Hydrogen Test - 5

The electronic configuration of hydrogen is such that it can acquire a stable electronic configuration either by losing one electron like the alkali metals or by gaining one electron like the halogens. Hence, hydrogen shows resemblance in its properties with both alkali metals as well as halogens.
Therefore, its position in the periodic table is debatable.

Nascent hydrogen has one unpaired electron in its valence shell. So, it is very reactive and undergoes several reactions to make a variety of compounds.

Cu + HCl will not produce H₂ since Cu is placed below hydrogen in the activity series.

GeH₂ is a methylene analogue and is not well characterised. It has been stabilised in complexes and this indicates that it is a covalent molecule. The best characterised hydride of germanium is GeH₄ (germane), and related Ge_nH_{2n + 2} alkane analogues, where n = 2 - 5. These all are covalent molecules.

Sodium hydride is the conjugate base of the extremely weak acid hydrogen (H₂) and is a very powerful base. It reacts with water in the following manner:
NaH + H₂O → NaOH + H₂ (g)
The base H^- competes very successfully with OH^- for protons and goes to completion because H₂ is about 10¹⁴ times weaker an acid than H₂O, meaning H^- is 10¹⁴ times stronger a base than OH^- and will pull a proton away from it with ease, causing release of H₂ that may ignite and a solution of NaOH of very high pH >13.

BaH₂ is an ionic hydride whereas SiH₄ is an interstitial hydride.

The transition metals and inner transition metals form a large variety of compounds with hydrogen which are non-stoichiometric. In the titanium family, titanium (Ti), zirconium (Zr) and hafnium (Hf) form non-stoichiometric hydrides when they absorb hydrogen and release heat. These hydrides have a chemical reactivity similar to that of the finely divided metal itself, being stable in air at ambient temperature but reactive when heated in air or with acidic compounds.

Statements a, b and c are correct.
(1) Metallic hydrides are deficient in hydrogen and are almost always non-stoichiometric. The composition of these hydrides does not correspond to simple whole number ratio and also varies with change in temperature and pressure and hence, these hydrides are called non-stoichiometric hydrides.
(2) Metallic hydrides are conductors of heat and electricity and are harder than the parent metal.

1 L of 1 M solution of H₂O₂ contains 34 g of H₂O₂.
1 L of 3 M solution of H₂O₂ contains 3 x 34 = 102 g of H₂O₂.