Question

Why does water expands on heating??

Answer 1

Water is an unusual liquid and has unique properties, but it doesn’t behave the exact opposite of other liquids.
Water does indeed expand when warms, and it contracts when it cools, but not at all temperatures.
An oddity occurs between 4 and 0 degrees Celsius (about 40 and 32 degrees Fahrenheit). As water cools from 4 to 0 degrees Celsius, it expands because it’s crystallizing into ice.
And as water warms from 0 to 4 degrees Celsius, it shrinks. But only within this range. Then it starts to expand again.