Q: How many molecules are present in $$0.75$$ mole of $$CO_2$$?

$$1.13 \times 10$$^{24}$$ molecules

Q: How many atoms of oxygen are in $$0.200$$ mole of aspirin ($$C_9H_8O_4$$)?

$$4.82 \times 10$$^{23}$$ atoms

Question 1

Which statement best describes Avogadro's number?

Accepted Answer

It is the number of particles in one mole of a substance, equal to $$6.02 	imes 10$$^{23}$$.

Question 2

How many molecules are present in $$0.75$$ mole of $$CO_2$$?

Accepted Answer

$$1.13 	imes 10$$^{24}$$ molecules

Question 3

A sample contains $$3.0 	imes 10$$^{24}$$ atoms of sulfur. How many moles of sulfur are present?

Accepted Answer

$$4.98$$ moles

Question 4

How many atoms of oxygen are in $$0.200$$ mole of aspirin ($$C_9H_8O_4$$)?

Accepted Answer

$$4.82 	imes 10$$^{23}$$ atoms

Question 5

What is the molar mass of $$Na_2SO_4$$?

Accepted Answer

$$142.04 g/$$mol

Question 6

A patient is prescribed $$88.0 g of $$lithium carbonate ($$Li_2CO_3) $$for bipolar disorder. How many moles of $$Li_2CO_3 is $$this?

Accepted Answer

$$1.19$$ moles

Question 7

Which of the following is a balanced chemical equation?

Accepted Answer

$$2Mg(s) + O_2$(g) \rightarrow 2MgO(s)$$

Question 8

Which type of reaction is represented by $$2KClO_3(s) \rightarrow 2KCl(s) + 3O_2(g)$$?

Accepted Answer

Decomposition

Question 9

In the reaction $$Zn(s) + 2HCl(aq) \rightarrow $$ZnCl_2$$(aq) + H_2$(g)$$, which element is oxidized?

Accepted Answer

Zinc

Question 10

Which of the following best describes a combustion reaction?

Accepted Answer

A reaction in which a carbon-containing compound reacts with oxygen to produce $$CO_2$$ and $$H_2O.$$

Question 11

A sample of water has a mass of $$36.0 g. $$How many moles of water are present? ($$M_{H_2O} = 18.02 g/$$mol)

Accepted Answer

$$2.00$$ moles

Question 12

Which of the following changes will increase the rate of a chemical reaction?

Accepted Answer

Adding a catalyst

Question 13

In the reaction $$2Fe(s) + 3S(s) \rightarrow Fe_2S_3(s)$$, what is the mole ratio of $$Fe to$$ $$S$$?

Accepted Answer

$$2:3$$

Question 14

Which statement about catalysts is correct?

Accepted Answer

Catalysts lower the activation energy and are not used up.

Question 15

A reaction absorbs heat and the energy of the products is greater than the energy of the reactants. This reaction is:

Accepted Answer

Endothermic

Question 16

Which of the following is a double replacement reaction?

Accepted Answer

$$AgNO_3(aq) + $$NaCl(aq) \rightarrow AgCl(s) + $$NaNO_3(aq$$)$$

Question 17

Incomplete combustion of propane produces carbon monoxide. What is a major health risk associated with carbon monoxide exposure?

Accepted Answer

It binds to hemoglobin, reducing oxygen transport and causing symptoms like headache and dizziness.

Question 18

How many grams of $$O_2$$ are needed to produce $$45.3$$ grams of $$Fe_2O_3 in $$the reaction $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$? ($$M_{Fe_2O_3} = 159.7 g/$$mol, $$M_{O_2$} = 32.00 g/$$mol)

Accepted Answer

$$13.6 g$$

Question 19

Which of the following is NOT a condition required for a chemical reaction to occur?

Accepted Answer

Products must be gases.

Question 20

In the oxidation-reduction reaction $$2Cu(s) + O_2$(g) \rightarrow 2CuO(s)$$, which element is reduced?

Accepted Answer

Oxygen

Chemical Quantities and Reactions: Study Notes for GOB Chemistry

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