Solve this crossword by using the clues that follow.
1. Energy in the form of sunlight is absorbed by the green plants in this process.
4. The reddish-brown substance formed over iron in the presence of oxygen and moisture.
5. This change is permanent and irreversible.
6. The process in which a solid directly changes into gaseous state.
1. It is the change that takes place in case of swinging pendulum of a clock.
2. Occurrence of this is a non-periodic change as well as a natural change.
3. It is a physical change