1. The problem is to convert various metric units of length, mass, and volume using the given conversion factors. 2. Important conversion rules: - Length: $10\ \text{mm} = 1\ \text{cm}$, $100\ \text{cm} = 1\ \text{m}$, $1000\ \text{m} = 1\ \text{km}$ - Mass: $1000\ \text{g} = 1\ \text{kg}$, $1000\ \text{kg} = 1\ \text{t}$ - Volume: $1000\ \text{ml} = 1\ \text{l}$, $1000\ \text{l} = 1\ \text{m}^3$, and $1\ \text{ml} = 1\ \text{cm}^3$ 3. Step-by-step conversions: Length: 1. $85\ \text{cm} = \frac{85}{100} = 0.85\ \text{m}$ 2. $2.4\ \text{km} = 2.4 \times 1000 = 2400\ \text{m}$ 3. $0.63\ \text{m} = 0.63 \times 100 = 63\ \text{cm}$ 4. $25\ \text{cm} = \frac{25}{100} = 0.25\ \text{m}$ 5. $7\ \text{mm} = \frac{7}{10} = 0.7\ \text{cm}$ 6. $2\ \text{cm} = 2 \times 10 = 20\ \text{mm}$ 7. $1.2\ \text{km} = 1.2 \times 1000 = 1200\ \text{m}$ 8. $7\ \text{m} = 7 \times 100 = 700\ \text{cm}$ 9. $0.58\ \text{km} = 0.58 \times 1000 = 580\ \text{m}$ 10. $815\ \text{mm} = \frac{815}{1000} = 0.815\ \text{m}$ 11. $650\ \text{m} = \frac{650}{1000} = 0.65\ \text{km}$ 12. $25\ \text{mm} = \frac{25}{10} = 2.5\ \text{cm}$ Mass: 13. $5\ \text{kg} = 5 \times 1000 = 5000\ \text{g}$ 14. $4.2\ \text{kg} = 4.2 \times 1000 = 4200\ \text{g}$ 15. $6.4\ \text{kg} = 6.4 \times 1000 = 6400\ \text{g}$ 16. $3\ \text{kg} = 3 \times 1000 = 3000\ \text{g}$ 17. $0.8\ \text{kg} = 0.8 \times 1000 = 800\ \text{g}$ 18. $400\ \text{g} = \frac{400}{1000} = 0.4\ \text{kg}$ 19. $2\ \text{t} = 2 \times 1000 = 2000\ \text{kg}$ 20. $250\ \text{g} = \frac{250}{1000} = 0.25\ \text{kg}$ 21. $0.5\ \text{t} = 0.5 \times 1000 = 500\ \text{kg}$ 22. $0.62\ \text{t} = 0.62 \times 1000 = 620\ \text{kg}$ 23. $7\ \text{kg} = \frac{7}{1000} = 0.007\ \text{t}$ 24. $1500\ \text{g} = \frac{1500}{1000} = 1.5\ \text{kg}$ Volume: 25. $800\ \text{ml} = \frac{800}{1000} = 0.8\ \text{l}$ 26. $21\ \text{ml} = 0.021\ \text{l}$ 27. $1000\ \text{ml} = 1\ \text{l}$ 28. $4.51\ \text{ml} = 0.00451\ \text{l}$ 29. $6\ \text{l} = 6000\ \text{ml}$ 30. $3\ \text{l} = 3000\ \text{cm}^3$ 31. $2\ \text{m}^3 = 2000\ \text{l}$ 32. $5.5\ \text{m}^3 = 5500\ \text{l}$ 33. $0.91\ \text{cm}^3 = 0.00091\ \text{l}$ 34. $600\ \text{cm}^3 = 0.6\ \text{l}$ 35. $15\ \text{m}^3 = 15000\ \text{l}$ 36. $240\ \text{ml} = 0.24\ \text{l}$ Additional length conversions: 37. $28\ \text{cm} = 0.28\ \text{m}$ 38. $5.5\ \text{m} = 550\ \text{cm}$ 39. $305\ \text{g} = 0.305\ \text{kg}$ 40. $0.046\ \text{km} = 46\ \text{m}$ 41. $16\ \text{ml} = 0.016\ \text{l}$ 42. $208\ \text{mm} = 0.208\ \text{m}$ 43. $28\ \text{mm} = 2.8\ \text{cm}$ 44. $27\ \text{cm} = 0.27\ \text{m}$ 45. $788\ \text{m} = 0.788\ \text{km}$ 46. $14\ \text{t} = 14000\ \text{kg}$ 47. $1.3\ \text{kg} = 1300\ \text{g}$ 48. $901\ \text{m}^3 = 901000\ \text{l}$ 49. $2.9\ \text{t} = 2900\ \text{kg}$ 50. $19\ \text{ml} = 0.019\ \text{l}$ 51. Appropriate metric units: a) Distance between Madrid and Barcelona: $\text{km}$ b) Capacity of a wine bottle: $\text{ml}$ or $\text{l}$ c) Mass of raisins for a cake: $\text{g}$ d) Diameter of a small drill: $\text{mm}$ e) Mass of a car: $\text{kg}$ or $\text{t}$ f) Area of a football pitch: $\text{m}^2$ or $\text{km}^2$ depending on size This completes all conversions and unit identifications.