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

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

Question 1

Which law states that mass is neither created nor destroyed in a chemical reaction?

Accepted Answer

Law of Conservation of Mass

Question 2

A sample of magnesium reacts with oxygen to form magnesium oxide. If 24.3 g of magnesium reacts with 16.0 g of oxygen, what is the total mass of magnesium oxide formed?

Accepted Answer

$$40.3\ \mathrm{g}$$

Question 3

Which of the following best describes the Law of Definite Proportions?

Accepted Answer

A compound always contains the same elements in the same proportion by mass.

Question 4

Which postulate of Dalton’s Atomic Theory was later proven incorrect?

Accepted Answer

Atoms of a given element are identical in mass and properties.

Question 5

Which subatomic particle has a relative charge of $$+1$$ and a mass of approximately $$1\ \mathrm{amu}$$?

Accepted Answer

Proton

Question 6

An isotope of carbon is represented as $$^{14}_{6}\mathrm{C}. $$How many neutrons does this isotope have?

Accepted Answer

$$8$$

Question 7

Which instrument is commonly used to measure the masses of atoms and the percent abundances of isotopes?

Accepted Answer

Mass spectrometer

Question 8

Which element is defined by the atomic number $$Z = 17$$?

Accepted Answer

Chlorine

Question 9

Which group on the periodic table contains the noble gases?

Accepted Answer

Group 18

Question 10

A sample contains $$3.01 	imes 10$$^{23}$$ atoms of silver. How many moles of silver are present?

Accepted Answer

$$0.50$$ moles

Question 11

Which of the following is a metalloid?

Accepted Answer

Silicon

Question 12

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

Accepted Answer

$$18.02\ \mathrm{g/mol}$$

Question 13

Which of the following ions is a cation?

Accepted Answer

$$\mathrm{Na}^+$$

Question 14

How many protons, neutrons, and electrons are in $$^{23}_{11}\mathrm{Na}^+$$?

Accepted Answer

11 protons, 12 neutrons, 10 electrons

Question 15

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 16

Calculate the atomic mass of chlorine if $$^{35}\mathrm{Cl} ($$mass = $$34.97\ \mathrm{amu}$$, abundance = $$75.78\%) $$and $$^{37}\mathrm{Cl} ($$mass = $$36.97\ \mathrm{amu}$$, abundance = $$24.22\%) $$are present.

Accepted Answer

$$35.45\ \mathrm{amu}$$

Question 17

Which element is a transition metal?

Accepted Answer

Iron

Question 18

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

Accepted Answer

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

Question 19

Which of the following best describes the Periodic Law?

Accepted Answer

The properties of elements are periodic functions of their atomic numbers.

Question 20

A sample contains $$10.0\ \mathrm{g} of $$calcium ($$\mathrm{Ca}$$, molar mass $$= 40.08\ \mathrm{g/mol}). $$How many moles of calcium are present?

Accepted Answer

$$0.250$$ moles

Chapter 2 Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard