Which of the following is/are in random motion? i. Pollen grains in water ii. The molecules of hydrogen gas ii. Fine chalk particles floating in air
Answer Details
The correct answer is (i), (ii), and (iii).
All the options given are examples of particles that undergo random motion. In liquids, such as water, particles move around in a random manner known as Brownian motion, caused by collisions with other particles. Pollen grains in water, being solid particles, will exhibit Brownian motion. Similarly, gas molecules such as hydrogen gas are in constant random motion, bouncing off one another in all directions. Lastly, small particles, such as fine chalk particles, suspended in air are also subject to random motion due to collisions with air molecules. Therefore, all the options given represent particles undergoing random motion.