Which of the following methods is used for the removal of temporary hardness of water?

• Treatment with washing soda

• Calgon method

• lon-exchange method

• Clark's method

Temporary hardness of water is removed in Clark's process by adding

• caustic soda

• calgon

• borax

• lime

203.

Calgon is

• Na₂HPO₄

• Na₃PO₄

• Na₆P₆O₁₈

• NaH₂PO₄

On which of the following principles hydrogen bomb is based?

• Nuclear fission

• Nuclear fusion

• Artificial radioactivity

• Natural radioactivity

Radioactive hydrogen is

• tritium

• deuterium

• ortho hydrogen

• para hydrogen

H₂O₂ on oxidation gives

• O^2-

• OH^-

• O${}_2^{-}$

• O₂

The IE of hydrogen atom is 13.6 eV. The energy required to remove an electron in the n = 2 state of the hydrogen atom is

• 27.2 eV

• 13.6 eV

• 6.8 eV

• 3.4 eV

Hydrogen is prepared on large scale for industrial use

• by Zn + H₂SO₄

• by Al + NaOH

• by Na + C₂H₅OH

• from water gas

When conc. H₂SO₄ comes in contact with sugar, it becomes black due to 

• hydrolysis

• hydration

• decolourisation

• dehydration

The temperature of maximum density of H₂O and D₂O respectively are

• 0°C and 11.6°C

• 4°C and 0°C

• 4°C and 11.6°C

• 4°C and 12.5°C