Cathode rays are made up of electrons. Anode rays are made up of — Atomic Structure Chemistry Question

💡 Solution & Explanation

### Step 1 - Origin of Anode Rays in a Discharge Tube In a gaseous discharge tube, high-speed electrons (cathode rays) collide with neutral gas atoms and ionize them: $$\ce{M(g) + e^- -> M^+(g) + 2e^-}$$ The resulting positively charged species ($\ce{M^+}$) are attracted toward the negative electrode (cathode). When holes are made in the cathode, these positive ions pass through them, forming **anode rays** (or canal rays). --- ### Step 2 - Subatomic Nature of Anode Ray Constituents Since anode rays are formed from ionization of the gas inside the tube, their composition depends on the gas used: * If hydrogen gas is used: anode rays contain protons ($\ce{H^+}$). * If heavier gases (like He, Ne, Ar) are used: anode rays contain positive ions that still contain neutrons, protons, and remaining orbital electrons. Therefore, the particles of anode rays are best described as the **positive residue of atoms** — atoms that have lost one or more electrons and carry a net positive charge. --- ### Step 3 - Detailed Option Analysis * **Option (A) only protons:** Incorrect. Only true if hydrogen gas is used. For all other gases, positive ions contain neutrons and remaining electrons in addition to protons. * **Option (B) only nucleus of atoms:** Incorrect. Under standard discharge conditions, atoms are only partially ionized (losing typically one electron) and retain some orbital electrons. They are not bare nuclei. * **Option (C) positive residue of atoms:** Correct. Positive gaseous ions represent the positively charged remaining part — the positive residue — of the atoms. * **Option (D) only from all the positive particles present in the atoms:** Incorrect. Anode ray ions are structured atomic species that also contain remaining orbital electrons. $$\text{Correct Option: } \boxed{\text{C}}$$