Final answer:
To administer 7.5 mg of diazepam, the nurse should administer 1.5 mL of diazepam injection.
Step-by-step explanation:
To calculate the mL of diazepam to administer, use the formula C1V1 = C2V2, where C1 is the concentration of the diazepam injection, V1 is the volume to be administered, C2 is the desired concentration, and V2 is the desired volume. In this case, the nurse needs to administer 7.5 mg of diazepam, which is equivalent to 1.5 times the concentration of the injection (7.5 mg / 5 mg/mL = 1.5 mL). Therefore, the nurse should administer 1.5 mL (rounded to the nearest tenth) of diazepam.