TEAS 7 practice test science

Correct Answer: C

Rationale: Elements in Group 18 (Noble gases) are generally unreactive because their outermost electron shells are completely filled. This results in high stability and low reactivity since they have achieved a full valence shell configuration, making them less likely to gain, lose, or share electrons with other atoms. The full valence shell configuration leads to a minimal tendency for these elements to form chemical bonds, hence exhibiting low reactivity. Choices A, B, and D are incorrect because high atomic masses, lack of valence electrons, and existing as single atoms do not directly contribute to the unreactivity of noble gases. It is the full valence shell configuration that is the primary reason for their inert nature.

Correct Answer: B

Rationale: When an atom loses an electron, it gains a positive charge and becomes an ion. This occurs because the number of protons in the atom exceeds the number of electrons, leading to a positive charge. Therefore, the atom undergoes a transformation into an ion by losing an electron. Choice A is incorrect because losing an electron does not result in the formation of a molecule, as molecules are made up of bonded atoms. Choice C is incorrect because losing an electron does not change the fundamental identity of the atom; it only changes its charge. Choice D is incorrect because losing an electron causes the atom to become positively charged, altering its neutrality.

Correct Answer: A

Rationale: When hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), it forms sodium chloride (NaCl) and water (H2O) according to the following chemical equation: HCl + NaOH -> NaCl + H2O. Therefore, the correct answer is NaCl + H2O (Choice A). This reaction is a classic acid-base neutralization reaction where the acid (HCl) reacts with the base (NaOH) to form a salt (NaCl) and water (H2O). Choice B (NaOH + HCl) is incorrect because the order of the reactants matters in a chemical reaction, and in this case, HCl is the acid reacting with NaOH. Choices C (Na2Cl + H2O) and D (NaClO3 + H2) are incorrect because they do not represent the products of the reaction between HCl and NaOH as per the balanced chemical equation.

Correct Answer: D

Rationale: Diabetic nephropathy, a complication of diabetes, affects the nephrons. Nephrons are the functional units of the kidneys responsible for filtering blood and producing urine. The high blood sugar levels associated with diabetes can damage the nephrons over time, leading to kidney dysfunction and, ultimately, kidney failure. Choices A, B, and C are incorrect because diabetic nephropathy primarily impacts the nephrons in the kidneys, not the ureters, bladder, or urethra.

Correct Answer: D

Rationale: Elasticity refers to a material's ability to resist deformation and return to its original shape after stress is applied. It is the property that resists a change in shape. Density is the mass per unit volume of a substance. Mass is the amount of matter in an object, while inertia is the tendency of an object to resist changes in its state of motion. Viscosity, not mentioned in the question, is the resistance of a fluid to flow, not shape change.