A catalyst increases the rate of a reaction by: MCQ with Answer and Explanation

Explanation:
Robert Millikan, along with Harvey Fletcher, performed the famous oil drop experiment in 1909. By observing the motion of tiny charged oil droplets in an electric field, Millikan accurately determined the elementary charge of a single electron to be approximately 1.592 × 10^-19 coulombs (later refined to 1.602 × 10^-19 C).

Explanation:
Copper is below hydrogen in the reactivity series, so it cannot displace hydrogen from dilute acids (non-oxidizing acids like HCl or H₂SO₄). Magnesium, zinc, and iron are above hydrogen and react to produce H₂ gas. However, copper reacts with oxidizing acids like HNO₃ and hot conc. H₂SO₄, but not to produce H₂—they produce NO₂/SO₂.

Explanation:
Distilled water is a pure compound (H₂O) with a fixed composition and distinct properties. Milk is a colloid of fat, protein, etc. Air is a homogeneous mixture of gases. Sea water is a solution of salts. Pure substances are either elements or compounds; mixtures contain two or more substances physically combined. Distillation removes dissolved salts and impurities.