One word answer is given for the following definitions, Mark the one which is incorrect.

Options

A. The process in which temperature remains constant : Isobaric
B. The process in which volume remains constant : Isochoric
C. The relation between `DeltaH and DeltaH` when all the reactants and products are solid : `DeltaH=DeltaU`
D. The relation between `DeltaG, DeltaH and DeltaS:`
`DeltaG=DeltaH-TDeltaS`

Answer

To solve the question, we need to analyze the definitions provided and identify which one is incorrect based on the provided options.

### Step-by-Step Solution:

1. **Understanding the Definitions**:
- The question asks us to identify the incorrect one-word answer that corresponds to specific thermodynamic definitions.

2. **Analyzing Each Option**:
- **Option 1**: "The process in which temperature remains constant is isobaric."
- This statement is incorrect. The correct term for a process where temperature remains constant is **isothermal**. An isobaric process is one where pressure remains constant.

- **Option 2**: "The process in which volume remains constant is isochoric."
- This statement is correct. An isochoric process is defined as one where the volume remains constant.

- **Option 3**: "The relation between ΔH and ΔU when all reactants and products are solid."
- This statement is also correct. When all reactants and products are solids, the change in enthalpy (ΔH) is equal to the change in internal energy (ΔU) because ΔNG (change in the number of moles of gas) is zero.

- **Option 4**: "The relation between ΔG, ΔH, and ΔS."
- This statement is correct. The Gibbs free energy equation relates these variables as ΔG = ΔH - TΔS.

3. **Identifying the Incorrect Option**:
- From the analysis, we can see that the first option is incorrect. The correct term for a process where temperature remains constant is **isothermal**, not isobaric.

### Final Answer:
The incorrect one-word answer is **isobaric**.

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