Which of the following is most stable?

What is the source of obtaining oxygen industrially?

Which of the following element is most reactive?

Which of the following is incorrect about Hypophosphorous acid?

Which of the following is the displays the most basic nature in water?

Which is the correct statement regarding halogens?

What temperature does dinitrogen oxide dissociate at?

In contact process, arsenic impurity has to be removed before proceeding.