what is the difference between the atomic number and the mass number of an atom

ATI TEAS 7

ati teas 7 science

1. What is the difference between the atomic number and the mass number of an atom?

A. The atomic number is the number of protons in the nucleus, while the mass number is the total number of protons and neutrons in the nucleus.
B. The atomic number is the number of electrons in an atom, while the mass number is the total number of protons and neutrons in the nucleus.
C. The atomic number is the number of neutrons in the nucleus, while the mass number is the total number of protons and electrons in an atom.
D. The atomic number is the number of protons and neutrons in the nucleus, while the mass number is the total number of electrons in an atom.

Correct answer: A

Rationale: The atomic number of an atom represents the number of protons in its nucleus, which defines the element's identity. On the other hand, the mass number corresponds to the total sum of protons and neutrons in the nucleus. Therefore, the key distinction between the atomic number and the mass number lies in the fact that the atomic number specifically counts the protons, whereas the mass number encompasses both protons and neutrons. Choice B is incorrect because the atomic number is not related to the number of electrons but rather to the number of protons. Choice C is incorrect because the atomic number is not the number of neutrons but the number of protons. Choice D is incorrect because the atomic number does not include neutrons; it is solely the number of protons.

2. What is the main function of the epiglottis?

A. To store bile
B. To absorb nutrients
C. To prevent food from entering the trachea
D. To produce digestive enzymes

Correct answer: C

Rationale: The epiglottis is a flap of cartilage located at the base of the tongue that covers the opening of the trachea during swallowing to prevent food and liquids from entering the airway. This action helps direct food and liquids into the esophagus, which leads to the stomach for digestion, while also protecting the respiratory system from potential blockages that could lead to choking or aspiration pneumonia. Options A, B, and D are incorrect as the epiglottis is not involved in storing bile, absorbing nutrients, or producing digestive enzymes. Understanding the role of the epiglottis in the swallowing process is crucial for maintaining proper respiratory and digestive functions.

3. Mrs. Jones's class is conducting an experiment. They will substitute artificial sweetener for sugar in a cookie recipe to determine the effect on the overall color of the baked cookies. Which of the following should be included in the instructions for the experiment?

A. When preparing the batch that includes artificial sweetener, 20% more water should be included.
B. The bake temperature should be decreased from 425°F to 400°F.
C. The batch with artificial sweetener should be baked on a stainless steel sheet.
D. Ingredient proportions, bake time, bake temperature, and cookie sheet material should all be kept the same between the two batches.

Correct answer: D

Rationale: To ensure a valid comparison and isolate the impact of the artificial sweetener, the experiment should maintain consistency in all factors except the sugar substitution. By keeping ingredient proportions, bake time, bake temperature, and cookie sheet material the same, any observed differences in the color of the cookies can be attributed to the artificial sweetener rather than other variables. Choices A, B, and C introduce additional variables that could confound the results. Choice A would alter the consistency of the recipe by adjusting the water content, Choice B would introduce a change in baking temperature which could affect the outcome, and Choice C suggests a change in the type of baking sheet used, potentially impacting the baking process and results. Therefore, maintaining consistency in all other factors except for the sugar substitution is crucial for a reliable experiment.

4. Balance the chemical equation: C4H10 + O2 → CO2 + H2O. What is the coefficient for oxygen?

A. 5
B. 6
C. 7
D. 8

Correct answer: B

Rationale: To balance the chemical equation, we need to ensure that the number of each type of atom is the same on both sides of the equation. In this case, there are 10 oxygen atoms on the right side (5 in CO2 and 5 in H2O). To balance this, we need to add a coefficient of 6 in front of O2 on the left side, resulting in 6 O2 molecules. This change will give us a total of 12 oxygen atoms on both sides, making the equation balanced. Choice A (5) is incorrect because it does not account for all the oxygen atoms present in the products. Choices C (7) and D (8) are incorrect as they would result in an imbalance in the number of oxygen atoms on both sides of the equation.

5. Which type of joint connects the bones of the skull?

A. Synovial
B. Fibrous
C. Cartilaginous
D. Ball-and-socket

Correct answer: B

Rationale: Fibrous joints connect the bones of the skull. These joints are immovable or provide very limited movement, providing stability and protection to the brain. Synovial joints (Choice A) are found in the limbs and allow for a wide range of movements. Cartilaginous joints (Choice C) are connected by cartilage and allow limited movement. Ball-and-socket joints (Choice D) allow for a wide range of motion, such as the hip and shoulder joints, but they do not connect the bones of the skull.