Question

At room temperature and pressure, kinetic energy of the particles are minimum in case of:

• A. iron
• B. water
• C. kerosene
• D. methane

Answer 1

Answer:

A. iron

Kinetic Energy and States of Matter

Understanding Kinetic Energy

• Kinetic energy is the energy an object possesses due to its motion. For particles (atoms or molecules), it relates to their movement.
• At a given temperature, the average kinetic energy of particles is the same for all substances. However, the state of matter (solid, liquid, gas) significantly impacts how this kinetic energy is manifested.

States of Matter and Particle Movement

• Solids: Particles are tightly packed in a fixed arrangement. They vibrate about their fixed positions but have minimal translational (moving from one place to another) or rotational movement. Their kinetic energy is primarily vibrational.
• Liquids: Particles are less ordered and can move past each other. They have both vibrational and some translational/rotational movement.
• Gases: Particles are far apart and move randomly and rapidly. They possess high vibrational, rotational, and translational kinetic energy.

Iron vs. Other Substances at Room Temperature and Pressure

• The question implies a comparison of kinetic energy manifestation across different states of matter.
• At room temperature and pressure, iron is a solid. Its particles are held in a fixed lattice structure and primarily exhibit vibrational motion.
• Substances that are liquids or gases at room temperature and pressure (e.g., water, oxygen) have particles with more freedom to move, hence exhibiting higher translational and rotational kinetic energy in addition to vibrational energy.
• Therefore, the kinetic energy of the particles is minimum in terms of freedom of movement and translational motion in solids like iron compared to liquids and gases.