Deuterium resembles hydrogen in properties but:

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?

Which of the following is expected to be high for a proton $(H^+)$?

Which of the following combinations represents water gas?

Which of the following is commonly used in a laboratory desiccator?

Out of the two allotropic forms of dihydrogen,the form with lesser molecular energy is