ATI TEAS 7 Science Practice Test

Correct Answer: A

Rationale: The number of protons in an oxygen atom is a constant. This value is determined by the atomic number of the element and does not change regardless of the isotope of oxygen. The number of protons defines the element and remains consistent under normal conditions. Choices B, C, and D are not constants. The temperature at which iron ore will melt can vary depending on factors like pressure, the human population size is constantly changing, and the time the sun rises each day varies with the seasons and location.

Correct Answer: C

Rationale: A substance is considered acidic if its pH is less than 7. pH values below 7 indicate acidity, while pH values above 7 indicate alkalinity or basicity. Substances with a pH less than 7 are categorized as acidic, not above it. Therefore, a substance is classified as acidic if its pH is less than 7, making choice C the correct answer. Choices A, B, and D are incorrect because a pH of 12, 9, and 4, respectively, are all above 7, and therefore not indicative of acidity.

Correct Answer: B

Rationale: A triple beam balance is used to measure mass, typically in grams. Liters, meters, and gallons are units of volume, length, and capacity, respectively, not typically measured using a triple beam balance. Therefore, the correct answer is grams. Choice A, Liters, is a unit of volume. Choice C, Meters, is a unit of length. Choice D, Gallons, is a unit of capacity. These units are not typically measured using a triple beam balance.

Correct Answer: C

Rationale: The correct answer is C, Active artificial immunity. Vaccination introduces a weakened or inactive form of the pathogen to stimulate the immune system, leading to the development of immunity. Active artificial immunity is the result of deliberate exposure to an antigen, such as through vaccination, to produce an immune response. Passive immunity, like receiving pre-formed antibodies, does not involve the immune system's activation. Natural immunity is typically acquired through exposure to the pathogen itself, not through vaccination.

Correct Answer: D

Rationale: The atomic mass of an atom is the sum of the protons and neutrons in its nucleus. In this case, the atom has 2 protons and 4 neutrons, totaling 6 particles in the nucleus. Therefore, the approximate atomic mass of this atom is 6, making choice C incorrect. The number of electrons does not significantly contribute to the atomic mass, as they are much lighter and located in the electron cloud surrounding the nucleus. Choices A, B, and C are incorrect as they do not reflect the correct calculation of atomic mass based on protons and neutrons only.