273,15 K (0oC) and 100 kPa

the stratopause is the end of the stratosphere.

the stratosphere extends from a height of 10 km to 50 km above the surface of the Earth.

an acid that ionises completely, e.g. HCl, HNO3 and H2SO4

a base that ionises completely, e.g. NH3, NaOH.