Question

If $1000\text{cal}$ of heat energy is supplied to water at $30°\text{C}$, then .

• A. water starts to boil.
• B. water completely converts to steam.
• C. it will either remain in a liquid state or convert to steam depending on its mass.
• D. quantity of water in the container will decrease.

Answer 1

The correct option is C

it will either remain in a liquid state or convert to steam depending on its mass.

Step 1: Given Data:

The initial temperature of the water $T_I=30°\text{C}$.

The heat energy supplied to the water is $Q=1000\text{cal}$.

Assume, the specific heat capacity of water is $s=1\text{cal/}\left(\text{g·°C}\right)$

Step 2: Specific Heat Capacity:

1. Specific heat capacity of a substance is defined as the amount of heat energy needed to increase the temperature of the unit mass of the substance by one unit.
2. Water has a specific heat capacity $s=1\text{cal/}\left(\text{g·°C}\right)$. Thus, we need to supply $1\text{cal}$ heat energy to $1\text{g}$ of water to increase its temperature by $1°\text{C}$.

Step 3: Analysis:

1. $1\text{g}$ of water at $100°\text{C}$ converts into steam at $100°\text{C}$ if $540\text{cal}$ heat is supplied to the water.
2. Thus, the supplied heat $Q=1000\text{cal}$ can (i) increase the temperature of the water, (ii) bring the water to the boiling point i.e., to $100°\text{C}$, or (iii) convert the water into steam thus decreasing the quantity of water depending on the mass of the water.
3. Since here the mass is not specified, the final state of the water cannot be said definitely.

Hence, the correct option is C.