Which of the hydrogen halides forms salts like $KHX_2$ (where $X$ is a halogen atom)?

Write a short note on Dihydrogen.

Deuterium resembles hydrogen in chemical properties but reacts:

Which of the following is used as a promoter in the Bosch process?

Describe the bulk preparation of dihydrogen by the electrolytic method. What is the role of an electrolyte in this process?

Consider the following statements:
$1.$ Atomic hydrogen is obtained by passing hydrogen through an electric arc.
$2.$ Hydrogen gas will not reduce heated aluminium oxide.
$3.$ Finely divided palladium adsorbs large volume of hydrogen gas.
$4.$ Pure nascent hydrogen is best obtained by reacting $Na$ with $C_2H_5OH$.
Which of the above statements is/are correct?