Specific Heat

When two substances at different temperatures are mixed (like hot and cold water), the final temperature T of the mixture lies between the temperatures of the two substances. This means the final temperature will be lower than the hotter sample and higher than the colder sample.

The correct option is (C):

Condensation is the process by which a substance changes its phase from a gaseous state to a liquid state. This typically occurs when the vapor is cooled or comes into contact with a cooler surface, losing energy and forming liquid droplets. It is the reverse process of vaporization or boiling, which converts liquid into gas.

The correct option is (D): gas to liquid

Correct answer: nichrome

Explanation:
Nichrome is an alloy of nickel and chromium and is widely used in heating elements like those in electric irons, toasters, and heaters.

Reasons why nichrome is suitable:
- It has high resistivity, which helps it generate heat when current flows through it.
- It has a high melting point, so it can withstand high temperatures.
- It does not oxidize easily even when red hot, ensuring long life and durability.

In contrast:
- Copper and silver are good conductors but have low resistivity, making them unsuitable for heating.
- Germanium is a semiconductor and not suitable for use as a heating element.

Hence, the correct answer is: nichrome.

Correct answer: higher specific heat

The curry inside the samosa remains hot for a longer time because it contains ingredients with a higher specific heat. Substances with higher specific heat require more heat energy to raise their temperature and also retain heat for a longer duration. - The outer crust cools quickly because it has a lower specific heat. - The inner curry stays hot because it stores more thermal energy due to its higher specific heat. Hence, the correct answer is higher specific heat.

Correct answer: the metal piece only

When we touch a metal piece and a wooden piece, the metal feels colder because metals have high thermal conductivity compared to wood. This means the metal quickly transfers heat away from our fingers, creating a sensation of cold. - The metal piece conducts heat away from your fingers efficiently, so it feels colder. - The wooden piece has low thermal conductivity, so it does not transfer heat away from your fingers as quickly, and feels warmer. Hence, the correct answer is the metal piece only.

The device used to measure the specific heat of a substance is called a .
A calorimeter is an instrument used in calorimetry, the science of measuring the heat of chemical reactions or physical changes as well as heat capacity. It helps in determining the specific heat capacity of a substance.

- A is used to measure small distances or thicknesses with high accuracy.
- A is used to measure properties of light over a specific portion of the electromagnetic spectrum.
- A is used to measure atmospheric pressure.

The correct option is (C):

The heat energy required to change a substance from a solid to a liquid at its melting point is called the latent heat of fusion. This is because the temperature of the substance does not change during the melting process, but energy is still required to overcome the forces holding the particles in the solid state. In contrast, the latent heat of vaporization is the heat required to change a substance from liquid to gas, while specific heat is the amount of heat needed to raise the temperature of a substance.

The correct option is (C): latent heat of fusion

The specific heat values for common substances are:

- Water: 4.186 J/g°C

- Ice: 2.05 J/g°C

- Copper: 0.385 J/g°C

- Aluminum: 0.900 J/g°C -

Iron: 0.450 J/g°C

- Zinc: 0.388 J/g°C

- Kerosene oil: 2.01 J/g°C

Comparing the specific heat values, we can see that Ice: 2.05 J/g°C and Kerosene oil: 2.01 J/g°C are the closest.