Technically it's grp 1 elements...the answer is ribidium Rb
A covalent bond? Not sure how much detail you want, sorry
With a pH of five, it would mean that this substance is a weak acid one would also it expect it would be sour.
Weighs 0.001836 gram per cubic centimeter or 1.836 kilogram per cubic meter
Try to see if this helps
The volume of H₂ evolved at NTP=0.336 L
<h3>Further explanation</h3>
Reaction
Decomposition of NH₃
2NH₃ ⇒ N₂ + 3H₂
conservation mass : mass reactants=mass product
0.28 NH₃= 0.25 N₂ + 0.03 H₂
2 g H₂ = 22.4 L
so for 0.03 g :