Question 1

Which of the following statements best describes the difference between a hypothesis and a scientific theory?

Accepted Answer

A hypothesis is a tentative explanation that can be tested, while a scientific theory is a well-substantiated explanation based on a body of evidence.

Question 2

A sample of a substance is observed to have a definite shape and volume. Which state of matter does this sample most likely represent?

Accepted Answer

Solid

Question 3

Which of the following is an example of a heterogeneous mixture?

Accepted Answer

Salad dressing with oil and vinegar

Question 4

Which process is a physical change rather than a chemical change?

Accepted Answer

Melting of ice

Question 5

A student measures the mass of a sample three times and gets values that are very close to each other, but far from the true value. This set of measurements is:

Accepted Answer

Precise but not accurate

Question 6

Convert $$25.0 \, ^\circ\mathrm{C} to $$Kelvin.

Accepted Answer

$$298.2 \, \mathrm{K}$$

Question 7

Which of the following best describes the law of conservation of mass?

Accepted Answer

The total mass of substances present after a chemical reaction is the same as the total mass before the reaction.

Question 8

Which experiment provided evidence for the existence of the electron?

Accepted Answer

J. J. Thomson's cathode ray tube experiment

Question 9

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

Accepted Answer

$$^{35}\mathrm{Cl}$$

Question 10

Which of the following elements is an alkali metal?

Accepted Answer

Sodium

Question 11

How many moles are in $$3.01 	imes 10$$^{23}$$ molecules of water?

Accepted Answer

$$0.500$$ moles

Question 12

Which of the following compounds is held together by ionic bonds?

Accepted Answer

$$\mathrm{NaCl}$$

Question 13

What is the empirical formula of a compound that contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 14

Which of the following is a correct name for $$\mathrm{FeCl}_3$$?

Accepted Answer

Iron(III) chloride

Question 15

A sample contains $$0.250$$ moles of $$\mathrm{Na}_2\mathrm{SO}_4. $$How many formula units are present in the sample? ($$1$$ mole $$= 6.022 	imes 10$$^{23}$$ particles)

Accepted Answer

$$1.51 	imes 10$$^{23}$$

Question 16

Which of the following is a chemical property?

Accepted Answer

Flammability

Question 17

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 18

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

Accepted Answer

$$\mathrm{N}_2\mathrm{O}_5$$

Question 19

A compound is found to contain $$24.0 g of $$carbon, $$4.0 g of $$hydrogen, and $$32.0 g of $$oxygen. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{C}_2\mathrm{H}_4\mathrm{O}_2$$

Question 20

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements in the same group have similar chemical properties.

General Chemistry I: Study Guide – Matter, Measurement, Atoms, and Compounds

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