Question 1

Which of the following best describes the difference between a physical and a chemical change? Consider the rusting of iron and the melting of ice.

Accepted Answer

Rusting of iron is a chemical change because it forms a new substance, while melting of ice is a physical change because the composition of water remains the same.

Question 2

A sample of magnesium has a mass of 24.305 g and occupies a volume of 13.2 cm$$^3. $$What is the density of magnesium? (Give your answer to the correct number of significant figures.)

Accepted Answer

$$1.84\ \mathrm{g/cm^3$}$$

Question 3

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 4

A student finds a clear, colorless liquid in the laboratory. Which of the following would best help determine if it is an element or a compound?

Accepted Answer

Test if it can be separated into simpler substances by chemical means.

Question 5

Which of the following is the correct name for the compound $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 6

A sample of chlorine contains 75.77% $$^{35}\mathrm{Cl} ($$mass = 34.969 amu) and 24.23% $$^{37}\mathrm{Cl} ($$mass = 36.966 amu). What is the average atomic mass of chlorine? (Show your calculation.)

Accepted Answer

$$35.45\ \mathrm{amu}$$

Question 7

Which of the following best describes an endothermic process?

Accepted Answer

A process that absorbs heat from the surroundings, such as the melting of ice.

Question 8

Convert a temperature of $$-40^\circ\mathrm{C} to $$Fahrenheit using the appropriate formula.

Accepted Answer

$$-40^\circ\mathrm{F}$$

Question 9

Which of the following numbers has the greatest number of significant figures?

Accepted Answer

0.004560

Question 10

A block of unknown material has a mass of 210 g and a density of $$7.0\ \mathrm{g/cm^3$}. $$What is its volume?

Accepted Answer

$$30\ \mathrm{cm^3$}$$

Question 11

Which of the following is a chemical property?

Accepted Answer

Ability to react with oxygen

Question 12

Which of the following best explains why water ($$\mathrm{H_2O}) is $$classified as a compound?

Accepted Answer

It consists of two different elements chemically combined in a fixed ratio.

Question 13

A neutral atom of $$^{27}\mathrm{Al}$$ has how many protons, neutrons, and electrons?

Accepted Answer

13 protons, 14 neutrons, 13 electrons

Question 14

Which of the following is the correct name for the compound $$\mathrm{N_2O_4}$$?

Accepted Answer

Dinitrogen tetroxide

Question 15

A student dissolves table salt ($$\mathrm{NaCl}) in $$water and observes that the salt disappears. Which type of change has occurred?

Accepted Answer

Physical change, because no new substances are formed.

Question 16

Which of the following best describes the energy change in an exothermic reaction?

Accepted Answer

Energy is released to the surroundings, causing the temperature to increase.

Question 17

A sample of gas has a mass of 0.250 g and occupies a volume of 125 mL. What is its density in $$\mathrm{g/mL}$$?

Accepted Answer

$$0.0020\ \mathrm{g/mL}$$

Question 18

Which of the following is the correct formula for diphosphorus pentoxide?

Accepted Answer

$$\mathrm{P_2O_5}$$

Question 19

A patient is given a medication that must be stored at $$5^\circ\mathrm{C}. $$What is this temperature in Kelvin?

Accepted Answer

$$278\ \mathrm{K}$$

Question 20

A gold bar has a volume of $$50.0\ \mathrm{cm^3$}$$ and a density of $$19.3\ \mathrm{g/cm^3$}. $$What is its mass?

Accepted Answer

$$965\ \mathrm{g}$$

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

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