Kilometers.
miles?
You would use the metric unit "liters" to measure the capacity of a hot water tank.
It would probably be miles.
Metres or kilometres in metric; yards or miles in Imperial
Miles is best.
its liters
Pints
Kilogram
You would typically use the metric unit "kilometers" to measure the distance from home to school.
You don't, miles are not a unit in the metric system. All distances are measured in metres. Prefixes are used for multiples or fractions of a metre. Distances that used to be measured in miles would, today, be measured in kilometres.
1 US gallon = 3.78541178 liters. Only if you mean pure water, then 1000 litres of water weighs 1 metric tonne. 1000 litres of water are 264.172052357 gallons that weigh 1 metric tonne.
The letter "k" is used to denote the metric prefix kilo (1000), which is a metric prefix. you would not measure miles in kilomiles. But if you were to, 50k miles would be 50,000 miles.