Gases are bad conductors of electricity. Their conductivity may be increased by — Atomic Structure Chemistry Question

💡 Solution & Explanation

### Step 1 - Why Gases are Bad Conductors at Normal Conditions Gases consist of neutral atoms/molecules. With virtually no free charge carriers, they are excellent insulators. At high pressure: * Molecules are densely packed * **Mean free path** (average distance between collisions) is very small * Any produced ions recombine before reaching the electrodes * Result: no sustained current flow ### Step 2 - Effect of Decreasing Pressure Decreasing pressure: * Reduces gas density → molecules spaced further apart * **Mean free path increases significantly** * Free ions can travel farther without recombining → can reach electrodes * Result: increased conductivity ### Step 3 - Effect of Increasing Potential Difference Increasing potential difference (voltage): * Stronger electric field $E = V/d$ * Accelerates free charges to higher kinetic energy * High-energy ions/electrons collide with neutral molecules → knock out electrons * This **ionization by collision** creates more charge carriers in a cascade * Result: increased conductivity ### Step 4 - Evaluation of Options * **Option (A) Incorrect:** Increasing pressure decreases mean free path → ions recombine more → lower conductivity. * **Option (B) Incorrect:** Decreasing pressure helps (increases mean free path), but decreasing potential difference reduces kinetic energy → insufficient for ionization by collision → less current. * **Option (C) Correct:** Decreasing pressure (↑ mean free path) AND/OR increasing potential difference (↑ kinetic energy → ionization by collision) both increase conductivity. * **Option (D) Incorrect:** Increasing pressure and decreasing potential difference both reduce conductivity. $$\text{Correct Option: } \boxed{\text{C}}$$