Question 1

Which of the following best describes a chemical change?

Accepted Answer

Passing an electric current through water to produce hydrogen and oxygen gases

Question 2

Which statement about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 3

A sample of carbon contains 98.9% $$^{12}C ($$mass = 12.000 amu) and 1.1% $$^{13}C ($$mass = 13.003 amu). What is the average atomic mass of carbon? (Round to two decimal places.)

Accepted Answer

$$12.01$$ amu

Question 4

Which of the following is a homogeneous mixture?

Accepted Answer

Sea water

Question 5

According to Dalton's Atomic Theory, which statement is FALSE?

Accepted Answer

Atoms of an element can change into atoms of another element during a chemical reaction.

Question 6

Which of the following is a pure chemical substance?

Accepted Answer

Oxygen gas ($$O_2)$$

Question 7

A sample contains $$3.01 	imes 10$$^{23}$$ atoms of copper. How many moles of copper are present?

Accepted Answer

$$0.50$$ mol

Question 8

Which of the following best explains why water is considered a compound?

Accepted Answer

It is composed of two or more elements chemically bonded in a fixed ratio.

Question 9

Which law states that in a chemical reaction, matter is neither created nor destroyed?

Accepted Answer

Law of Conservation of Mass

Question 10

A neutral atom of sodium ($$Na) $$has an atomic number of 11 and a mass number of 23. How many neutrons does it have?

Accepted Answer

12

Question 11

Which of the following is a physical change?

Accepted Answer

Boiling water to produce steam

Question 12

Which of the following statements about ions is correct?

Accepted Answer

Cations are formed when atoms lose electrons.

Question 13

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture with non-uniform composition throughout

Question 14

Which of the following is the correct chemical symbol for an atom with 6 protons, 6 neutrons, and 6 electrons?

Accepted Answer

$$^{12}_{6}C$$

Question 15

Which of the following best describes the Law of Definite Proportion?

Accepted Answer

A compound always contains the same elements in the same proportion by mass.

Question 16

A sample of water contains $$1.00$$ mol of $$H_2O. $$How many molecules of water are present?

Accepted Answer

$$6.022 	imes 10$$^{23}$$

Question 17

Which of the following is NOT a property of a solid state of matter?

Accepted Answer

Particles can move freely past each other.

Question 18

Which of the following best explains why helium is a noble gas?

Accepted Answer

It has a full outer electron shell, making it chemically unreactive.

Question 19

Which of the following is the correct order of steps to calculate the number of atoms in a given mass of an element?

Accepted Answer

Divide mass by molar mass, then multiply by Avogadro's number

Question 20

Which of the following is a correct statement about the atomic number of an element?

Accepted Answer

It is the number of protons in the nucleus.

General Chemistry Fundamentals: Matter, Atomic Theory, Elements, Compounds, and Chemical Transformations

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