Question

which statement best describes the difference between a substance at 50°c and at 20°c?
a the average electrical energy of the particles is higher at 50°c.
b the density of the substance is higher at 50°c.
c the average kinetic energy of the particles is higher at 50°c.
d the mass of the substance is greater at 50°c.

Explanation:

To determine the correct statement, we analyze each option:

• Option A: Electrical energy of particles isn't related to temperature changes in a substance (temperature relates to kinetic energy, not electrical energy). Eliminate A.
• Option B: Density of a substance (for most substances, except water in a specific range) generally decreases with increasing temperature as volume expands. So density at 50°C would be lower, not higher. Eliminate B.
• Option C: Average kinetic energy of particles is directly proportional to temperature (from kinetic theory of matter). Higher temperature (50°C vs 20°C) means higher average kinetic energy. This is correct.
• Option D: Mass of a substance is conserved (law of conservation of mass) and doesn't change with temperature. Eliminate D.

Answer:

C. The average kinetic energy of the particles is higher at 50°C.