✅ Correct Answer: mass/charge (m/z)

📌 Detailed Explanation:

In mass spectrometry, ions generated in the ionizing chamber are detected based on their mass-to-charge ratio, commonly represented as m/z.

• Mass (m): The actual mass of the ion.
• Charge (z): The number of charges the ion carries (e.g., +1, +2).
• m/z: The instrument separates and detects ions based on how their mass compares to their charge.

This ratio determines how ions travel through electric or magnetic fields inside the spectrometer. Ions with different m/z values will deflect differently and reach the detector at different points.

❌ Why the Other Options Are Incorrect:

• A. Mass: Mass alone does not determine the ion’s path unless charge is also considered.
• B. Size: Physical size is not a determining factor in ion trajectory in mass spectrometry.
• D. Structure: Structural information is inferred after analysis but not used directly in sensing particles’ paths.
• E. Charge/Mass: This is the inverse of the correct ratio (mass/charge), which is how instruments are calibrated.

🧾 Summary:

✔️ Mass spectrometers detect ions based on: mass/charge (m/z)

✔️ This allows accurate separation and identification of substances in a sample based on ion trajectories.