Which of the following statements is/are true?

Options

A. Celsius (`""^@C`) is the unit of temperature.
B. `30^@C`=303 K
C. When heat energy flows from one body to another, the change in temperature of the bodies need not be equal.
D. All of the above

Explanation

To determine which statements are true, let's analyze each option step by step.

### Step 1: Analyze Option 1
**Statement:** Celsius is the unit of temperature.

**Explanation:**
- The Celsius scale is indeed a unit of measurement for temperature. It is commonly used in daily life and scientific contexts. The unit is often denoted as °C (degrees Celsius).

**Conclusion:** This statement is **true**.

### Step 2: Analyze Option 2
**Statement:** Celsius is equal to 303 Kelvin.

**Explanation:**
- The relationship between Celsius and Kelvin is given by the formula:
\[ \text{Temperature in Kelvin} = \text{Temperature in Celsius} + 273 \]
- If we rearrange this formula to find the Celsius equivalent of 303 Kelvin:
\[ \text{Temperature in Celsius} = 303 - 273 = 30 \text{°C} \]
- Therefore, the statement that Celsius is equal to 303 Kelvin is true when interpreted correctly.

**Conclusion:** This statement is **true**.

### Step 3: Analyze Option 3
**Statement:** When heat energy flows from one body to another, the change in temperature of bodies need not be equal.

**Explanation:**
- When heat is transferred between two bodies, the amount of heat absorbed or released can vary depending on the specific heat capacities of the materials involved. Therefore, it is possible for the temperature change in one body to be different from that in the other body.
- For example, if one body has a higher specific heat capacity, it may not change temperature as much as a body with a lower specific heat capacity when the same amount of heat is transferred.

**Conclusion:** This statement is **true**.

### Final Conclusion
All three statements are true.

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