**Explanation:**

Kharif crops are the crops that are sown in the rainy season and harvested in the autumn season. They are also known as monsoon crops. These crops require a lot of water and are suitable for regions with high rainfall. Kharif crops are typically sown between June and July and harvested between September and October.

Let's analyze each option to determine which one is not a kharif crop:

a) **Rice:** Rice is a major kharif crop. It requires a lot of water and is cultivated in areas with high rainfall. Therefore, rice is a kharif crop.

b) **Rapeseeds:** Rapeseeds, also known as canola, are not typically considered a kharif crop. They are usually sown in the winter season and harvested in the spring season. Therefore, rapeseeds are not a kharif crop.

c) **Cotton:** Cotton is a kharif crop. It requires a warm and humid climate, making it suitable for cultivation during the monsoon season. Therefore, cotton is a kharif crop.

d) **Maize:** Maize, also known as corn, is a kharif crop. It is sown in the rainy season and requires adequate rainfall for its growth. Therefore, maize is a kharif crop.

From the above analysis, we can conclude that option **b) Rapeseeds** is not a kharif crop. Rapeseeds are typically sown and harvested in different seasons compared to kharif crops.