31 Year NEET Previous Year Questions: Hydrogen (Old NCERT) - NEET MCQ

Tritium (₁³H or T) This isotope of hydrogen is radioactive and emits low energy β-particle.
It has one proton and two neutrons in the nucleus. The concentration of tritium is very low.
It is just about one atom per 10¹⁸ atoms of protium.

Na produces golden yellow color with smokeless flame of Bunsen burner. Yellow is the characteristic color of Sodium.

Copper does not evolve H₂ from acid as it is below hydrogen in electro chemical series.

In this reaction H^– acts as bronsted base as it accepts one proton (H⁺) from H₂O and for H₂.

OR

In this reaction H−H- accepts H+H+ and as such acts as a base, H2OH2O gives H+H+ and as such acts as an acid.

Volume strength = 5.6 × Normality = 5.6 × 1.5 = 8.4 L

Temporary hardness is due to presence of bicarbonates of calcium and magnesium and permanent hardness is due to the sulphates or chlorides of both of calcium and magnesium.

O – O – H bond angle in H₂O₂ is 97°

Electrostatic forces of attraction are reduced to 1/80th in water.

In the structure of ice each molecule of H₂O is surrounded by three H₂O molecules in hexagonal honey comb manner. On the other in water, each molecule is surrounded by four neighbouring molecules randomly which results an open cage like structure. As a result there are a number of 'hole' or open spaces.
In such a structure lesser number of molecules are packed per ml. When ice melts a large no. of hydrogen bonds are broken.
The molecules therefore move into the holes or open spaces and come closer to each other than they were in solid state. This result sharp increase in the density. Therefore ice has lower density than water.

The complex salt of metaphosphoric acid sodium hexametaphosphate (NaPO₃)₆, is known as calgon. It is represented as Na₂[Na₄(PO₃)₆]

In this reaction H₂S is oxidised to sulphur and H₂O₂ is reduced to H₂O, hence this reaction show oxidation-reduction both i.e., redox reaction.