Question

200 g of water is heated from 40°C to 60°C. The change in its internal energy [No expansion is taken place] specific heat of water is 4200 J kg⁻¹ K⁻¹

• A. 16.8 kJ
• B. 10.8 kJ
• C. 8.4 kJ
• D. 14.8 kJ

Hint:

When calculating changes in internal energy, use the formula \( \Delta U = m \cdot c \cdot \Delta T \), where \( c \) is the specific heat capacity, and \( \Delta T \) is the change in temperature.

Answer 1

The Correct Option is A

The change in internal energy is given by:

\[ \Delta U = m \cdot c \cdot \Delta T \] Where:
- \( m = 0.2 \, \text{kg} \) (200 g),
- \( c = 4200 \, \text{J/kg°C} \),
- \( \Delta T = 60^\circ C - 40^\circ C = 20^\circ C \).

Substituting the values:
\[ \Delta U = 0.2 \times 4200 \times 20 \] \[ \Delta U = 16800 \, \text{J} = 16.8 \, \text{kJ} \] Final Answer:
The change in internal energy is:
\[ \boxed{16.8 \, \text{kJ}} \]