Page 12 - Finalll Science BB Prep2 t1 2025_Neat

• Every pure substance has fixed melting and boiling points at

normal atmospheric pressure

Melting point:

Temperature at which matter begins to change from solid to liquid.

Boiling point:

Temperature at which matter starts to change from liquid to gas.

1- Atmospheric pressure

As altitude
increases • Atmospheric
"above sea pressure
decreases
level"

Boiling point • As
of water temperature
decreases than decreases
100ºC 1º C / 300 m

Melting point of
ice and freezing
point of water
increases above
0º C

As altitude increases, Atmospheric pressure decreases,
boiling point decreases & melting point increases.

First Term 21