Test: Thermal Equilibrium - EmSAT Achieve MCQ

• From the definition of thermal equilibrium, a system is in thermal equilibrium with its environment if the temperatures of the system and environment are equal.

Calculation:

• The middle wall is weakly conducting. Thus after a long time, the temperature of both parts will equalize.
• The final position of the separating wall is at a distance x from the left end. So it is at a distance of 30 - x from the right end Putting the combined gas equation of one side of the separating wall,

⇒ 30 - x = 2x 
⇒ 3x = 30 
⇒ x = 10 cm
The separator will be at a distance of 10 cm from left end.

• Calcium oxide
  • It is commonly known as quicklime or burnt lime and it is a widely used chemical compound.
  • It is a white, caustic, alkaline, crystalline solid at room temperature.
  • Calcium oxide, commonly known as lime, is a chemical compound with the formula CaO.
  • Calcium oxide, also known as quicklime. It is believed that quicklime is one of the oldest chemicals known to the human race. It can also be referred to as burnt lime or lime.
  • Calcium oxide can be produced by the thermal decomposition of materials like limestone or seashells that contain calcium carbonate (CaCO₃ ; mineral calcite) in a lime kiln. Hence, Option 1 is correct.
  • The process that is used to prepare burnt lime is known as calcination.
  • It is a process that starts with thermally decomposing the reactants at high temperatures but ensuring that the temperature is kept well below the melting point.

• X and Y are in thermal equilibrium. So, they both have the same temperature.
• Given that Y has the same temperature as Z. So Y and Z are in thermal equilibrium.
• Therefore, X, Y, and Z are in thermal equilibrium with each other.
• So, if X is placed in thermal contact with Z, there will be no net transfer of energy.

• Thermal equilibrium exists when two bodies are or have attained the same temperature.
• Hence, two bodies in contact are said to be in thermal equilibrium when no heat flow occurs between the two bodies.

• From above it is clear that if neither heat nor matter flows between the system and the surroundings, then the process is adiabatic. Therefore option 3 is correct.

• If two different metal wires are joined to form a closed circuit and two junctions are kept at different temperatures, a small emf is set up in the circuit in a definite direction. This effect is called a thermoelectric effect or Seebeck effect.
  • The emf developed in the circuit is called thermal emf or Seeback emf and the current called thermoelectric current. Therefore option 1 is correct.

• Heat transfer occurs from higher temperature to lower temperature until both temperatures become the same.
• When the temperature of two objects is the same, they are said to be in thermal equilibrium.
• So the correct answer is option 3 i.e. ​When two objects in contact with each other are at the same temperature.

Any process in which the system returns to its initial state is known as a cyclic process. The change in internal energy after a complete cycle is zero because the system returns to its initial state.

Ƞ=1-T₂/T₁ = 1-(273+127)/(273+227)=1-400/500=1/5
W=ȠQ₁=1/5×10⁴=2000J.