Free Printable Most Missed/Difficult Chemistry Regents Questions

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Most Missed/Difficult Chemistry Regents Questions

Total questions: 98

Worksheet time: 3hrs 23mins

Name

Class

Date

Systems in nature tend to undergo changes toward

lower energy and lower entropy

higher energy and lower entropy

lower energy and higher entropy

higher energy and higher entropy

At STP, solid carbon can exist as graphite or diamond. These two forms of carbon have

the same properties and same crystal structure

the same properties and different crystal structure

different properties and same crystal structure

different properties and different crystal structure

Compared to a 0.1 M aqueous solution of NaCl, a 0.8 M aqueous solution of NaCl has a

higher boiling point and a higher freezing point

higher boiling point and a lower freezing point

lower boiling point and a higher freezing point

lower boiling point and a lower freezing point

Which equation represents a fusion reaction?

Which symbol represents a particle that hast he same total number of electrons as $S^{-2}$ ?

$O^{-2}$

$Si$

$Se^{-2}$

$Ar$

Which molecule contains a non-polar covalent bond?

According to reference table G, which substance forms an unsaturated solution when 80 grams of the substance is dissolved into 100 grams water at 10ºC?

$KI$

$KNO_3$

$NaNO_3$

$NaCl$

Given the balanced ionic equation:

$Zn_{\left(s\right)}\ +\ Cu_{\left(aq\right)}^{+2}\ \to\ Zn_{\left(aq\right)}^{+2}\ +\ Cu_{\left(s\right)}$

Which equation represents the oxidation half reaction?

$Zn_{\left(s\right)}\ +\ 2e^-\ \to Zn_{\left(aq\right)}^{+2}$

$Zn_{\left(s\right)}\ \to Zn_{\left(aq\right)}^{+2}\ +\ 2e^-$

$Cu_{\left(aq\right)}^{+2}\ \to Cu_{\left(s\right)}\ +\ 2e^-$

$Cu_{\left(aq\right)\ }^{+2}+\ 2e^-\ \to Cu_{\left(s\right)}$

What is the half life of sodium-25 if 1.00 grams of a 16.00 gram sample

remains unchanged after 237 seconds?

47.4 sec

59.3 sec

79.0 sec

118 sec

10.

Proposed models of the atom:

Model A: protons in nucleus, electrons in specific shells

Model B: protons in nucleus, electrons in regions of most probably location

Model C: protons dispersed throughout the atom, electrons in specific shells

Model D: protons dispersed throughout the atom, electrons in regions of most probably location

Which model correctly describes the locations of protons and electrons in the

wave-mechanical model of the atom?

11.

Ethyl ethanoate is used as a solvent for varnishes and in the manufacture of artificial leather. The formula represents a molecule of ethyl ethanoate.

Write the name of the class of organic compounds to which this compound belongs.

(a)

12.

What is the IUPAC name for the compound that has a condensed structure of CH₃CH₂CH₂CHO?

butanol

butanal

propanol

propanal

13.

Atoms of different isotopes of the same element differ in their total number of

Electrons

Neutrons

Protons

Valence Electrons

14.

Which statement correctly describes two forms of oxygen, O₂ and O₃?

they have identical molecular structures and identical properties

they have identical molecular structures and different properties

they have different molecular structures and identical properties

they have different molecular structures and different properties

15.

Which formula represents a hydrocarbon?

CH₃CH₂CH₂CHO

CH₃CH₂CH₂CH₃

CH₃CH₂CH₂COOH

CH₃CH₂COOCH₃

16.

Which balanced equation represents a redox reaction?

$AgNO_{3\ }\ +\ NaCl\ \to AgCl\ +\ NaNO_3$

$BaCl_2+K_2CO_3\ \to BaCO_3+2KCl$

$CuO\ +\ CO\ \to Cu\ +\ CO_2$

$HCl\ +\ KOH\ \to KCl\ +H_2O$

17.

In the wave-mechanical model, an orbital is a region of space in an atom where there is

a high probability of finding an electron

a circular path in which electrons are found

a high probability of finding a neutron

a circular path in which neutrons are found

18.

What is the charge of the nucleus in an atom of oxygen-17?

-2

+17

19.

Helium is most likely to behave as an ideal gas when it is under

high pressure and high temperature

low pressure and high temperature

high pressure and low temperature

low pressure and low temperature

20.

In a nuclear fusion reaction, the mass of the products is

less than the mass of the reactants because some of the mass has been converted to energy.

less than the mass of the reactants because some of the energy has been converted to mass.

more than the mass of the reactants because some of the mass has been converted to energy.

more than the mass of the reactants because some of the energy has been converted to mass.

21.

Which pair of formulas represents two compounds that are electrolytes?

HCl and CH₃OH

HCl and NaOH

C₅H₁₂ and CH₃OH

C₅H₁₂ and NaOH

22.

Which compound could serve as a reactant in neutralization reaction?

NaCl

KOH

CH₃OH

CH₂CHO

23.

How many electrons are contained in an Au³⁺ ion?

197

24.

Using your knowledge of chemistry and the information in Reference Table H, which statement concerning propanone and water at 50°C is true?

Propanone has a higher vapor pressure and stronger intermolecular forces than water.

Propanone has a higher vapor pressure and weaker intermolecular forces than water.

Propanone has a lower vapor pressure and stronger intermolecular forces than water.

Propanone has a lower vapor pressure and weaker intermolecular forces than water.

25.

Which type of molecule is CF₄?

polar, with a symmetrical distribution of charge

polar, with an asymmetrical distribution of charge

nonpolar, with a symmetrical distribution of charge

nonpolar, with an asymmetrical distribution of charge

26.

Conductivity in a metal results from the metal atoms having

high electronegativity

high ionization energy

highly mobile protons in the nucleus

highly mobile electrons in the valence shell

27.

Which of these elements has the least attraction for electrons in a chemical bond?

oxygen

fluorine

nitrogen

chlorine

28.

Given the reaction for the corrosion of aluminum:

4 Al + 3 O₂ → 2 Al₂O₃

Which half-reaction correctly represents the oxidation that occurs?

4Al + 12e− → 4Al³⁺

3O₂ + 12e− → 6O²⁻

4Al → 4Al³⁺ + 12e−

3O₂ → 6O²⁻ + 12e−

29.

Given the reaction shown. This reaction is an example of

fermentation

saponification

addition

esterification

30.

Which equation represents a fusion reaction?

31.

The kinetic molecular theory assumes that the particles of an ideal gas

are in random, constant, straight-line motion

are arranged in a regular geometric pattern

have strong attractive forces between them

have collisions that result in the system lowing energy

32.

Where does oxidation occur in an electrochemical cell?

at the cathode in both an electrolytic and a voltaic cell

at the cathode in an electrolytic cell and at the anode in a voltaic cell

at the anode in both an electrolytic cell and a voltaic cell

at the anode in an electrolytic cell and at the cathode in a voltaic cell

33.

What is the formula of titanium(II) oxide?

TiO

TiO₂

Ti₂O

Ti₂O₃

34.

A 1.0-gram piece of zinc reacts with 5 milliliters of HCl_(AQ). Which of these conditions of concentration and temperature would produce the greatest rate of reaction?

1.0 M HCl_(AQ) at 20.^oC

2.0 M HCl_(AQ) at 20.^oC

1.0 M HCl_(AQ) at 40_.^oC

2.0 M HCl_(AQ) at 40.^oC

35.

Which equation represents a transmutation reaction?

36.

As a chlorine atom becomes a negative ion, the atom

gains an electron & its radius increases

loses an electron & its radius increases

gains an electron & its radius decreases

loses an electron & its radius decreases

37.

Given the balanced equation:

$KNO_{3\left(s\right)}\ +\ 34.98kJ\ \to K_{\left(aq\right)}^{+1}\ +NO_{\left(aq\right)}^{-1}$

Which statement best describes this process?

It is endothermic and entropy increases

It is exothermic and entropy increases

It is endothermic and entropy decreases

It is exothermic and entropy decreases

38.

A saturated solution of NaNO₃ is prepared at 60.^oC using 100. grams of water. As this solution is cooled to 10.^oC, NaNO₃ precipitates (settles) out of the solution. The resulting solution is saturated. Approximately how many grams of NaNO₃ settled out of the original solution?

46 g

61 g

85 g

126 g

39.

A student tested a 0.1 M aqueous solution and made the following three observations:

1-Conducts electricity

2-Turns blue litmus red

3-Reacts with Zn(S) to produce gas bubbles

Which compound could be the solute in this solution?

CH₃OH

LiBr

HBr

LiOH

40.

Given the table that shows students’ examples of proposed models of the atom:

Which model correctly describes the locations of protons and electrons in the wave-mechanical model of the atom?

41.

Which reactants form the salt CaSO_4(S) in a neutralization reaction?

H₂S_(G) + Ca(ClO₄)_2(S)

H₂SO_3(AQ) + Ca(NO₃)_2(AQ)

H₂SO_4(AQ) + Ca(OH)_2(AQ)

SO_2(G) + CaO_(S)

42.

A metal, M forms an oxide compound with the general formula M₂O. In which group on the Periodic Table could metal M be found?

Group 1

Group 2

Group 15

Group 17

43.

What volume of 0.500 M HNO_3(AQ) must completely react to neutralize 100.0 mL of 0.100 M KOH_(AQ)

10.0 mL

20.0 mL

50.0 mL

500. mL

44.

Given the balanced equation with an unknown compound “X”:

C₆H₁₂O_6(AQ) → 2 X + 2 CO_2(G)

Which compound is represented by X ?

CH₃OH_(AQ)

CH₂(OH)_4(AQ)

CH₃CH₂OH_(AQ)

CH₂OHCH₂OH_(AQ)

45.

What is the total number of electrons shared in the bonds between the carbon atoms in a molecule of:

$\text{}H-C\equiv C-H$

46.

Which changes occur as a cadmium atom, Cd, becomes a cadmium ion, Cd²⁺?

The Cd atom

gains two electrons and its radius decreases.

loses two electrons and its radius decreases.

gains two electrons and its radius increases.

loses two electrons and its radius increases.

47.

The compounds CH₃OCH₃ & CH₃CH₂OH are isomers of each other.

These compounds must have the same

density

reactivity

melting point

molecular formula

48.

Which process occurs at the anode in an electrochemical cell?

loss of protons

loss of electrons

gain of protons

gain of electrons

49.

Which ion is the only negative ion present in an aqueous solution of an Arrhenius base?

Hydride ion

Hydrogen ion

Hydronium ion

Hydroxide ion

50.

A dilute, aqueous potassium nitrate solution is best qualified as a

homogeneous compound

heterogeneous compound

homogeneous mixture

heterogeneous mixture

51.

Which energy conversion occurs during the operation of a voltaic cell?

Chemical energy is spontaneously converted to electrical energy.

Chemical energy is converted to electrical energy only when an external power source is provided.

Electrical energy is spontaneously converted to chemical energy

Electrical energy is converted to chemical energy only when an external power source is provided.

52.

Which electron configuration could represent a strontium atom in an excited state?

2−8−18−7−1

2−8−18−7−3

2−8−18−8−1

2−8−18−8−2

53.

At STP, which element is brittle and not a conductor of electricity?

54.

Compared to an electron in the 1st electron shell of an atom, an electron in the 3rd shell of the same atom as

less mass

less energy

more mass

more energy

55.

At which Celsius temperature does lead change from a solid to a liquid?

874

601

327

56.

Which radioisotope is used in medicine to diagnose thyroid disorders?

cobalt-60

iodine-131

phosphorus-32

uranium-238

57.

What is the total charge on the nucleus of a carbon atom?

-6

+12

58.

For a given reaction, adding a catalyst increases the rate of the reaction by

providing an alternate reaction pathway that has a higher activation energy

providing an alternate reaction pathway that has a lower activation energy

using the same reaction pathway and increasing the activation energy

using the same reaction pathway and decreasing the activation energy

59.

An atom in the ground state contains a total of 5 electrons, 5 protons, and 5 neutrons. Draw the Lewis electron-dot diagram that represents this atom, using X as the symbol of the element.

60.

In the early 1900’s, experiments were conducted to determine the structure of the atom. One of these experiments involved bombarding gold foil with alpha particles. Most alpha particles passed directly through the foil. Some, however, were deflected at various angles. Based on this alpha particle experiment, state two conclusions that were made concerning the structure of an atom.

4 lines

61.

Draw the Lewis electron-dot diagram for F- ion.

62.

Show a correct set-up and calculate the average atomic mass of neon.

Ne-20 Atomic Mass: 19.99g, Percent Natural Abundance 90.9%

Ne-21 Atomic Mass: 20.99g, Percent Natural Abundance 0.3%

Ne-22 Atomic Mass: 21.99g, Percent Natural Abundance 8.8%

63.

Napthalene, a nonpolar substance that sublimes at room temperature, can be used to protect wool clothes from being eaten by moths.

Explain, in terms of intermolecular forces, why napthalene sublimes.

4 lines

64.

Napthalene, a nonpolar substance that sublimes at room temperature, can be used to protect wool clothes from being eaten by moths.

Explain why naphthalene is not expected to dissolve in water.

4 lines

65.

A weather balloon has a volume of 52.5 liters at a temperature of 295 K. the balloon is released and rises to an altitude where the temperature is 252 K. The original pressure was 100.8 kPa and the pressure at the higher altitude is 45.6 kPa. Assume the balloon does not burst calculate the volume of the balloon at the higher altitude.

66.

A student titrates 60.0 mL of HNO_3(AQ) with 0.30 M NaOH_(AQ). Phenolphthalein is used as the indicator. After adding 42.2 mL of NaOH_(AQ), a color change remains for 25 seconds, and the student stops the titration. Calculate the molarity of the of HNO_3(AQ),

67.

Which atom has the greatest attraction for the electrons in a chemical bond?

hydrogen

oxygen

silicon

sulfur

68.

A 10.0 gram sample of nitrogen is at STP. Which property will increase when the sample is cooled to 72K at standard pressure

mass

volume

density

temperature

69.

A 5.0-gram sample of Fe(s) is to be placed in 100. milliliters of HCl(aq). Which changes will result in the fastest rate of reaction.

Increasing the surface area of Fe(s) and increasing the concentration of HCl(aq)

Increasing the surface area of Fe(s) and decreasing the concentration of HCl(aq)

Decreasing the surface area of Fe(s) and decreasing the concentration of HCl(aq)

Decreasing the surface area of Fe(s) and increasing the concentration of HCl(aq)

70.

At STP, which sample contains the same number of molecules as 3.0L of H_2(g)?

1.5L of NH_3(g)

2.0L of CO_2(g)

3.0L of CH_4(g)

6.0L of N_2(g)

71.

A sample of water is boiling as heat is added at a constant rate. Which statement describes the potential energy and the average kinetic energy of the water molecules in this sample?

The potential energy decreases and the average kinetic energy remains the same

The potential energy decreases and the average kinetic energy increases

The potential energy increases and the average kinetic energy remains the same

The potential energy increases and the average kinetic energy increases

72.

What is the number of electrons shared in the multiple carbon-carbon bond in one molecule of 1 -pentyne?

73.

One acid-base theory defines an acid as an

H+ donor

H+ acceptor

H- donor

H- acceptor

74.

Which change occurs during a nuclear fission reaction?

Covalent bonds are converted to ionic bonds.

Isotopes are converted to isomers.

Temperature is converted to mass.

Matter is converted to energy

75.

What is the chemical formula for lead (IV) oxide?

PbO₂

PbO₄

Pb₂O

Pb₄O

76.

What is the percent composition by mass of nitrogen in (NH₄)₂CO₃ (gram-formula mass = 96. 0 g/mol)?

14.6%

29.2%

58.4%

87.5%

77.

Which aqueous solution has the highest boiling point at standard pressure?

1.0M KCl _(aq)

1.0M CaCl_{2 (aq)}

2.0M KCl _(aq)

2.0M CaCl_{2 (aq)}

78.

Which volume of 0. 600 M H₂SO_4(aq) exactly neutralizes 100. milliliters of 0. 300 M Ba(OH)_2(aq)?

25.0 mL

50.0 mL

100. mL

200. mL

79.

Which type of organic reaction produces both water and carbon dioxide?

addition

combustion

esterification

fermentation

80.

At standard pressure, water has unusual properties that are due to both its molecular

structure and intermolecular forces. For example, although most liquids contract when they

freeze, water expands, making ice less dense than liquid water. Water has a much higher

boiling point than most other molecular compounds having a similar gram-formula mass.

State the type of intermolecular force responsible for the unusual boiling point of H₂O(ℓ) at standard pressure.

(a)

81.

Draw a lewis electron dot diagram for a chloride ion, Cl^-

82.

At 1023 K and 1 atm, a 3.00-gram sample of SnO_2(s)(gram-formula mass = 151 g/mol)

reacts with hydrogen gas to produce tin and water, as shown in the balanced equation

below.

$SnO_{2\left(s\right)}\ +\ 2H_{2\left(g\right)}\ \to Sn_{\left(l\right)}\ +2H_2O_{\left(g\right)}$

Determine the number of moles of Sn_(ℓ)produced when 4.0 moles of H_2(g)is

completely consumed.

83.

Potassium phosphate, K₃PO₄, is a source of dietary potassium found in a popular

cereal. According to the Nutrition-Facts label shown on the boxes of this brand of cereal, the accepted value for a one-cup serving of this cereal is 170. milligrams of potassium.The minimum daily requirement of potassium is 3500 milligrams for an adult human.

Identify two types of chemical bonding in the source of dietary potassium in this cereal.

(a)

84.

Fireworks that contain metallic salts such as sodium, strontium, and barium can

generate bright colors. A technician investigates what colors are produced by the metallic salts by performing flame tests. During a flame test, a metallic salt is heated in the flame of a gas burner. Each metallic salt emits a characteristic colored light in the flame.

Explain, in terms of electrons, how a strontium salt emits colored light.

(a)

85.

State the purpose of the salt bridge in the voltaic cell.

(a)

86.

Complete and balance the half-reaction for the oxidation of Zn(s) that occurs in the voltaic cell

87.

Given the balanced equation for dissolving NH₄Cl(s) in water

$NH_4Cl\ +\ H_2O\ \rightarrow\ NH_{4\left(aq\right)}^+\ +\ Cl_{\left(aq\right)}^-$

A student is holding a test tube containing 5.0 milliliters of water. When a sample of NH₄Cl is placed in the

test tube, the test tube feels colder to the student’s hand. Describe the direction of heat flow between the test

tube and the hand.

Also, using the representation of a chloride ion, Cl^-(aq) in the aqueous solution, draw at least two water

molecules around it, showing the correct orientation of each water molecule next to the ion.

88.

Balance the equation using the smallest whole-number coefficients

(a) NH₃(g) + (b) O₂(g) $\rightarrow$ (c) NO(g) + (d) H₂O(g) + heat

Choose from the below words

89.

At STP, the element oxygen can exist as either O₂or O₃ molecules. These two forms of the element have

the same chemical and physical properties

the same chemical properties and different physical properties

different chemical properties and the same physical properties

different chemical and physical properties

90.

Which substance is an electrolyte?

CH₃OH

C₆H₁₂O₆

H₂O

KOH

91.

Which balanced equation represents nuclear fusion

92.

Write the reduction half-reaction for the following equation:

93.

Draw the structural formula for the product of the reaction shown

94.

Given the reaction at dynamic equilibrium

$2NO_{2\left(g\right)}+\ 7H_{2\left(g\right)}\leftrightarrow\ 2NH_{3\left(g\right)\ }+\ 2H_2O_{\left(g\right)}+\ 1127\ kJ$

Draw a potential energy diagram for the forward reaction.

95.

Given the reaction at dynamic equilibrium

2NO_2(g)+ 7H_2(g)↔ 2NH_3(g) + 2H₂O_(g)+ 1127 kJ

Explain in terms of LeChatelier's principle why the concentration of NH_3(g)decreases when the temperature of the equilibrium system increases

4 lines

96.

Given the reaction between butane and chlorine gas:

$C_4H_{10}\ +\ Cl_{2\left(g\right)}\rightarrow C_4H_8Cl\ +\ HCl$

What type of chemical reaction is represented by this equation?

4 lines

97.

Given samples of water:

Sample 1: 100. grams of water at 20.°C

Sample 2: 200. grams of water at 20.°C

Compared to sample 1, sample 2 contains

molecules with a lower average kinetic energy

molecules with a lower average velocity

less heat energy

more heat energy

98.

What is the amount of heat required to melt 43 grams of solid magnesium oxide at its melting point? The heat of fusion is 1.9x10³ j/g

2.3 x 10^-2J

4.4 x 10⁴ J

8.2 x 10⁴ J

3.4 x 10⁵ J

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Most Missed/Difficult Chemistry Regents Questions

Total questions: 98

Worksheet time: 3hrs 23mins

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