Question 1

Which of the following best describes a scientific hypothesis?

Accepted Answer

A tentative explanation that can be tested by experiments.

Question 2

A student wants to determine the density of a metal sample. She measures its mass as $$45.0\ \mathrm{g}$$ and its volume as $$15.0\ \mathrm{cm}^3. $$What is the density of the metal?

Accepted Answer

$$3.00\ \mathrm{g/cm}^3$$

Question 3

Which of the following is a chemical property?

Accepted Answer

Potassium reacts with water to form potassium hydroxide.

Question 4

A sealed container holds $$16\ \mathrm{g} of $$sulfur and $$100\ \mathrm{g} of $$oxygen. After a reaction, the total mass in the container is $$116\ \mathrm{g}. $$Which law does this observation best illustrate?

Accepted Answer

Law of Conservation of Mass

Question 5

Which of the following best describes a mixture?

Accepted Answer

A combination of two or more substances that retain their individual properties.

Question 6

A patient is given a dose of $$20\ \mathrm{mg} of a $$medication. How many micrograms is this?

Accepted Answer

$$20,000\ \mu\mathrm{g}$$

Question 7

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

Accepted Answer

Ice melts at $$0^\circ\mathrm{C}.$$

Question 8

Which of the following best illustrates the Law of Definite Proportions?

Accepted Answer

12 grams of carbon always combines with 32 grams of oxygen to form carbon dioxide.

Question 9

Which of the following statements about atoms and isotopes is correct?

Accepted Answer

All isotopes of an element have the same number of protons.

Question 10

A student is converting $$10.0\ \mathrm{cm} to $$meters. Which of the following is the correct conversion factor and answer?

Accepted Answer

$$1\ \mathrm{cm} = 0.01\ \mathrm{m}$$;\ \ 10.0\ \mathrm{cm} = 0.10\ \mathrm{m}$

Question 11

Which experiment led to the discovery that atoms are mostly empty space with a small, dense, positively charged nucleus?

Accepted Answer

Rutherford's gold foil experiment

Question 12

Which of the following electron configurations is impossible?

Accepted Answer

$$1s^3$$\ $$2s^2$$\ $$2p^5$$

Question 13

A sample of methane ($$\mathrm{CH}_4) $$has a mass of $$20.0\ \mathrm{g}. $$How many grams of carbon are present in the sample? (Molar mass of $$\mathrm{CH}_4 = 16.0\ \mathrm{g/mol}$$, C = $$12.0\ \mathrm{g/mol})$$

Accepted Answer

$$14.98\ \mathrm{g}$$

Question 14

Which of the following statements about the Bohr model of the atom is correct?

Accepted Answer

Electrons are found in fixed orbits with quantized energies.

Question 15

Which of the following best describes a cation?

Accepted Answer

A positively charged ion.

Question 16

A $$100.0\ \mathrm{cm}^3$$ block of steel has a density of $$8.1\ \mathrm{g/cm}^3. $$What is its mass?

Accepted Answer

$$810.0\ \mathrm{g}$$

Question 17

Which of the following is a correct statement about isotopes?

Accepted Answer

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

Question 18

Which of the following best describes the energy of electrons in atoms according to Bohr's model?

Accepted Answer

Electrons have quantized energy levels.

Question 19

A student is asked to identify the element with the ground state electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2. $$Which element is it?

Accepted Answer

Mg

Intro to Chemistry Exam 1 Review – Step-by-Step Study Guidance

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