Question

which of these sentences have the correct si units? a dime is about 1 g thick. water boils at 100°c. a carton holds 1.89 l of milk. a teaspoon of medicine is about 5 cm. the mass of a paper clip is 5 g/cm³. a football field is about 91 m long.

Explanation:

• For "A dime is about 1 g thick": "g" (gram) is a unit of mass, not length (thickness should use a length unit like mm or cm), so incorrect.
• For "Water boils at 100°C": The SI unit for temperature is Kelvin (K), but °C is a commonly used metric unit for temperature in many contexts, and 100°C is the correct temperature for water boiling at standard pressure. However, strictly SI unit is K, but this is a common acceptable metric unit here.
• For "A carton holds 1.89 L of milk": "L" (liter) is a metric unit for volume (SI unit for volume is cubic meter, but liter is a derived metric unit and widely used for liquid volume), so this is acceptable.
• For "A teaspoon of medicine is about 5 cm": "cm" (centimeter) is a length unit, but a teaspoon of medicine is a volume, so unit is incorrect.
• For "The mass of a paper clip is 5 g/cm³": "g/cm³" is a unit of density, not mass (mass should use g or kg), so incorrect.
• For "A football field is about 91 m long": "m" (meter) is the SI unit for length, and this is correct.

So the sentences with correct (or acceptable) units are "Water boils at 100°C", "A carton holds 1.89 L of milk", and "A football field is about 91 m long".

Answer:

• Water boils at \( 100^\circ\text{C} \)
• A carton holds \( 1.89 \, \text{L} \) of milk
• A football field is about \( 91 \, \text{m} \) long