Correct Answer: B

Rationale: In a covalent bond, the shared electrons spend more time closer to the more electronegative atom. Electronegativity is the ability of an atom to attract electrons in a chemical bond. The more electronegative atom exerts a stronger pull on the shared electrons, causing them to be closer to that atom. Choice A is incorrect because in a covalent bond, electrons are shared, not completely transferred. Choice C is incorrect as the shared electrons are not equidistant but are closer to one atom due to electronegativity differences. Choice D is incorrect because shared electrons play a significant role in determining the bond strength by the strength of the bond formed through electron sharing.

Correct Answer: C

Rationale: The correct answer is an Electroencephalogram (EEG). An EEG is specifically designed to record the measurable electrical activity of the brain. It does so by using small, flat metal discs (electrodes) attached to the scalp to detect brain activity. This test is crucial in diagnosing various conditions like seizures, epilepsy, head injuries, dizziness, headaches, and brain tumors. The other options, CAT scan, MRI scan, and X-ray, are imaging techniques that do not directly measure the brain's electrical activity. CAT scan and MRI scan provide detailed images of the brain's structure, while X-ray is more suited for visualizing bone structures or dense tissues.

Correct Answer: B

Rationale: The correct answer is B: Alveoli. The alveoli in the lungs are responsible for gas exchange. They have a thin membrane that allows for the exchange of oxygen and carbon dioxide between the air in the lungs and the blood in the capillaries surrounding them. This process is essential for respiration, providing oxygen to the body's tissues and removing carbon dioxide, a waste product of cellular metabolism. Choices A, C, and D are incorrect. The trachea is a passageway that carries air to and from the lungs but is not directly involved in gas exchange. Bronchi are airway passages that further divide into smaller bronchioles leading to the alveoli but do not perform gas exchange themselves. The diaphragm is a muscle involved in the breathing process by aiding in inhalation and exhalation, but it is not the structure responsible for gas exchange in the respiratory system.

Correct Answer: B

Rationale: The correct answer is B: Insulin. Insulin, produced by the pancreas, plays a crucial role in regulating blood sugar levels by facilitating glucose uptake into cells. Thyroxine, adrenaline, and cortisol do not directly regulate blood sugar levels. Thyroxine is produced by the thyroid gland and regulates metabolism. Adrenaline and cortisol are hormones involved in stress responses and do not have a primary function in blood sugar regulation. Understanding the functions of these hormones is crucial in differentiating their roles in the body and identifying the specific hormone responsible for blood sugar regulation.

Correct Answer: C

Rationale: Destructive interference is the term used to describe the phenomenon when two waves meet and their amplitudes are such that they cancel each other out, resulting in a wave with a smaller amplitude or no wave at all. This cancellation effect occurs due to the waves being out of phase. This is in contrast to constructive interference, where two waves combine to produce a wave with a larger amplitude. Refraction is the bending of waves as they pass through different mediums, such as light passing through glass, while diffraction is the bending of waves around obstacles or through openings. In this case, the concept described in the question specifically aligns with destructive interference, making it the correct answer.