Nursing Elites

1. What is the difference between a pure substance and a mixture?

• A. Pure substances have a fixed composition, mixtures don't.
• B. Mixtures have a fixed composition, pure substances don't.
• C. Pure substances can be in any state, mixtures are not always solids.
• D. Pure substances are always elements, mixtures are always compounds.

Correct answer: A

Rationale: Pure substances have a definite and constant composition, meaning they are made up of only one type of atom or molecule with fixed proportions. This composition does not vary. On the other hand, mixtures are composed of two or more substances physically combined. The components of a mixture can be present in varying proportions, leading to a variable composition. Choice A is correct as it accurately distinguishes between pure substances and mixtures based on the fixed composition of pure substances and the variable composition of mixtures. Choice B is incorrect because mixtures, not pure substances, have variable compositions. Choice C is incorrect as both pure substances and mixtures can exist in different states. Choice D is incorrect because pure substances can be compounds as well, not exclusively elements, and mixtures can contain elements and compounds.

2. In the K-capture process, a type of electron capture, from which electron shell does the electron get captured?

• A. The outermost s-orbital
• B. An inner p-orbital
• C. An inner d-orbital
• D. Any available electron shell

Correct answer: B

Rationale: The K-capture process involves the capture of an electron from the innermost electron shell, known as the K-shell. The K-shell comprises s and p orbitals. During the K-capture process, an electron is specifically captured from an inner p-orbital within the K-shell. Choices A, C, and D are incorrect because K-capture involves capturing an electron from the innermost shell (K-shell) which consists of s and p orbitals, not the outermost s-orbital, inner d-orbital, or any available electron shell.

3. Which part of the brain controls the coordination of muscle movements?

• A. Cerebrum
• B. Cerebellum
• C. Thalamus
• D. Medulla oblongata

Correct answer: B

Rationale: The cerebellum is the part of the brain responsible for controlling the coordination of muscle movements and helping to maintain balance. It receives information from the sensory systems, the spinal cord, and other parts of the brain to regulate voluntary movements. The cerebrum (choice A) is primarily responsible for higher brain functions such as thinking and decision-making, not muscle coordination. The thalamus (choice C) acts as a relay station for sensory information but is not directly involved in muscle coordination. The medulla oblongata (choice D) is responsible for regulating vital autonomic functions like breathing and heart rate, rather than muscle coordination.

4. What is the primary function of DNA polymerase?

• A. Packaging DNA
• B. Replicating DNA
• C. Transcribing DNA
• D. Translating mRNA

Correct answer: B

Rationale: The correct answer is B: Replicating DNA. DNA polymerase is an enzyme responsible for synthesizing new DNA strands during DNA replication. It adds nucleotides to the growing DNA strand based on the template provided by the existing DNA strand. This process ensures that genetic information is accurately copied and passed on to daughter cells during cell division. Option A, Packaging DNA, refers to the coiling and organization of DNA into chromatin, a process involving histones and other proteins. Option C, Transcribing DNA, involves the synthesis of RNA from a DNA template, a process carried out by RNA polymerase. Option D, Translating mRNA, refers to the process of protein synthesis where the information encoded in mRNA is used to assemble amino acids into a polypeptide chain.

5. What is the term for the number of moles of solute per liter of solution?

• A. Molarity
• B. Molality
• C. Normality
• D. Concentration

Correct answer: A

Rationale: Molarity is the correct term for the number of moles of solute per liter of solution. It is expressed as moles of solute divided by liters of solution. Molality (B) is similar but is moles of solute per kilogram of solvent. Normality (C) is the number of equivalents of solute per liter of solution, and Concentration (D) is a general term for the amount of solute present in a given quantity of solution. Therefore, the correct answer is A, molarity, as it specifically refers to moles of solute per liter of solution.

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