when the heat of a reaction is negative which statement is true

HESI A2

HESI A2 Physics

1. When the heat of a reaction is negative, which statement is true?

A. The products have less energy and are less stable.
B. The products have more energy and are more stable.
C. The products have less energy and are more stable.
D. The products have more energy and are less stable.

Correct answer: C

Rationale: When the heat of a reaction is negative, it indicates that the reaction releases energy in the form of heat. This means that the products have lower energy levels compared to the reactants. Lower energy levels are associated with greater stability in chemical systems. Therefore, when the heat of a reaction is negative, the products are more stable due to having less energy than the reactants. Choice A, stating that the products have less energy and are less stable, is incorrect as lower energy levels imply greater stability. Choice B, stating that the products have more energy and are more stable, is incorrect as lower energy levels lead to higher stability. Choice D, stating that the products have more energy and are less stable, is incorrect as lower energy levels are associated with higher stability.

2. Which of the following is a structure found in the upper respiratory tract?

A. Larynx
B. Pharynx
C. Esophagus
D. Trachea

Correct answer: B

Rationale: The pharynx is indeed a structure located in the upper respiratory tract. It acts as a common passageway for both air heading to the lungs and food traveling to the esophagus, making it a vital structure for breathing and swallowing functions. The larynx, trachea, and esophagus are also part of the respiratory and digestive systems but are not specifically located in the upper respiratory tract. The larynx is situated below the pharynx, while the trachea is found below the larynx, and the esophagus is part of the digestive system, not the respiratory tract.

3. A truck driver traveled 925 miles from 8 am Tuesday to 5 pm Wednesday. During that time, he stopped for 30 minutes for lunch and gas at 1 pm Tuesday. He stopped for the night at 7 pm and was back on the road at 5 am. What was his average speed?

A. 42 mph
B. 35 mph
C. 30 mph
D. 50 mph

Correct answer: A

Rationale: To find the average speed, divide the total distance traveled (925 miles) by the total time taken (22 hours). Subtracting the time for the lunch and gas stop (30 minutes) and overnight stop (7 pm to 5 am, 10 hours), we have a total elapsed time of 22 hours. Dividing 925 miles by 22 hours gives an average speed of approximately 42 mph. Choice B, 35 mph, is incorrect because it doesn't account for the total time spent including the stops. Choice C, 30 mph, is incorrect as it underestimates the speed. Choice D, 50 mph, is incorrect as it overestimates the speed.

4. Which element has an atomic mass greater than that of sodium?

A. Boron
B. Oxygen
C. Fluorine
D. Silicon

Correct answer: D

Rationale: Silicon has an atomic mass greater than that of sodium. The atomic mass of silicon is approximately 28.0855 u, whereas the atomic mass of sodium is approximately 22.9898 u. Therefore, silicon has a greater atomic mass compared to sodium. Boron, Oxygen, and Fluorine have atomic masses lower than sodium, making them incorrect choices in this context.

5. During protein synthesis, what process uses an RNA strand to produce a complementary strand of DNA?

A. Transcription
B. Translation
C. Transfer synthesis
D. Codon synthesis

Correct answer: A

Rationale: The correct answer is 'Transcription.' During transcription, an RNA strand is used to produce a complementary strand of DNA. This process is essential for converting the genetic information stored in DNA into RNA. Choice B, 'Translation,' is incorrect as it involves the synthesis of proteins from mRNA. Choice C, 'Transfer synthesis,' is not a recognized term in molecular biology. Choice D, 'Codon synthesis,' is also incorrect as it does not refer to the process of using an RNA strand to produce a complementary DNA strand.