Correct Answer: D

Rationale: Understanding atomic structure is essential for various technological advancements. Designing new materials with tailored properties necessitates knowledge of atomic structure to effectively manipulate their characteristics. Developing advanced electronics and nanotechnology involves working at the atomic level to create smaller, faster, and more efficient devices. Improving nuclear energy production and safety also heavily depends on understanding atomic structure to enhance reactor design and safety measures. Therefore, all the options provided (A, B, and C) are potential applications of understanding atomic structure in modern technology.

Correct Answer: B

Rationale: - In the reaction, potassium ions (K+) and chloride ions (Cl-) are present on both sides of the equation. They are not involved in the formation of the products and remain unchanged. - Lead ions (Pb2+) and nitrate ions (NO3-) are involved in the formation of the products potassium nitrate (KNO3) and lead(II) chloride (PbCl2). - Therefore, the spectator ions in this reaction are K+ and Cl-.

Correct Answer: A

Rationale: The resulting intensity of the combined wave is determined by the individual intensities of the waves. When two coherent light waves interfere, the amplitudes of the waves add up, and the resulting intensity is proportional to the square of the sum of the individual amplitudes. Therefore, the individual intensities of the waves play a crucial role in determining the resulting intensity of the combined wave. Choices B, C, and D are incorrect. The wavelength of the waves and the distance between the waves do affect interference patterns but not the resulting intensity. The color of the waves is determined by the wavelength and does not directly determine the resulting intensity of the combined wave.

Correct Answer: C

Rationale: Activation energy is the energy required to break a chemical bond and initiate a chemical reaction. It is the minimum amount of energy needed to start a chemical reaction by breaking bonds in the reactant molecules. Kinetic energy (option A) is the energy of motion and is not directly related to breaking chemical bonds. Potential energy (option B) is stored energy that can be converted into other forms of energy but is not specifically about breaking chemical bonds. Bond energy (option D) refers to the energy required to break a particular chemical bond in a molecule and is not the general term for the energy needed to break any chemical bond. Activation energy is crucial in determining the rate of a chemical reaction as it affects the probability of reactant molecules colliding with sufficient energy to surpass the energy barrier and form products.

Correct Answer: B

Rationale: Immunosuppressive drugs work by suppressing the immune system's activity, which can increase the risk of infections as the body's ability to fight off pathogens is compromised. While allergies can be a side effect of some medications, the primary concern with immunosuppressive drugs is the increased susceptibility to infections. Therefore, the correct answer is B, increased susceptibility to infections. Choice A, 'Increased risk of developing allergies,' is incorrect as the primary risk associated with immunosuppressive drugs is not related to allergies. Choice C, 'Both A and B,' is incorrect as the main concern is the increased susceptibility to infections rather than developing allergies. Choice D, 'Neither A nor B,' is incorrect as there is a known risk of increased susceptibility to infections when using immunosuppressive drugs.