Question 1

Which of the following best describes a scientific hypothesis?

Accepted Answer

It is a tentative explanation that can be tested by experiments.

Question 2

A student is asked to classify a sample of vinegar, which contains 5% acetic acid and 95% water. Which is the best classification for vinegar?

Accepted Answer

It is a mixture.

Question 3

A 100.0 cm$$^3$$ block of steel has a density of 8.1 g/cm$$^3. $$What is its mass in grams? Use the formula $$	ext{mass} = 	ext{density} 	imes 	ext{volume}.$$

Accepted Answer

$$810.0 g$$

Question 4

Which of the following is a chemical property?

Accepted Answer

Potassium reacts with water to form potassium hydroxide.

Question 5

Convert $$20 mg to $$micrograms ($$\mug). $$Use the conversion $$1 mg$$ $$= 1000$$ $$\mug.$$

Accepted Answer

$$20,000$$ $$\mug$$

Question 6

A sealed container holds $$16 g of $$sulfur and $$100 g of $$oxygen. After a reaction, what is the total mass of material in the container? (Assume the Law of Conservation of Mass.)

Accepted Answer

$$116 g$$

Question 7

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

Accepted Answer

Heptane is always composed of $$84.0\%$$ carbon and $$16.0\%$$ hydrogen.

Question 8

How many grams of carbon are present in $$20.0$$ grams of CH$$_4$$? (Molar mass of CH$$_4 is$$ $$16.0 g/$$mol, and carbon is $$12.0 g/$$mol.)

Accepted Answer

$$15.0 g$$

Question 9

Which experiment led to the nuclear model of the atom?

Accepted Answer

Alpha particle scattering by thin metal foils

Question 10

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 11

Which of the following electron configurations is impossible?

Accepted Answer

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

Question 12

A neutral atom of gold (Au) has how many protons?

Accepted Answer

$$79$$

Question 13

Which of the following best describes a cation?

Accepted Answer

A positively charged ion

Question 14

Which type of radioactivity has a negative charge?

Accepted Answer

Beta ($$\beta) $$particles

Question 15

The maximum number of electrons that can occupy the $$n=2$$ energy level is:

Accepted Answer

$$8$$

Question 16

Which element is a nonmetal?

Accepted Answer

Chlorine

Question 17

Which of the following is equal to $$1 mL$$?

Accepted Answer

$$1 cm$^3$$

Question 18

A sample of a liquid has a mass of $$22.00$$ grams and a volume of $$10.0 mL. $$What is its density? Use $$	ext{density} = \frac{	ext{mass}}{	ext{volume}}.$$

Accepted Answer

$$2.20 g/mL$$

Question 19

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

Accepted Answer

The energy is quantized.

Question 20

Which of the following is an example of green chemistry?

Accepted Answer

Replacing mercury thermometers with alcohol thermometers

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

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