Question

Which of the following determines the relative mass of atoms and molecules?

• A. Mass spectrometer
• B. Gas analyzer
• C. Liquid chromatograph
• D. Gas chromatograph

Hint:

Think of a mass spectrometer like a "magnetic curve-ball." A light atom is easily "blown off course" by the magnet, while a heavy molecule "plows straight through." By seeing how much they bend, we know their mass.

Answer 1

The Correct Option is A

To determine the precise mass of microscopic particles like atoms and molecules, scientists use an analytical technique that relies on the movement of charged particles in electric and magnetic fields. 1. Working Principle of a Mass Spectrometer: A mass spectrometer works by:

• Ionization: Converting the sample into charged particles (ions).

• Acceleration: Using an electric field to speed up the ions.

• Deflection: Using a magnetic field to bend the path of the ions. The amount of deflection depends on the particle's

mass-to-charge ratio ($m/z$).

• Detection: Measuring where the ions land.

2. Why it is the Correct Choice: By measuring the specific deflection path, the instrument can calculate the relative mass of the atom or molecule with incredible precision. This allows for the identification of isotopes and the determination of molecular structures.

3. Distinguishing from Chromatography: Chromatography (Gas or Liquid) is a

separation technique used to split a complex mixture into its individual parts based on their speed through a medium. While a chromatograph can tell you how much of a substance is there, it doesn't measure atomic mass directly—it often has to be paired with a mass spectrometer (GC-MS) to do that.