Final answer:
The amount of local anesthetic in the dental cartridge of 4% concentration is 72 mg.
Step-by-step explanation:
The concentration of the local anesthetic in the dental cartridge is 4%. This means that for every 100 mL of the solution, there is 4 mL of the anesthetic. Since the cartridge has a volume of 1.8 mL, the amount of anesthetic can be calculated by multiplying the volume of the cartridge by the concentration of the anesthetic:
Amount of anesthetic = Volume of cartridge × Concentration
Amount of anesthetic = 1.8 mL × 4% = 0.072 mL = 72 mg (since 1 mL of water has a mass of 1 g)
Therefore, the amount of local anesthetic in the dental cartridge of 4% concentration is 72 mg (option d).