Correct Answer: A

Rationale:
To gauge a patient's magnesium status, the nurse should check deep tendon reflexes. If the reflex is absent, this may indicate high serum magnesium.

Correct Answer: B

Rationale: Osmosis is the movement of fluid from a region of low solute concentration to a region of high solute concentration across a semipermeable membrane. The number of dissolved particles contained in a unit of fluid determines the osmolality of a solution, which influences the movement of fluid between the fluid compartments. Giving a patient who has a low blood pressure a hypertonic solution will increase the number of dissolved particles in the blood, creating pressure for fluids in the tissues to shift into the capillaries and increase the blood volume. Option A is incorrect; hydrostatic pressure refers to changes in water or volume related to water pressure. Option C is incorrect; diffusion is the movement of solutes from an area of greater concentration to lesser concentration. The solutes in an intact vascular system are unable to move, so diffusion should not normally take place. Option D is incorrect; active transport is the movement of molecules against the concentration gradient and requires ATP as an energy source. This process typically takes place at the cellular level and is not involved in vascular volume changes.

Correct Answer: B

Rationale: Infants are particularly vulnerable to dehydration due to diarrhea, as they have a higher fluid turnover and less reserve.

Correct Answer: B

Rationale: The most common cause of acute respiratory alkalosis is hyperventilation. Extreme anxiety can lead to hyperventilation.

Correct Answer: A

Rationale: A pH of less than 7.40, a PaCO2 greater than 40, and an HCO3 of 24 are normal; therefore, it is a respiratory acidosis. Compensation by the kidneys has not begun, which indicates this was probably an acute event.