Final answer:
The least pertinent question to ask a patient who ingested a substance is about the patient's age and weight, whereas the type, amount, and timing of the ingested substance are more critical for initial assessment. so, option 4 is the correct answer.
Step-by-step explanation:
The least pertinent question to ask a patient who ingested a substance is 4) What is the patient's age and weight? The most critical pieces of information are about the substance itself, the amount ingested, and the timing of the ingestion. These details are vital for assessing the severity of the situation and the potential for poisoning or toxicity. While knowing a patient's age and weight can be useful for dosing antidotes or treatments, it is not as directly related to the initial assessment of the potential damage from the ingestion.
In the scenario of accidental ingestion of radioactive material, for instance, knowing what specific radioactive substance was ingested, how much was ingested, and how recently the ingestion occurred, are all essential for determining the immediate health risks and the necessary medical interventions.