how do isotopes affect the atomic mass of an element

ATI TEAS 7

TEAS 7 science practice

1. How do isotopes affect the atomic mass of an element?

A. Isotopes have no effect on the atomic mass of an element.
B. Isotopes cause the atomic mass of an element to vary slightly.
C. Isotopes cause the atomic mass of an element to be exactly the same for all isotopes of that element.
D. Isotopes cause the atomic mass of an element to vary greatly.

Correct answer: B

Rationale: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Since the atomic mass of an element is the weighted average of the masses of its isotopes, the presence of isotopes causes the atomic mass of an element to vary slightly. This variation occurs because different isotopes have different masses due to their varying numbers of neutrons. The atomic mass is affected by the abundance of each isotope, leading to a slight fluctuation in the overall atomic mass of the element. Choice A is incorrect because isotopes do influence the atomic mass. Choice C is incorrect because isotopes have different masses, affecting the overall atomic mass. Choice D is incorrect as isotopes typically do not cause a significant variation in atomic mass, but rather a slight fluctuation.

2. What is the principle behind the phenomenon of refraction, where waves bend when entering a new medium?

A. Change in wavelength
B. Change in frequency
C. Change in wave speed
D. None of the above

Correct answer: C

Rationale: Refraction occurs due to a change in wave speed when waves enter a new medium. As waves travel from one medium to another, their speed changes, causing them to bend. This change in speed is responsible for the bending of waves during refraction. It is not the change in wavelength or frequency that causes refraction, but rather the change in speed as waves move through different mediums. Therefore, the correct answer is the change in wave speed (Choice C). Choices A and B are incorrect as refraction is not primarily influenced by changes in wavelength or frequency, but by changes in wave speed. Choice D is also incorrect as there is a specific principle, which is the change in wave speed, behind the phenomenon of refraction.

3. Which muscle causes a joint to bend?

A. Cardiac
B. Extension
C. Flexor
D. Smooth

Correct answer: C

Rationale: The correct answer is C: Flexor. A flexor muscle contracts to bend a joint, such as bending the elbow or knee. Flexor muscles are responsible for flexing or bending a joint, while extensor muscles are responsible for extending or straightening a joint. Choice A, Cardiac, is incorrect as cardiac muscle is found in the heart and is responsible for pumping blood. Choice B, Extension, is incorrect as extension refers to the straightening or extending movement of a joint, which is opposite to bending. Choice D, Smooth, is incorrect as smooth muscles are involuntary muscles found in organs like the intestines and blood vessels, not directly responsible for bending joints.

4. Which of the following is the main organ responsible for regulating blood pressure?

A. Heart
B. Kidneys
C. Adrenal glands
D. Pituitary gland

Correct answer: B

Rationale: The kidneys play a crucial role in regulating blood pressure through various mechanisms. One of the key ways the kidneys regulate blood pressure is by controlling the volume of blood in the body. They do this by adjusting the amount of water and sodium excreted in the urine. The renin-angiotensin-aldosterone system, primarily controlled by the kidneys, also plays a significant role in blood pressure regulation. This system helps to maintain blood pressure by regulating blood volume and systemic vascular resistance. While the heart, adrenal glands, and pituitary gland are involved in various aspects of the cardiovascular and endocrine systems, the kidneys are the main organ responsible for regulating blood pressure.

5. Which of the following represents the strongest scientific argument?

A. Scientific Hypothesis
B. Scientific Law
C. Scientific Study Conclusion
D. Scientific Theory

Correct answer: D

Rationale: The correct answer is D, 'Scientific Theory.' A scientific theory is a well-substantiated explanation of an aspect of the natural world. It is based on a large body of evidence and has withstood rigorous testing and scrutiny. Scientific theories are considered the strongest scientific arguments because they have predictive power and are supported by a significant amount of empirical data. Choice A, 'Scientific Hypothesis,' is a proposed explanation for a phenomenon but lacks the extensive evidence and testing that theories undergo. Choice B, 'Scientific Law,' describes a consistent and predictable relationship between variables but does not explain why the relationship exists. Choice C, 'Scientific Study Conclusion,' may be based on a single study and lacks the comprehensive nature and validation that theories possess.