Correct Answer: B

Rationale: The corrected answer is B: 'Vulva: external structures of the female genitalia.' The vulva includes external structures such as the labia, clitoris, and vaginal opening. These structures play roles in sexual arousal and protection of the internal genital organs. Choices A, C, and D are incorrect because they are internal reproductive organs. The ovaries produce eggs, the uterus houses the developing fetus, and the vagina serves as the birth canal. Hence, they are not components of the female external genitalia.

Correct Answer: C

Rationale: The correct answer is C: Amino Acids. Amino acids, the building blocks of proteins, contain both an amine group and a carboxyl group. The carboxyl group (-COOH) is crucial for the structure and function of proteins as it participates in peptide bond formation. Carbohydrates and DNA do not typically contain carboxyl groups as a functional group. Glycolipids consist of a carbohydrate chain linked to a lipid, but they do not inherently contain a carboxyl group.

Correct Answer: B

Rationale: Silicon has an atomic number of 14, indicating it has 14 protons. The atomic mass of 28.1 AMU accounts for both protons and neutrons in the nucleus. By subtracting the atomic number from the atomic mass, we can estimate the number of neutrons in the atom. Thus, 28.1 - 14 = 14 neutrons. Choice A is incorrect as it represents the total atomic mass, not the number of neutrons. Choice C is incorrect; it is the atomic number (protons) rather than the number of neutrons. Choice D is incorrect as it is a value that does not reflect the number of neutrons in the silicon atom.

Correct Answer: C

Rationale: To balance the combustion equation CxHy + O2 → xCO2 + y/2 H2O, we need to balance the carbon and hydrogen atoms. The balanced equation for the given combustion is: 2C H4 + 9O2 → 2CO2 + 4H2O. This means that the correct coefficients are 2:9:10:4, which corresponds to choice C. Choice A (1:5:5:2) does not balance the equation correctly, choice B (4:10:20:8) has excessive oxygen and does not balance the equation, and choice D (2:5:10:4) does not provide the correct ratio of oxygen to balance the equation.

Correct Answer: D

Rationale: Ionic bonds typically form between a metal, which donates electrons from its s orbital, and a nonmetal, which accepts electrons into its p orbital. This transfer of electrons leads to the formation of an ionic bond. Choice A is incorrect as elements in the same period may vary significantly in their properties. Choice B is incorrect because ionic bonds are usually formed between a metal and a nonmetal, not two nonmetals. Choice C is incorrect because transition metals generally form complex ions through the sharing of electrons, not typical ionic bonds.