Why do Neon (Ne) and Helium (He) belong to Group 18 (Noble Gases)?

Correct Answer: A

Rationale: Neon (Ne) and Helium (He) belong to Group 18 (Noble Gases) because they have complete and stable outer electron shells. The stability of these outer electron shells is due to the balance of attractive forces between the positively charged protons in the nucleus and the negatively charged electrons in the outer shell. This balance is maintained by the electromagnetic force, which is responsible for holding atoms together and determining their chemical properties. Gravity (Choice B) is a force of attraction between objects with mass and is not responsible for the stability of electron shells. The strong nuclear force (Choice C) and weak nuclear force (Choice D) are forces that act within the nucleus of an atom and are not directly related to the stability of outer electron shells in determining an element's group in the periodic table.

Correct Answer: C

Rationale: The correct answer is the strong nuclear force. It is an incredibly powerful force that overcomes the repulsive electrostatic force between protons, binding them together and stabilizing the nucleus. The strong nuclear force is essential for maintaining the integrity and stability of an atom's nucleus. Electromagnetism (Choice A) is responsible for interactions between charged particles but is not the primary force holding the nucleus together. Gravity (Choice B) is a very weak force at the nuclear level and is not responsible for binding protons and neutrons in the nucleus. The weak nuclear force (Choice D) is involved in certain types of radioactive decay processes, but it is not the force responsible for holding the nucleus together.

Correct Answer: D

Rationale: Carotene is the pigment responsible for the yellow color of bananas. It belongs to a group of plant pigments called carotenoids, which are responsible for giving fruits and vegetables their vibrant colors, including the yellow hue of bananas. Potassium, calcium, and phosphorus are essential minerals found in bananas but are not responsible for their yellow color.

Correct Answer: B

Rationale: Carbon is the correct answer as it is a critical element in DNA and RNA, forming the backbone of these molecules. Its ability to form diverse bonds allows for efficient storage and transmission of genetic information. Oxygen, nitrogen, and hydrogen are also present in DNA and RNA but do not serve as the primary backbone element for these molecules. Oxygen is involved in the structure but not as the backbone element. Nitrogen is present in the bases of nucleotides, and hydrogen bonds help stabilize the structure.

Correct Answer: C

Rationale: The correct answer is C, Cardiac muscle. Cardiac muscle fits the description provided in the question as it exhibits involuntary contractions, striations, and is predominantly located in the heart. Skeletal muscle, while also striated, is voluntary and not involuntary like cardiac muscle. Smooth muscle lacks striations and is typically found in the walls of internal organs. Elastic muscle is not a recognized type of muscle tissue in human anatomy, making it an incorrect choice.