Question 1

Which of the following best describes the difference between a scientific theory and a scientific law?

Accepted Answer

A scientific theory provides an explanation for observations and laws, while a law summarizes observed patterns in nature.

Question 2

A student measures the mass of a metal sample three times and obtains values of 10.2 g, 10.3 g, and 10.2 g. The true mass is 12.0 g. Which statement best describes the accuracy and precision of the measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is an example of a chemical change?

Accepted Answer

Rusting of an iron nail.

Question 4

A sample of ethanol has a density of $$0.789\ \mathrm{g/mL}. $$What is the mass, in grams, of $$25.0\ \mathrm{mL} of $$ethanol?

Accepted Answer

$$31.6$$

Question 5

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 6

Which scientist is credited with the discovery of the electron, and what experiment led to this discovery?

Accepted Answer

J.J. Thomson; cathode ray tube experiment

Question 7

A compound contains $$40.0\%$$ carbon, $$6.7\%$$ hydrogen, and $$53.3\%$$ oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 8

Which of the following best describes the Law of Multiple Proportions as proposed by John Dalton?

Accepted Answer

When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in ratios of small whole numbers.

Question 9

How many atoms are present in $$2.00$$ moles of magnesium?

Accepted Answer

$$1.20 	imes 10$$^{24}$$

Question 10

Which of the following is an extensive property?

Accepted Answer

Mass

Question 11

A student needs to convert $$350.0\ \mathrm{K} to $$degrees Celsius. Which equation should they use, and what is the answer?

Accepted Answer

$$T_{\mathrm{C}} = T_{\mathrm{K}} - 273.15;\ 76.85\ ^\circ\mathrm{C}$$

Question 12

Which of the following compounds is named correctly?

Accepted Answer

NaCl: sodium chloride

Question 13

Which of the following best describes the difference between correlation and causation?

Accepted Answer

Correlation means two variables are related, but causation means one variable directly affects the other.

Question 14

A sample contains $$3.00$$ grams of hydrogen ($$\mathrm{H}). $$How many moles of hydrogen atoms are present? (Atomic mass of H = $$1.01\ \mathrm{g/mol})$$

Accepted Answer

$$2.97$$ moles

Question 15

Which of the following is a correct statement about the periodic table as organized by Mendeleev?

Accepted Answer

Elements are arranged in order of increasing atomic mass, and elements with similar properties are in the same column.

Question 16

Which of the following is the correct formula for the compound formed between aluminum and sulfate?

Accepted Answer

$$\mathrm{Al}_2(\mathrm{SO}_4)_3$$

Question 17

A hydrate of magnesium sulfate has a formula $$\mathrm{MgSO}_4 \cdot x\mathrm{H}_2\mathrm{O}. If a$$ $$5.00 g $$sample of the hydrate is heated and $$2.44 g of $$anhydrous $$\mathrm{MgSO}_4$$ remains, what is the value of $$x$$? (Molar mass: $$\mathrm{MgSO}_4 = 120.4\ \mathrm{g/mol}$$, $$\mathrm{H}_2\mathrm{O} = 18.02\ \mathrm{g/mol})$$

Accepted Answer

$$x = 7$$

Question 18

Which of the following is a polyatomic ion?

Accepted Answer

$$\mathrm{NO}_3^-$$

Question 19

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electrons between two nonmetals.

Question 20

A sample of gas at $$25.0\ ^\circ\mathrm{C} is $$heated to $$75.0\ ^\circ\mathrm{C}. By $$how many Kelvin did the temperature increase?

Accepted Answer

$$50.0\ \mathrm{K}$$

CHM165 Exam 1 Study Guide: Chapters 1-3 (Matter, Atoms, Molecules, and Compounds)

Study Guide - Practice Questions

Study Guide - Flashcards