The examples of chemical weathering from your list are:
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Oxidation of certain metals in rocks - This is a chemical reaction where oxygen reacts with minerals in the rock, altering their structure and composition.
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Acid rain breaking down compounds in rock statues - Acid rain contains weak acids that can react chemically with minerals in the rock, leading to breakdown and weathering.
The other examples listed involve physical weathering or biological activity, not chemical weathering:
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An increase in temperature in the daytime causing a rock to crack - This is an example of physical weathering due to thermal expansion and contraction.
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Rock breaking apart during a rock slide - This is a form of physical weathering, as it involves the physical movement and breaking apart of rocks.
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An insect digging a hole in a rock for its home - This is a biological activity that can contribute to physical weathering, but it is not a chemical process.
In summary, the first two examples are chemical weathering.