Question 1

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture in which the composition is uniform throughout and individual components are not distinguishable.

Question 2

Which of the following is a chemical property?

Accepted Answer

Reactivity with oxygen

Question 3

A student observes a color change and the production of a gas when two solutions are mixed. What type of change has most likely occurred?

Accepted Answer

A chemical change

Question 4

Which method would be most appropriate to separate a mixture of sand and salt dissolved in water?

Accepted Answer

Filtration followed by evaporation

Question 5

Which of the following statements about significant figures is correct?

Accepted Answer

Zeros between nonzero digits are significant.

Question 6

Given the following measurements: $$2.34$$, $$2.3$$, and $$2.345$$, what is the correct sum, reported with the appropriate number of significant figures?

Accepted Answer

$$6.99$$

Question 7

Which subatomic particle determines the identity of an element?

Accepted Answer

Proton

Question 8

An atom has an atomic number of $$17$$ and a mass number of $$37. $$How many neutrons does it have?

Accepted Answer

$$20$$

Question 9

Which of the following best explains why the atomic radius decreases across a period in the periodic table?

Accepted Answer

The nuclear charge increases, pulling electrons closer to the nucleus.

Question 10

A sample of chlorine contains $$75.77\%$$ $$^{35}\mathrm{Cl} ($$atomic mass $$34.969 u) $$and $$24.23\%$$ $$^{37}\mathrm{Cl} ($$atomic mass $$36.966 u). $$What is the relative atomic mass of chlorine? (Round to two decimal places)

Accepted Answer

$$35.45$$

Question 11

Which of the following is a physical change?

Accepted Answer

Melting of ice

Question 12

Which of the following best describes a pure substance?

Accepted Answer

A material with a fixed composition and distinct properties.

Question 13

Which physical method would best separate a mixture of two liquids with different boiling points?

Accepted Answer

Distillation

Question 14

Which of the following is NOT evidence of a chemical change?

Accepted Answer

Melting of a solid

Question 15

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 16

Which trend is observed as you move down a group in the periodic table?

Accepted Answer

Atomic radius increases.

Question 17

A student measures the mass of a sample three times and records $$12.34 g$$, $$12.31 g$$, and $$12.36 g. $$What is the best way to report the average mass with appropriate uncertainty?

Accepted Answer

$$12.34 \pm 0.03 g$$

Question 18

Which of the following best explains why ionization energy generally increases across a period?

Accepted Answer

The effective nuclear charge increases, making it harder to remove an electron.

Question 19

Which of the following is an example of a heterogeneous mixture?

Accepted Answer

Salad dressing with oil and vinegar

Question 20

Which of the following best describes the change of state from liquid to gas?

Accepted Answer

Evaporation

Matter, Chemical Trends, and Chemical Bonding: Study Guide

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