$$43.9 \times 131.29 = 5762 g$$

$$2.26 \div 4.00 \times 6.022 \times 10$$^{23}$$ = 3.40 \times 10$$^{23}$$ atoms

$$1.1 \times 10$$^{21}$$ \div 6.022 \times 10$$^{23}$$ \times 197.0 = 0.36 g$$

Question 1

Which of the following statements best describes a chemical property?

Accepted Answer

It describes the way a substance may change or react to form other substances.

Question 2

A sample of matter has a constant composition and a fixed set of physical and chemical properties. Which term best describes this sample?

Accepted Answer

Compound

Question 3

Which of the following is NOT a postulate of Dalton’s Atomic Theory?

Accepted Answer

Atoms can be created or destroyed in chemical reactions.

Question 4

Which of the following best explains why sodium (Na) forms a $$+1$$ ion and chlorine (Cl) forms a $$-1$$ ion?

Accepted Answer

They tend to gain or lose electrons to achieve the same number of electrons as the nearest noble gas.

Question 5

Which of the following is the correct definition of a mole?

Accepted Answer

A unit defined as the amount of material containing $$6.022 	imes 10$$^{23}$$ elementary entities.

Question 6

Calculate the mass in grams of $$43.9$$ mol of xenon (Xe). (Atomic mass of Xe = $$131.29 g/$$mol)

Accepted Answer

$$43.9 	imes 131.29 = 5762 g$$

Question 7

A mixture is best described as:

Accepted Answer

A combination of two or more substances in which each retains its own identity and properties.

Question 8

Which of the following is a physical property?

Accepted Answer

Melting point

Question 9

Which law states that a chemical compound always contains exactly the same proportion of elements by mass?

Accepted Answer

Law of Definite Proportions

Question 10

How many atoms are present in $$2.26 g of $$helium (He)? (Atomic mass of He = $$4.00 g/$$mol)

Accepted Answer

$$2.26 \div 4.00 	imes 6.022 	imes 10$$^{23}$$ = 3.40 	imes 10$$^{23}$$ atoms

Question 11

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 12

What is the mass in grams of $$1.1 	imes 10$$^{21}$$ gold (Au) atoms? (Atomic mass of Au = 197.0$ g/mol)

Accepted Answer

$$1.1 	imes 10$$^{21}$$ \div 6.022 	imes 10$$^{23}$$ 	imes 197.0 = 0.36 g$$

Question 13

Which of the following is true about atomic mass unit (amu)?

Accepted Answer

It is equal to one-twelfth the mass of a carbon-12 atom.

Question 14

Which of the following best describes the difference between formula mass and molecular mass?

Accepted Answer

Formula mass is used for ionic compounds, while molecular mass is used for covalent compounds.

Question 15

Which of the following is NOT a physical change?

Accepted Answer

Rusting of iron

Question 16

A chemical reaction involves:

Accepted Answer

The rearrangement of atoms present in the reacting substances to form new chemical combinations.

Question 17

Which of the following is the correct value for Avogadro’s number?

Accepted Answer

$$6.022 	imes 10$$^{23}$$

Question 18

Which of the following statements is true regarding the conservation of mass?

Accepted Answer

Mass is neither created nor destroyed during a chemical reaction.

Question 19

Which of the following is a correct statement about isotopes?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 20

Which of the following is the correct formula to calculate the number of moles ($$n) $$from mass ($$m) $$and molar mass ($$M$$)?

Accepted Answer

$$n = \frac{m}{M}$$

General Chemistry I: Foundations, Atomic Theory, Periodic Table, and Moles

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