Doubt from hydrogen

solved
hydrogen
hydrogen-properties
reactions
easy
pp
#1

#2

Answer is c
It is given in textbook

#3

Ok bro

#4

The correct answer will be 3) as in this the percentage purity of the H2 is around 99℅,and this method is mostly used in the industry,and for more details, you can refer the ncert textbook of class 11th,in S-block chapter.