The mass of the school bus is expressed in kilograms, offering a suitable measure for its considerable weight. Ravi's travel distance is in kilometers, providing a practical scale for vehicle distances. For Goran's cream addition, milliliters are apt, avoiding excess in measurement for a small quantity.
(a) The school bus had a mass of about 9000 kilograms. The unit "kilograms" is appropriate for expressing the mass of heavy objects like a school bus.
(b) Last week, Ravi drove about 13 kilometers to visit his uncle. The unit "kilometers" is suitable for measuring the distance traveled by a vehicle, providing a larger scale than meters for such purposes.
(c) Goran added 5 milliliters of cream to his coffee. The unit "milliliters" is used for small quantities of liquids, making it suitable for measuring the amount of cream added to the coffee. Liters would be excessive for such a small quantity.