ATI TEAS 7 Science

Correct Answer: D

Rationale: The correct answer is D, the independent variable. This is the variable that is intentionally changed or manipulated by the researcher in a scientific investigation to observe its effect on the dependent variable. By varying the independent variable, the researcher can determine if changes in this variable cause changes in the dependent variable. The control (B) is used as a baseline for comparison, the hypothesis (C) is a proposed explanation, and the dependent variable (A) is the variable being measured as a result of changes in the independent variable.

Correct Answer: B

Rationale: The correct answer is B: Protons and neutrons only. Electrons are not found in the nucleus, as they orbit around the nucleus in electron shells. Protons and neutrons are the subatomic particles found within the nucleus of an atom. Protons have a positive charge, while neutrons are neutral. The nucleus contains almost all of the atom's mass and is positively charged due to the presence of protons. Choice A is incorrect because electrons are not part of the nucleus. Choice C is incorrect because electrons are not present in the nucleus. Choice D is incorrect as protons and neutrons are indeed constituents of the atomic nucleus.

Correct Answer: A

Rationale: The correct answer is A: Meters per second. The speed of light in a vacuum is a measure of how fast light travels, which is approximately 299,792,458 meters per second. This unit is commonly used in physics to quantify the speed of light. Hertz (B) is a unit of frequency, Candela (C) is a unit of luminous intensity, and Newton (D) is a unit of force, not speed. Therefore, A is the correct unit to measure the speed of light in a vacuum.

Correct Answer: A

Rationale: The correct answer is A: Hydrogen gas and sodium chloride (NaCl). When NaOH reacts with HCl, a neutralization reaction occurs, forming water and a salt. NaOH + HCl -> NaCl + H2O. Sodium chloride and water are the products formed in this reaction. Hydrogen gas is also produced as a byproduct. Choices B, C, and D are incorrect as they do not represent the correct products of the reaction based on the chemical equation.

Correct Answer: B

Rationale: The correct answer is B. A decomposition reaction involves a single compound breaking down into two or more simpler substances. In choice B, CaCO3 decomposes into CaO and CO2. This reaction follows the general form AB → A + B, making it a clear example of a decomposition reaction. Choices A, C, and D involve synthesis or combination reactions, where simpler substances combine to form a more complex compound, making them incorrect for this question.