Which of the following statements is/are true?

Options

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

Explanation

To determine which of the statements is true, we will analyze each statement one by one.

### Step 1: Analyze Statement A
**Statement A:** "Celsius is the Celsius unit of temperature."
- This statement is true. The Celsius scale is indeed a unit of temperature measurement. It is commonly used in everyday life and scientific contexts.

### Step 2: Analyze Statement B
**Statement B:** "30 degrees Celsius is equal to 303 Kelvin."
- To convert Celsius to Kelvin, we use the formula:
\[ K = °C + 273 \]
So, for 30 degrees Celsius:
\[ K = 30 + 273 = 303 \text{ Kelvin} \]
- This statement is also true.

### Step 3: Analyze Statement C
**Statement C:** "Heat energy flows from one body to another body. The change in temperature of the bodies need not be equal."
- This statement is true. When heat is transferred from a hotter body to a cooler body, the temperatures of the two bodies will change, but the amount of temperature change does not have to be the same. For example, a small hot object can transfer heat to a large cold object, resulting in a small temperature change for the hot object and a larger temperature change for the cold object.

### Step 4: Analyze Statement D
**Statement D:** "All of the above."
- Since we have determined that Statements A, B, and C are all true, this statement must also be true.

### Conclusion
All the statements A, B, C, and D are true.

### Final Answer
**All of the above statements are true.**

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