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Question (41)

QN0035864

Which of the following changes would most directly indicate that a reaction is exothermic?

(A) Temperature of the reaction mixture decreases
(B) Temperature of the reaction mixture increases
(C) No change in temperature
(D) Only the volume decreases

Correct Answer: B

Explanation:

An exothermic reaction releases heat, which can cause the temperature of the reaction mixture to increase.

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Question (42)

QN0035865

Respiration is considered an exothermic process because

(A) glucose absorbs energy from oxygen
(B) glucose combines with oxygen and releases energy
(C) carbon dioxide absorbs all the energy
(D) water decomposes to glucose

Correct Answer: B

Explanation:

During respiration, glucose combines with oxygen and produces carbon dioxide, water and energy.

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Question (43)

QN0035866

In the respiration equation C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy, the total number of oxygen atoms on the reactant side is

(A) 6
(B) 12
(C) 18
(D) 24

Correct Answer: C

Explanation:

Glucose contributes 6 oxygen atoms and 6O₂ contributes 12 oxygen atoms. Total = 18 oxygen atoms.

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Question (44)

QN0035867

The equation C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O is balanced because the number of hydrogen atoms on both sides is

(A) 6
(B) 8
(C) 10
(D) 12

Correct Answer: D

Explanation:

Glucose contains 12 hydrogen atoms and 6H₂O also contains 12 hydrogen atoms.

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Question (45)

QN0035868

An iron object is left exposed to moist air and develops a reddish-brown coating. This process is

(A) rancidity
(B) corrosion
(C) decomposition
(D) precipitation

Correct Answer: B

Explanation:

Rusting of iron is a common example of corrosion.

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Question (46)

QN0035869

A metal article is protected from corrosion by applying paint. The main reason is that paint

(A) increases the reactivity of the metal
(B) prevents contact with substances such as moisture and air
(C) converts the metal into a salt
(D) decomposes the metal

Correct Answer: B

Explanation:

Paint forms a protective layer that prevents the metal from coming into contact with moisture and other substances that cause corrosion.

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Question (47)

QN0035870

A food packet containing fats and oils is flushed with nitrogen. If oxidation is reduced, which problem is being prevented?

(A) Corrosion
(B) Rancidity
(C) Precipitation
(D) Thermal decomposition

Correct Answer: B

Explanation:

Oxidation of fats and oils causes rancidity, which changes their smell and taste. Nitrogen reduces contact with oxygen.

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Question (48)

QN0035871

Three identical samples of an oily food are stored under different conditions: P in open air, Q in an airtight container, and R in a packet flushed with nitrogen. Which sample is expected to have the greatest protection from oxidation based on the chapter?

(A) P only
(B) Q only
(C) R only
(D) P and Q equally

Correct Answer: C

Explanation:

Nitrogen flushing reduces the contact of the food with oxygen. The chapter specifically mentions nitrogen flushing as a method used to prevent oxidation of chips.

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Question (41)

Which of the following changes would most directly indicate that a reaction is exothermic?

Explanation:

Link:

Question (42)

Respiration is considered an exothermic process because

Explanation:

Link:

Question (43)

In the respiration equation C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy, the total number of oxygen atoms on the reactant side is

Explanation:

Link:

Question (44)

The equation C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O is balanced because the number of hydrogen atoms on both sides is

Explanation:

Link:

Question (45)

An iron object is left exposed to moist air and develops a reddish-brown coating. This process is

Explanation:

Link:

Question (46)

A metal article is protected from corrosion by applying paint. The main reason is that paint

Explanation:

Link:

Question (47)

A food packet containing fats and oils is flushed with nitrogen. If oxidation is reduced, which problem is being prevented?

Explanation:

Link:

Question (48)

Three identical samples of an oily food are stored under different conditions: P in open air, Q in an airtight container, and R in a packet flushed with nitrogen. Which sample is expected to have the greatest protection from oxidation based on the chapter?

Explanation:

Link:

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