Question 1

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the composition is not uniform and different parts can be visually distinguished, such as salad.

Question 2

Which step in the scientific method involves forming a testable explanation for an observation?

Accepted Answer

Formulating a hypothesis

Question 3

A student measures the mass of a sample as 2.50 g, 2.48 g, and 2.51 g in three trials. The true mass is 2.00 g. Which statement best describes the accuracy and precision of these measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 4

Which of the following is the correct scientific notation for 0.00056?

Accepted Answer

$$5.6 	imes 10$$^{-4}$$

Question 5

Which of the following is NOT a fundamental assumption of modern atomic theory?

Accepted Answer

Atoms are indivisible and cannot be broken down further.

Question 6

A neutral atom of magnesium (Mg) has an atomic number of 12. How many valence electrons does it have?

Accepted Answer

2

Question 7

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound consists of two or more elements chemically bonded, while a mixture consists of substances physically combined.

Question 8

Which metric prefix corresponds to $$10^{-6}$$?

Accepted Answer

micro-

Question 9

A sample contains $$3.0 	imes 10$$^{3}$$ milligrams of a substance. How many grams is this?

Accepted Answer

$$3.0$$ grams

Question 10

Which of the following elements is a noble gas?

Accepted Answer

Neon

Question 11

Which of the following methods is best for separating a mixture of sand and salt?

Accepted Answer

Filtration followed by evaporation

Question 12

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have the same number of valence electrons.

Question 13

A patient receives a dose of 0.25 mg of a medication. Express this dose in micrograms ($$\mug).$$

Accepted Answer

$$250 \ \mu\mathrm{g}$$

Question 14

Which of the following best explains why isotopes of the same element have different masses?

Accepted Answer

They have different numbers of neutrons.

Question 15

Which of the following is the correct formula for a molecule containing two hydrogen atoms and one oxygen atom?

Accepted Answer

$$\mathrm{H}_2\mathrm{O}$$

Question 16

Which of the following is the best definition of precision in scientific measurement?

Accepted Answer

How reproducible repeated measurements are.

Question 17

A sample of copper contains $$6.02 	imes 10$$^{23}$$ atoms. What is the mass of this sample if the atomic mass of copper is 63.5$ g/mol?

Accepted Answer

$$63.5$$ grams

Question 18

Which of the following is a physical property that can be used to separate substances in a mixture?

Accepted Answer

Boiling point

Question 19

Which of the following best describes the location of transition metals on the periodic table?

Accepted Answer

In the center block between groups 2 and 13

Question 20

A student needs to convert $$2.5$$ kilometers to meters. What is the correct conversion?

Accepted Answer

$$2,500$$ meters

Foundations of GOB Chemistry: Matter, Measurement, and the Periodic Table

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