AnswersTX-Chemistry BCumulative Exam

Cumulative Exam — Cumulative exam Answers

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Which statement best describes what makes a base weak?

A
A base is weak when it forms few ions in water.
B
A base is weak when only a little of it is dissolved in water.
C
A base is weak when its concentration is high.
D
A base is weak when it totally forms ions in water.
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A sample of propane (C3H8) has a mass of 0.47 g. The sample is burned in a bomb calorimeter that has a mass of 1.350 kg and a specific heat of 5.82 J/(g • °C). How much energy is released by the reaction if the temperature of the calorimeter rises by 2.87°C?Use .

Question illustration
A
7.85 kJ
B
10.6 kJ
C
22.5 kJ
D
47.9 kJ
43

Consider the diagram.Which postulate of the kinetic-molecular theory best describes the event in the diagram?

Question illustration
A
Most of the volume of a gas is empty space.
B
All collisions between particles are perfectly elastic.
C
There is no force of attraction or repulsion between gas particles.
D
The average kinetic energy of particles depends only on temperature.
44

Ethyne (C2 H2 (g), Hf = 226.77 kJ/mol) undergoes complete combustion in the presence of oxygen to produce carbon dioxide (CO2 (g), Hf = –393.5 kJ/mol ) and water (H2 O(g), Hf = –241.82 kJ/mol) according to the equation below.What is the enthalpy of combustion (per mole) of C2 H2 (g)? Use .

Question illustration
A
–2511.2 kJ/mol
B
–1255.6 kJ/mol
C
–862.1 kJ/mol
D
–431.0 kJ/mol
45

Two cups of coffee, one that is at 10°C and one that is at 20°C, are mixed. Which statement about the temperature of the mixture is correct?

A
There is no kinetic energy transfer so the temperature of the coffee in the warmer cup is the final temperature.
B
The kinetic theory dictates that the temperature of the coffee in the cooler cup is the final temperature.
C
Energy is transferred from faster moving molecules to slower moving molecules, and the result is the average of 15°C.
D
Energy transfer occurs as the molecules collide, and the result is additive; the final temperature is 30°C.
46

Read the table below.Reduction Half-ReactionStandard Reduction Potential (V)Which reactants would lead to a spontaneous reaction?

Question illustration
A
Mn2+ and Al
B
Mn and Al3+
C
Al and Mn
D
Mn2+ and Al3+
47

Why does the presence of lone pair electrons contribute to the polarity of a water molecule?

A
They allow the bonds between oxygen and hydrogen to be single.
B
They increase the partial positive charge on the oxygen atom.
C
They prevent the atoms from forming a linear molecule.
D
They counter the uneven pull on electrons between the atoms.
48

Which contributes to the dissolution of sugar in water?

A
the dissociation of an ionic compound in water
B
a strong pull of water molecules on an ionic compound
C
the dissociation of a polar covalent compound in water
D
a strong pull of water molecules on a polar covalent compound
49

Which of the following is an oxidation-reduction reaction?

A
SO2(g) + H2O(l) H2SO3(aq)
Option A
B
CaCO3(s) CaO(s) + CO2(g)
Option B
C
Ca(OH)2(s) + H2CO3(l) CaCO3(aq) + 2H2O(l)
Option C
D
C6H12O6(s) + 6O2(g) 6CO2(g) + 6H2O(l)
Option D
50

Which statement best explains why different gases effuse at different rates?

A
At a given pressure, gas particles with smaller masses move faster.
B
At a given pressure, gas particles with smaller masses move slower.
C
At a given temperature, gas particles with smaller masses move faster.
D
At a given temperature, gas particles with smaller masses move slower.

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