Read the passage carefully and answer the following question:
After several years, a rocky mountain develops cracks due to repeated heating during the day and cooling at night. During the rainy season, the broken rock pieces are washed into a nearby river. At home, Meena lights a candle during a power cut. She notices that the wax near the flame melts, while the candle continues to burn and produce light. Her teacher explains that the melting of wax and the burning of wax are two different types of changes taking place at the same time.
1. Which natural process caused the rocks to develop cracks?
2. Which type of change occurs when the wax vapour burns?
3. Which statement best describes weathering?
4. Which agent mentioned in the passage caused erosion?