sochatte, For Q-1 -
Obviously here we will go for the sentences starting with AS not by LIKE.
The option you have chosen is - C - is having the subject Hydrogen. First of all it uses passive voice and if you clearly look into the sentence construction it is saying that Hydrogen will explode - which is not the case.
Option - D is also having the same problem - subject problem.
Where E is not having such issues. So IMO E.
For Q-2 -
Ohhhhhh! Same Qs like the previous one. May be a wrong upload - u can say!