Question

question
the kilogram was originally defined to be the mass of one liter of water. after this, the kilogram was redefined based on:
select the correct answer below:
○ a cylinder of platinum - iridium alloy
○ a cylinder of titanium
○ the mass of a kings crown
○ the mass of a gold bar

Explanation:

The kilogram was re - defined based on a cylinder of platinum - iridium alloy known as the International Prototype of the Kilogram (IPK). It served as the mass standard for a long time until the most recent re - definition based on fundamental physical constants.

Answer:

A. a cylinder of platinum - iridium alloy