Across
- 2. constitutes up to 21% of the earth
- 5. gas constitutes up to 90% of Venus and mars
- 7. also found in urea and alkaloids
- 8. outermost layer of the earth
Down
- 1. one of the expensive metal
- 3. constitutes up to 78% of the earth
- 4. helps in preventing soil erosion
- 5. hardest metal in the world
- 6. core innermost layer of the earth