Given that `,`
`A(s) rarr A(l)DeltaH=x`
`A(l) rarr A(g), DeltaH=y`
The heat of sublimation of `A` will be `:`

Options

A. x - y
B. x + y
C. x or y
D. `-x + y`

Answer

To find the heat of sublimation of substance A, we need to analyze the given reactions and their associated enthalpy changes.

1. **Identify the reactions**:
- The first reaction is the transformation of solid A to liquid A:
\[ A(s) \rightarrow A(l) \quad \Delta H = x \]
- The second reaction is the transformation of liquid A to gas A:
\[ A(l) \rightarrow A(g) \quad \Delta H = y \]

2. **Understand the sublimation process**:
- The sublimation process involves the direct conversion of solid A to gas A:
\[ A(s) \rightarrow A(g) \]
- This process can be viewed as two steps:
1. The solid A first converts to liquid A (with enthalpy change \(x\)).
2. Then, the liquid A converts to gas A (with enthalpy change \(y\)).

3. **Calculate the total heat of sublimation**:
- To find the total heat of sublimation, we need to sum the enthalpy changes of the two steps:
\[ \Delta H_{\text{sublimation}} = \Delta H_{\text{solid to liquid}} + \Delta H_{\text{liquid to gas}} = x + y \]

4. **Conclusion**:
- Therefore, the heat of sublimation of A is:
\[ \Delta H_{\text{sublimation}} = x + y \]

### Final Answer:
The heat of sublimation of A will be \(x + y\).

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