The average speed is 75 Km per hour. Remember the equation for speed is Speed = Distance divided by Time
It is hydrogen bond(as well as fh, and h2o), intermolecular force.
Answer : Unit of any measurement can be defined as a definite magnitude of a given quantity, which is defined and adopted by convention or by law, that is widely used as a standard for measurement of the same kind of quantity. If the unit system was not given to the measurements we would haphazardly complicate the calculations.
Example : If someone wrote 500 in the paper as a answer to a question. But forgot to mention the units of the measurements. It can be misinterpreted by anyone as there are no units written besides the number (unit less). Complications grow. One cannot simply predict is it 500 m? 500 g? 500 mL? 500 km? 500 s? or 500 M? anything can be guessed. To be specific about the answer to any problem we should always use units. Which will help to narrow down the approach of any problem and give a measurable related quantity about the associated problem.
