I remember learning in my tenth grade about Cation test using Sodium Hydroxide and Ammonia Solution (I mean these tests http://spmchemistry.blog.onlinetuition.com.my/2012/08/identifying-cations-test-with-sodium-hydroxide-and-ammonia-solution.html) But now in 12th grade we have been taught using original solution and group Analysis. What is the difference between the two? Group Analysis has more advantages, I think. If so, what are they? And if group Analysis is used everywhere then what is the use of those previous tests?