The question asks to identify which of the given materials is an insulator of heat. An insulator is a material that does not allow heat to pass through it easily. Conductors, on the other hand, allow heat to pass through them readily. We need to evaluate each option based on its thermal conductivity.
D) Wood — Wood is an organic material with a fibrous and porous structure. It does not have free electrons, which are responsible for efficient heat transfer in metals. Its cellular structure and trapped air pockets make it a poor conductor of heat, thus classifying it as a good insulator.
The latent heat of vaporization is defined as
The heat required to cool 1 gram of a substance by 1 degree Celsius
The heat required to condense 1 gram of a gas
The heat required to melt 1 gram of a solid at its melting point
The heat required to vaporize 1 gram of a liquid at its boiling point
The question asks for the definition of the latent heat of vaporization. This is a fundamental concept in thermodynamics, specifically related to phase transitions. Latent heat refers to the heat absorbed or released during a phase change (like melting, freezing, vaporization, condensation) without a change in temperature.
Correct Option: D) The heat required to vaporize 1 gram of a liquid at its boiling point
The question asks to identify the phase change that bypasses the liquid state. We need to recall the definitions of common phase transitions and determine which one involves a direct conversion between solid and gas.
Correct Option: C) Sublimation — Sublimation is the direct conversion of a substance from the solid state to the gaseous state without first becoming a liquid. A common example is dry ice (solid carbon dioxide) which sublimes at room temperature and atmospheric pressure.
This question tests fundamental knowledge of the effect of temperature on the physical properties of substances, specifically their volume. We need to recall the concept of thermal expansion.
Correct Option: A) Expand. As temperature increases, the kinetic energy of particles increases, causing them to vibrate more and move further apart, leading to an increase in the substance's volume.
The question asks for the specific term used to describe the temperature at which a liquid transforms into a solid. This is a fundamental concept in physics and chemistry related to states of matter.
Correct Option: C) Freezing point
The question asks about the mode of heat transfer that occurs through direct contact between molecules. We need to identify the correct term among the given options that describes this specific mechanism of heat transfer.
B) Conduction is the transfer of heat through direct contact between molecules or atoms. When particles with higher kinetic energy collide with adjacent particles with lower kinetic energy, they transfer energy, leading to heat propagation.