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 vinegar, which is composed of approximately 5% acetic acid and 95% water. Which of the following is the best classification for vinegar?

Accepted Answer

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?

$$	ext{mass} = 	ext{density} 	imes 	ext{volume}$$

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

A person weighs 150 lb on Earth. What would be their weight on Mars, where gravity is one-third that of Earth?

Accepted Answer

$$50 lb$$

Question 6

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 7

If 32 g of sulfur reacts with 48 g of oxygen to produce 80 g of sulfur trioxide, what is the mass of material in a sealed container after 16 g of sulfur and 100 g of oxygen are allowed to react completely?

Accepted Answer

$$116 g$$

Question 8

Which experiment led to the nuclear model of the atom?

Accepted Answer

Alpha particle scattering by thin metal foils

Question 9

A neutral atom of iron (Fe) has 26 protons. Which of the following statements is true for all naturally occurring isotopes of iron?

Accepted Answer

They all have 26 protons, 26 electrons, and different numbers of neutrons.

Question 10

Which of the following electron configurations is impossible?

Accepted Answer

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

Question 11

How many micrograms are in 20 mg?

$$1\ 	ext{mg} = 1000\ \mu	ext{g}$$

Accepted Answer

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

Question 12

Which of the following statements about the electron is supported by Millikan's oil drop experiment?

Accepted Answer

The charge of the electron

Question 13

Which of the following best describes a cation?

Accepted Answer

A positively charged ion

Question 14

A sample of water has a mass of 22.00 grams and a volume of 10.0 mL. What is its density?

$$	ext{Density} = \frac{	ext{mass}}{	ext{volume}}$$

Accepted Answer

$$2.20\ 	ext{g/mL}$$

Question 15

Which of the following is a real-world example of green chemistry?

Accepted Answer

Replacing mercury thermometers with alcohol thermometers

Question 16

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

Accepted Answer

Quantized

Question 17

A student is given 20.0 grams of CH$$_4 ($$methane). How many grams of carbon are present in this sample?

$$	ext{Molar mass of CH}_4 = 12.01 + 4 	imes 1.008 = 16.042\ 	ext{g/mol}$$ 
$$	ext{Fraction of C} = \frac{12.01}{16.042}$$ 
$$	ext{Mass of C} = 20.0 	imes \frac{12.01}{16.042}$$

Accepted Answer

$$14.98$$ grams

Question 18

Which of the following is true about a neutral atom?

Accepted Answer

It has the same number of electrons and protons.

Question 19

Which of the following best describes the pattern of colors emitted by excited atoms?

Accepted Answer

A line spectrum

Question 20

Which of the following elements is a noble gas?

Accepted Answer

Xe

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

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