Question 1

Which of the following statements best describes a scientific hypothesis?

Accepted Answer

A hypothesis is a tentative explanation that can be tested and is falsifiable.

Question 2

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

Accepted Answer

The melting point of ice is $$0^\circ C.$$

Question 3

A sample of copper is hammered into a thin sheet. Which type of change has occurred?

Accepted Answer

Physical change, because the appearance changed but not the chemical structure.

Question 4

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture with uniform composition throughout, such as salt water.

Question 5

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

Accepted Answer

The ability of iron to react with oxygen to form rust.

Question 6

A student records the mass of a sample as $$0.00450 \ \mathrm{g}. $$How many significant figures are in this measurement?

Accepted Answer

3

Question 7

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

Accepted Answer

Water from any source always contains hydrogen and oxygen in a $$2:1$$ ratio by atoms.

Question 8

An atom has 17 protons, 18 neutrons, and 17 electrons. What is its mass number?

Accepted Answer

$$35$$

Question 9

Which of the following ions is a cation?

Accepted Answer

$$\mathrm{Na^+}$$

Question 10

What is the correct name for $$\mathrm{CO_2$}$$?

Accepted Answer

Carbon dioxide

Question 11

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 12

A student needs to convert $$25.0 \ \mathrm{cm} to $$meters using the cross-method. What is the correct answer?

Accepted Answer

$$0.250 \ \mathrm{m}$$

Question 13

Which of the following is the correct formula for copper(II) oxide?

Accepted Answer

$$\mathrm{CuO}$$

Question 14

How many protons and neutrons are in $$^{23}\mathrm{Na} ($$sodium-23)?

Accepted Answer

11 protons, 12 neutrons

Question 15

Which of the following is a polyatomic ion?

Accepted Answer

$$\mathrm{NO_3$^-}$$

Question 16

What is the correct name for $$\mathrm{Sr(NO_3$)_2}$$?

Accepted Answer

Strontium nitrate

Question 17

Which of the following best describes a chemical change?

Accepted Answer

Burning wood to produce ash and gases.

Question 18

Which group on the periodic table contains elements that are most likely to form $$+1$$ ions?

Accepted Answer

Group 1 (alkali metals)

Question 19

What is the correct name for $$\mathrm{$$CaCO_3$$}$$?

Accepted Answer

Calcium carbonate

Question 20

Which of the following numbers is correctly rounded to three significant figures?

Accepted Answer

$$0.00786$$ rounded to $$0.00786$$

General Chemistry Fundamentals: Concepts, Properties, and Atomic Structure

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