The boron hydride (also called diborane, B2H6) is not obtained by the direct reaction of hydrogen and boron; other methods are used.
You get a mixture of hydrogen and xenon.
It gets softer.
h
Hydrogen, H2, and a salt are formed.
B(HSO4)3 Boron bisulphate aka boron hydrogen sulphate.
You get a mixture of hydrogen and xenon.
water
It gets softer.
h
Iodine crystals
BOOM.
Hydrogen, H2, and a salt are formed.
Uranium, boron, hydrogen are chemical elements. Salt (NaCl) is a chemical compound.
B(HSO4)3 Boron bisulphate aka boron hydrogen sulphate.
Neptunium react with hydrogen forming hydrides with formulas between NpH2 and NpH3.
You just get a gas mixture of argon and hydrogen. Being less dense, the hydrogen will rise above the argon.
Nothing will happen. Helium is completely nonreactive.