NLN Updated NEX Exam Questions and Answers by aminah

Water is a polar molecule because it has an unequal distribution of electrical charge, with a slightly negative oxygen atom and slightly positive hydrogen atoms. This polarity causes water molecules to attract one another through hydrogen bonding. Option C demonstrates this property because water molecules stick together (cohesion) and do not mix with nonpolar substances like oil. Oil molecules lack polarity and cannot form hydrogen bonds with water, so the two substances separate into layers. The other options describe physical movement, gravity, or resistance, none of which are direct results of polarity. The NEX Science exam frequently tests molecular properties such as polarity by connecting them to real-world examples like oil and water separation. Recognizing hydrogen bonding and cohesion as outcomes of water’s polarity is essential for answering these questions correctly.

The passage states that lack of sleep weakens immune function and increases susceptibility to illness. This supports the conclusion that adequate sleep supports immune health. Option C accurately reflects this relationship. Options A and D contradict the passage, while option B exaggerates the effect. NEX questions often test the ability to infer logical conclusions without overgeneralizing.

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The passage explains that herd immunity occurs when a large percentage of the population is vaccinated, which helps protect those who cannot receive vaccines. Option B correctly states this benefit. The passage does not suggest that herd immunity eliminates all diseases or replaces hygiene practices. It also does not mention reducing side effects. On the NEX exam, cause-and-effect questions require identifying the specific outcome discussed rather than making broad assumptions. Herd immunity’s protective effect on vulnerable individuals is the key idea.

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“Essential” means absolutely necessary or vital. Option C is the correct synonym. The other options are opposites or unrelated. Essential is a high-frequency NEX word, especially in health and science contexts.