Nascent hydrogen consists of $-$

(1) Hydrogen atoms with excess energy

(2) Hydrogen molecules with excess energy

(3) Hydrogen ions in the excited state

(4) Solvated protons

Maximum concentration of ortho-$H_2$ in ordinary hydrogen is:

(1) 75% ortho-$H_2$ + 25% para-$H_2$

(2) 25% ortho-$H_2$ + 75% para-$H_2$

(3) 50% ortho-$H_2$ + 50% para-$H_2$

(4) 99% para-$H_2$ + 1% ortho-$H_2$

Hydrogen will not reduce$-$

(1) heated cupric oxide                                 

(2) heated ferric oxide

(3) heated stannic oxide                               

(4) heated aluminium oxide

Chemical A is used for water softening to remove temporary hardness. A reacts with sodium carbonate to generate caustic soda. When ${\mathrm{CO}}_2$ is bubbled through a solution of A, it turns cloudy. What is the chemical formula of A$-$

(1) ${\mathrm{CaCO}}_3$                             

(2) $\mathrm{CaO}$

(3) $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$                           

(4) $\mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2$

The first ionization energy value $\left(\mathrm{kJ}\right)$ ${\mathrm{mol}}^{-1}$ for $\mathrm{H},$ $\mathrm{Li},$ $\mathrm{F},$ $\mathrm{and}$ $\mathrm{Na}$ 

is given below but not in a correct order

$1681,$ $520,$ $1312,$ $495.$

The ionization energy value of H would be -

1. 1681                                 

2. 1312

3. 520                                   

4. 485

The hydrides ion ${\mathrm{H}}^{-}$ is a stronger base than its hydroxide ion ${\mathrm{OH}}^{-}$. Which of the following reactions will occur if sodium hydride $\left(\mathrm{NaH}\right)$ is dissolved in water –

(A) ${\mathrm{H}}^{-}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{H}}_3{\mathrm{O}}^{-}\left(\mathrm{aq}\right)$

(B) ${\mathrm{H}}^{-}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathcal{l}\right)\to {\mathrm{OH}}^{-}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

(C) ${\mathrm{H}}^{-}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathcal{l}\right)\to \mathrm{No} \mathrm{reaction}$

(D) $\mathrm{None} \mathrm{of} \mathrm{these}$

Blackened oil planting can be restored into original form by the action of:

1. Chlorine

2. ${\mathrm{BaO}}_2$

3. ${\mathrm{H}}_2{\mathrm{O}}_2$

4. ${\mathrm{MnO}}_2$

Which of the following statement regarding ${\mathrm{H}}_2{\mathrm{O}}_2$ is wrong.

(1) It is stable in acid medium

(2) It acts as oxidising as well as reducing agent

(3) It has zero dipole moment

(4) Pure ${\mathrm{H}}_2{\mathrm{O}}_2$ is slightly acidic

Polyphosphates are used as water softening agents because they –

(1) form soluble complexes with anionic species

(2) precipitate anionic species

(3) form soluble complexes with cationic species

(4) precipitate cationic species

The ortho and para hydrogen have –

(A) Same physical properties but different chemical properties

(B) Different physical properties but same chemical properties

(C) Same chemical and physical properties

(D) Different physical and chemical properties