Q: How many atoms are in $$2.00$$ moles of carbon?

$$1.20 \times 10$$^{24}$$ atoms

Question 1

Which of the following statements best describes the difference between precision and accuracy in scientific measurements?

Accepted Answer

Precision refers to how close repeated measurements are to each other, while accuracy refers to how close a measured value is to the true value.

Question 2

A student measures the mass of a sample as $$12.30\ \mathrm{g}$$, $$12.31\ \mathrm{g}$$, and $$12.29\ \mathrm{g}$$, but the true mass is $$12.80\ \mathrm{g}. $$Which of the following best describes the measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is an example of a systematic error?

Accepted Answer

A balance that is not zeroed before measuring every sample.

Question 4

Which of the following numbers contains three significant figures?

Accepted Answer

$$0.0300$$

Question 5

When multiplying $$2.34 ($$three significant figures) by $$1.2 ($$two significant figures), how many significant figures should the answer have?

Accepted Answer

Two

Question 6

Which of the following is an exact number?

Accepted Answer

The number of centimeters in a meter

Question 7

A cube has sides of length $$2.0\ \mathrm{cm}. $$What is its volume in $$\mathrm{cm}^3$$ and $$\mathrm{mL}$$?

Accepted Answer

$$8.0\ \mathrm{cm}^3$$ and $$8.0\ \mathrm{mL}$$

Question 8

Which of the following best describes an intensive property?

Accepted Answer

A property that does not depend on the amount of substance present, such as density.

Question 9

Which of the following is a chemical change?

Accepted Answer

Rusting of iron

Question 10

Which of the following best describes the Law of Conservation of Mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 11

A sample of ethanol has a density of $$0.789\ \mathrm{g/mL}. $$What is the mass of $$25.0\ \mathrm{mL} of $$ethanol?

Accepted Answer

$$19.7\ \mathrm{g}$$

Question 12

Which of the following changes of state requires an input of energy?

Accepted Answer

Sublimation

Question 13

Which of the following is a heterogeneous mixture?

Accepted Answer

Sand and iron filings

Question 14

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 15

Which scientist's experiment led to the discovery of the nucleus in the atom?

Accepted Answer

Ernest Rutherford

Question 16

A neutral atom of sodium ($$^{23}_{11}\mathrm{Na}) $$has how many protons, neutrons, and electrons?

Accepted Answer

11 protons, 12 neutrons, 11 electrons

Question 17

Which of the following is the correct way to write the chemical symbol for an atom with atomic number $$Z$$ and mass number $$A$$?

Accepted Answer

$$^{A}_{Z}\mathrm{X}$$

Question 18

How many atoms are in $$2.00$$ moles of carbon?

Accepted Answer

$$1.20 	imes 10$$^{24}$$ atoms

Question 19

What is the molar mass of $$\mathrm{C}_2\mathrm{H}_6\mathrm{O} ($$ethanol)?

Accepted Answer

$$46.07\ \mathrm{g/mol}$$

Question 20

A sample contains $$18.0\ \mathrm{g} of $$water ($$\mathrm{H}_2\mathrm{O}). $$How many moles of water are present?

Accepted Answer

$$1.00$$ mole

General Chemistry: Measurements, Concepts, and Atomic Theory Study Guide

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