1.According to the Law of Definite Proportions

Ch 2 Practice Problems

1.According to the law of definite proportions,

A)if the same two elements form two different compounds, they do so in the same ratio.

B)it is not possible for the same two elements to form more than one compound.

C)the ratio of the masses of the elements in a compound is always the same.

D)the total mass after a chemical change is the same as before the change.

2.Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?

A)NH3 and NCl3

B)ZnO and ZnCl2

C)H2O and HI

D)NO and NO2

E)CH4 and CO2

3.How many of the following did Dalton not discuss in his atomic theory? I. isotopes II. ions III. protons IV. neutrons V. electrons

A)1

B)2

C)3

D)4

E)5

4.When 3.0 L of hydrogen gas (H2) reacts with 1.0 L of nitrogen gas (N2), 2.0 L of gaseous product is formed. All volumes of gases are measured at the same temperature and pressure. What is the formula of the product?

A)N3H

B)NH3

C)NH4

D)NH

E)N2H3

5.Which one of the following statements about atomic structure is false?

A)The electrons occupy a very large volume compared to the nucleus.

B)Almost all of the mass of the atom is concentrated in the nucleus.

C)The protons and neutrons in the nucleus are very tightly packed.

D)The number of protons and the number of neutrons are always the same in the neutral atom.

6.Which of the experiments listed below did not provide the information stated about the nature of the atom?

A)The Rutherford experiment proved that the Thomson "plum pudding" model of the atom was essentially correct.

B)The Rutherford experiment determined the charge on the nucleus.

C)Millikan's oil-drop experiment showed that the charge on any particle was a simple multiple of the charge on the electron.

D)The cathode-ray tube proved that electrons have a negative charge.

7.Which of the following atomic symbols is incorrect?

A)2010Ne

B)3216S

C)2814Si

D)4020Ca

E)128C

8.The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus

A)75 protons, 75 neutrons.

B)75 protons, 130 neutrons.

C)130 protons, 75 neutrons.

D)75 protons, 110 neutrons.

E)not enough information is given.

9.Which of the following statements is(are) true?

I. / O and F have the same number of neutrons.
II. / C and N are isotopes of each other because their mass numbers are the same.
III. / O2– has the same number of electrons as Ne.

A)I only

B)II only

C)III only

D)I and II only

E)I and III only

10.Which among the following represent a set of isotopes? Atomic nuclei containing

I. / 20 protons and 20 neutrons.
II. / 21 protons and 19 neutrons.
III. / 22 neutrons and 18 protons.
IV. / 20 protons and 22 neutrons.
V. / 21 protons and 20 neutrons.

A)I, II, III

B)III, IV

C)I, V

D)I, IV and II, V

E)No isotopes are indicated.

11.How many protons, neutrons, and electrons does the atom 33S have?

A)16 protons, 16 neutrons, 33 electrons

B)17 protons, 17 neutrons, 16 electrons

C)16 protons, 16 neutrons, 16 electrons

D)17 protons, 16 neutrons, 17 electrons

E)16 protons, 17 neutrons, 16 electrons

12.An ion is formed

I. / by either adding protons to or subtracting protons from the atom.
II. / by either adding electrons to or subtracting electrons from the atom.
III. / by either adding neutrons to or subtracting neutrons from the atom.

A)Only I is true.

B)Only II is true.

C)Only III is true.

D)All of the statements are true.

E)Two of the statements are true.

13.Which is the symbol for the isotope of nitrogen that has 7 protons and 8 neutrons?

14.Which of the following represents a pair of isotopes?

A)146C, 147N

B)11H, 21H

C)147N, 158O

D)C, C60

E)3115P, 3115P3-

15.Which of the following statements is(are) true?

I. / The number of protons is the same for all neutral atoms of an element.
II. / The number of electrons is the same for all neutral atoms of an element.
III. / The number of neutrons is the same for all neutral atoms of an element.

A)I, II, and III are all true.

B)Only I and II are true.

C)Only II and III are true.

D)Only I and III are true.

E)I, II, and III are all false.

16.The ion 14N3- has

A)7 protons, 7 neutrons, 7 electrons

B)7 protons, 7 neutrons, 4 electrons

C)7 protons, 7 neutrons, 3 electrons

D)7 protons, 7 neutrons, 10 electrons

E)7 protons, 14 neutrons, 7 electrons

17.The ion 127I- has

A)53 protons, 74 neutrons, 54 electrons

B)53 protons, 74 neutrons, 53 electrons

C)53 protons, 74 neutrons, 52 electrons

D)53 protons, 127 neutrons, 54 electrons

E)53 protons, 53 neutrons, 53 electrons

18.An element's most stable ion forms an ionic compound with chlorine having the formula XCl2. If the mass number of the ion is 40 and it has 18 electrons, what is the element and how many neutrons does it have?

A)Ar, 22 neutrons

B)Ar, 24 neutrons

C)S, 24 neutrons

D)Ca, 20 neutrons

E)K, 19 neutrons

19.Which element does not belong to the family or classification indicated?

A)I, halogen

B)Kr, noble gas

C)Co, transition metal

D)K, alkali metal

E)As, lanthanides

20.Which are alkaline earth halides?

A)NaI, KBr, LiF

B)CaF2, MgBr2, SrI2

C)PbI2, PbBr2, CdF2

D)MgO, MgS, CaO

E)Al2O3, In2O3, Ga2S3

21.Select the group of symbols that would correctly complete the following statements, respectively.

___ is the heaviest noble gas.

___ is the transition metal that has 24 electrons as a 3+ ion.

___ is the halogen in the third period.

___ is the alkaline earth metal that has 18 electrons as a stable ion.

A)Rn, Cr, Br, Ca

B)Ra, Co, Cl, K

C)Rn, Co, Cl, Ca

D)Ra, Sc, Br, K

22.______form ions with a 2+ charge when they react with nonmetals.

A)Alkali metals

B)Alkaline earth metals

C)Halogens

D)Noble gases

E)None of these choices

23.Which of the following formulas is not correct?

A)MgSO3

B)Ba(NO3)2

C)NaS

D)KCl

E)NH4I

24.Which of the following is not the correct chemical formula for the compound named?

NaOH / sodium hydroxide

Fe3SO4 / iron(III) sulfate

HCl / hydrogen chloride

CaBr2 / calcium bromide

Mg3N2 / magnesium nitride

25.Which of the following is not the correct name for the formula given?

Fe2O3 / iron(III) oxide

PBr5 / phosphorus pentabromide

CoO / cobalt(II) oxide

CaSO4 / calcium sulfite

HClO / hypochlorous acid

26.Which is not the correct chemical formula for the compound named?

lithium phosphate / Li3PO4

copper(II) oxide / CuO

magnesium carbonate / MgCO3

ammonium sulfide / NH4S

barium nitrate / Ba(NO3)2

27.What is the correct formula for aluminum carbonate?

A)AlCO3

B)Al2(CO3)3

C)Al3(CO3)2

D)Al2CO3

E)Al3CO3

28.Which of the following is not the correct chemical formula for the compound named?

Li2O / lithium oxide

Fe3PO4 / iron(III) phosphate

HF / hydrogen fluoride

BaCl2 / barium chloride

Mg3N2 / magnesium oxide

29.Which formula is not correct?

A)NH4C2H3O2

B)CaO

C)Ba(NO3)2

D)ZnBr

E)NaF

30.What is the correct formula for chromium(VI) oxide?

A)CrO6

B)Cr6O

C)CrO3

D)Cr2O3

E)CrO2

31.Which of the following is not the correct name for the formula given?

Fe2O3 / iron(III) oxide

PCl5 / phosphorus pentachoride

CoO / cobalt(II) oxide

BaSO3 / barium sulfate

HClO / hypochlorous acid

32.Which of the following is not the correct chemical formula for the compound named?

Al(OH)2 / aluminum hydroxide

LiSCN / lithium thiocyanate

Fe2O3 / iron(III) oxide

BaS / barium sulfide

Mg(C2H3O2)2 / magnesium acetate

33.Which is the correct formula for copper(I) sulfide?

A)CuS

B)Cu2S

C)CuS2

D)Cu2S2

E)Cu2S3

34.Complete the following table.

Symbol / Number of Protons / Number of Neutrons / Number of Electrons / Net Charge
31 / 38 / 3+
52 / 75 / 54
/ 29 / 2+

35.Complete the following table.

Symbol / 56Fe2+
Number of protons / 35
Number of neutrons / 45
Number of electrons
Atomic number
Mass number
Net charge / 1-

Name the following compounds:

36.Al2(SO4)3

37.NH4NO3

38.NaH

39.K2Cr2O7

40.CCl4

41.AgCl

42.CaSO4

43.HNO3

44.N2O3

45.SnI2

Write the formula for:

46.sodium dichromate

47.iron(III) oxide

48.dinitrogen trioxide

49.cobalt(II) chloride

50.aluminum hydroxide

51.hydrosulfuric acid

52.sulfurous acid

53.nitric acid

54.phosphoric acid

55.acetic acid

56.Write the chemical formulas for the following compounds or ions.

a) nitrate ion / ______
b) aluminum oxide / ______
c) ammonium ion / ______
d) perchloric acid / ______
e) copper(II) bromide / ______

57.Write the names of the following compounds:

a) FeSO4 / ______
b) NaC2H3O2 / ______
c) KNO2 / ______
d) Ca(OH)2 / ______
e) NiCO3 / ______

Answers

1. / C / 11. / E / 21. / C / 31. / D
2. / D / 12. / B / 22. / B / 32. / A
3. / E / 13. / C / 23. / C / 33. / B
4. / B / 14. / B / 24. / B
5. / D / 15. / B / 25. / D
6. / A / 16. / D / 26. / D
7. / E / 17. / A / 27. / B
8. / D / 18. / D / 28. / B
9. / C / 19. / E / 29. / D
10. / D / 20. / B / 30. / C

34.

Symbol / Number of Protons / Number of Neutrons / Number of Electrons / Net Charge
/ 82 / 124 / 82 / 0
/ 31 / 38 / 28 / 3+
/ 52 / 75 / 54 / 2–
/ 25 / 29 / 23 / 2+

35.

Symbol / 56Fe2+ / 80Br-
Number of protons / 26 / 35
Number of neutrons / 30 / 45
Number of electrons / 24 / 36
Atomic number / 26 / 35
Mass number / 56 / 80
Net charge / 2+ / 1-

36. aluminum sulfate

37. ammonium nitrate

38. sodium hydride

39. potassium dichromate

40. carbon tetrachloride

41. silver chloride

42. calcium sulfate

43. nitric acid

44. dinitrogen trioxide

45. tin(II) iodide

46. Na2Cr2O7

47. Fe2O3

48. N2O3

49. CoCl2

50. Al(OH)3

51. H2S

52. H2SO3

53. HNO3

54. H3PO4

55. HC2H3O2

56. a. NO3– b. Al2O3 c. NH4+ d. HClO4 e. CuBr2

57. a. iron(II) sulfate b. sodium acetate c. potassium nitrite d. calcium hydroxide e. nickel(II) carbonate