which of the following describes how atomic radius varies across the periodic table

ATI TEAS 7

TEAS 7 Science Practice Test

1. Which of the following describes how atomic radius varies across the periodic table?

A. Atomic radius increases from top to bottom and left to right on the periodic table.
B. Atomic radius increases from top to bottom and right to left on the periodic table.
C. Atomic radius increases from top to bottom and toward the halogens on the periodic table.
D. Atomic radius increases from top to bottom and toward the noble gases on the periodic table.

Correct answer: A

Rationale: Atomic radius tends to increase from top to bottom and left to right on the periodic table. This is because as you move down a group (top to bottom), new energy levels are added, increasing the distance of the outer electrons from the nucleus and thus increasing the size of the atom. On the other hand, as you move from left to right across a period, the number of protons and electrons increases, leading to a stronger nuclear charge that attracts the electrons closer to the nucleus, resulting in smaller atomic radii. Choice B is incorrect as atomic radius does not increase from right to left. Choices C and D are incorrect as they incorrectly associate the trend with specific groups of elements (halogens and noble gases) rather than the general trend observed on the periodic table.

2. Which of the following hormones regulates calcium levels in the blood?

A. Insulin
B. Parathyroid hormone
C. Thyroid hormone
D. Glucagon

Correct answer: B

Rationale: The correct answer is B, Parathyroid hormone. Parathyroid hormone plays a crucial role in regulating calcium levels in the blood by increasing calcium levels when they are too low. This hormone acts on the bones, kidneys, and intestines to ensure proper calcium balance in the body. Insulin (choice A) is involved in glucose metabolism, not calcium regulation. Thyroid hormone (choice C) primarily regulates metabolism, and while it indirectly influences calcium levels, it is not the primary regulator. Glucagon (choice D) is involved in increasing blood glucose levels, not calcium regulation.

3. What is the net ionic equation for the reaction: 2HCl(aq) + Ba(OH)2(aq) → 2H2O(l) + BaCl2(aq)?

A. 2H+(aq) + 2OH-(aq) → 2H2O(l)
B. 2HCl(aq) + Ba(OH)2(aq) → BaCl2(aq) + 2H2O(l)
C. 2H+(aq) + Ba2+(aq) → Ba2+(aq) + 2H+(aq)
D. Ba(OH)2(aq) + HCl(aq) → BaCl2(aq) + 2H2O(l)

Correct answer: A

Rationale: In the given reaction, the complete ionic equation is: 2H+(aq) + 2Cl-(aq) + Ba2+(aq) + 2OH-(aq) → 2H2O(l) + Ba2+(aq) + 2Cl-(aq). Spectator ions (Ba2+ and Cl-) do not participate in the net ionic equation, which simplifies to: 2H+(aq) + 2OH-(aq) → 2H2O(l). This equation represents the significant species involved in the reaction, showcasing the formation of water from the combination of hydrogen ions and hydroxide ions, resulting in the production of water molecules.

4. The critical angle is defined as the minimum angle of incidence in a denser medium for which light undergoes:

A. Total internal reflection
B. Continued refraction
C. Specular reflection
D. Increased dispersion

Correct answer: A

Rationale: The critical angle is the minimum angle of incidence in a denser medium at which light undergoes total internal reflection instead of refraction. This phenomenon occurs when light travels from a denser medium to a less dense medium, and the angle of incidence is greater than the critical angle. Total internal reflection is a crucial concept in optics and is utilized in various applications such as fiber optics and prisms. Choice B, 'Continued refraction,' is incorrect as the critical angle specifically marks the point at which total internal reflection occurs, not continued refraction. Choice C, 'Specular reflection,' does not accurately describe the phenomenon associated with the critical angle. Choice D, 'Increased dispersion,' is unrelated to the concept of the critical angle and does not describe the behavior of light at this specific point.

5. Which of the following is NOT a function of the endocrine system?

A. Regulating growth and development
B. Maintaining blood sugar levels
C. Controlling mood and emotions
D. Facilitating digestion through muscle contractions

Correct answer: D

Rationale: The endocrine system is responsible for producing hormones that regulate various bodily functions such as growth, metabolism, mood, and more. Facilitating digestion through muscle contractions is primarily the role of the muscular and nervous systems, not the endocrine system. Therefore, option D is the correct answer as it does not align with the functions typically attributed to the endocrine system. Choices A, B, and C are functions that are indeed associated with the endocrine system, making them incorrect answers in the context of this question.