a) Green chernistry has been developed in bio chemistry toxicology, physical chemistry, etc.
b) Coal and petroleum are synthesized using green chemistry.

Explanation

**Step-by-Step Solution:**

1. **Understanding Green Chemistry**: Green chemistry is a field of chemistry that focuses on designing chemical products and processes that reduce or eliminate the use and generation of hazardous substances. It aims to create safer and more sustainable chemical processes.

2. **Evaluating Statement (a)**: The first statement claims that green chemistry has been developed in biochemistry, toxicology, physical chemistry, etc. This is true. Green chemistry principles are applied across various fields, including biochemistry and toxicology, to create safer chemical processes and products.

3. **Evaluating Statement (b)**: The second statement claims that coal and petroleum are synthesized using green chemistry. This statement is incorrect. While green chemistry aims to create sustainable processes, coal and petroleum are traditional fossil fuels that are not synthesized through green chemistry methods. Instead, green chemistry focuses on developing alternative materials, such as bioplastics and flame-resistant materials, which are more environmentally friendly.

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