n, where n is some whole number. Given that 8.86 × 10²⁰ molecules of XeF_n weigh 0.361 g, calculate n.

Select one:

a.

​3

b.

​2

c.

​1

d.

​6

e.

​4

What would be the g Al / mole S ratio for the product of a reaction between aluminum and sulfur?

Select one:

a.

53.96 g Al / mol S

b.

17.99 g Al / mol S

c.

26.98 g Al / mol S

d.

40.47 g Al / mol S

e.

80.94 g Al / mol S

How many grams of potassium are in 15.0 g of K₂CrO₇?

Select one:

a.

4.84 g

b.

2.42 g

c.

30.0 g

d.

78.2 g

e.

0.767 g

​How many moles of hydrogen sulfide are contained in a 39.3-g sample of this gas?

Select one:

a.

​19.5 mol

b.

​2.31 mol

c.

​0.867 mol

d.

​1.15 mol

e.

​73.4 mol

Nitric acid, HNO₃, contains what percent hydrogen by mass?

Select one:

a.

2.22%

b.

3.25%

c.

20.0%

d.

1.60%

e.

25.4%

The mineral mimetite has the formula Pb₅(AsO₄)₃Cl. What mass percent of oxygen does it contain?

Select one:

a.

12.90 %

b.

38.70 %

c.

50.32 %

d.

1.08 %

e.

16.34 %

Which compound contains the highest percent by mass of hydrogen?

Select one:

a.

H₂SO₄

b.

HF

c.

H₂S

d.

H₂O

e.

HCl

A hydrocarbon (a compound consisting solely of carbon and hydrogen) is found to be 85.6% carbon by mass. What is the empirical formula for this compound?

Select one:

a.

C₃H

b.

CH₄

c.

CH

d.

C₂H

e.

CH₂

Adipic acid contains 49.32% C, 43.84% O, and 6.85% H by mass. What is the empirical formula?

Select one:

a.

C₃HO₃

b.

C₃H₃O₄

c.

C₂H₅O₄

d.

C₂HO₃

e.

C₃H₅O₂

The empirical formula of a group of compounds is CHCl. Lindane, a powerful insecticide, is a member of this group. The molar mass of lindane is 290.8 g/mol. How many atoms of carbon does a molecule of lindane contain?

Select one:

a.

3

b.

8

c.

4

d.

6

e.

2

The empirical formula of styrene is CH; its molar mass is 104.1 g/mol. What is the molecular formula of styrene?

Select one:

a.

C₈H₈

b.

C₆H₆

c.

C₁₀H₁₂

d.

C₂H₄

e.

none of these

A reaction occurs between sodium carbonate and hydrochloric acid producing sodium chloride, carbon dioxide, and water. The correct set of coefficients, respectively, for the balanced reaction is:

Select one:

a.

8 6 5 10 5

b.

3 6 6 3 4

c.

none of these

d.

1 2 2 1 1

e.

5 10 10 5 5

Which of the following equations correctly describes the combustion of CH₄ and O₂ to produce water (H₂O) and carbon dioxide (CO₂)?

Select one:

a.

CH₄ + O₂ → CO₂ + H₂O

b.

CH₄ + 2O₂ → CO₂ + 2H₂O

c.

2CH₄ + 3O₂ → 2CO₂ + 2H₂O

d.

CH₄ + O₂ → CO₂ + 2H₂O

e.

CH₄ + 3O₂ → 2CO₂ + H₂O

Give (in order) the correct coefficients to balance the following reaction:
H₂SnCl₆ + H₂S → SnS₂ + HCl

Select one:

a.

6, 2, 1, 1

b.

1, 1, 1, 6

c.

1, 2, 1, 6

d.

1, 2, 2, 2

e.

2, 4, 2, 6

​How many of the following are true concerning balanced chemical equations?

I.   The number of molecules is conserved.

II. The coefficients for the reactants tell you how much of each reactant you are given.

III. Atoms are neither created nor destroyed.

IV. The coefficients indicate the mass ratios of the substances used.

V.   The sum of the coefficients on the reactant side equals the sum of the coefficients on the product side.

Select one:

a.

​3

b.

​1

c.

​2

d.

​4

e.

​5

Answer 1