Question: why caso4 is called acidic salt?
Answer: It is a salt of a strong acid ( H2SO4) and strong base ( Ca(OH)2 ). ... It's slightly basic because H2SO4 is a strong acid but HSO4(-) isn't: the bisulphate ion has a measurable acidity constant, albeit comparatively large. Thus the sulphate ion SO4(=) is a weak base.