Hydrogen and s-Block Elements
(a) It produces less pollutants than petrol.
(b) A cylinder of compressed dihydrogen weighs ~30 times more than a petrol tank producing the same amount of energy.
(c) Dihydrogen is stored in tanks of metal alloys like NaNi5.
(d) On combustion, values of energy released per gram of liquid dihydrogen and LPG are 50 and 142 kJ, respectively.
|Column I||Column II|
|(i)||Na2CO3 . 10H2O||(A)||Portland cement ingredient|
(b) H2O2 + Ag2O → 2Ag + H2O + O2
Role of hydrogen peroxide in the above reactions is respectively:
The first ionisation potential of Na is 5.1 eV. The value of electron gain enthalpy of Na+ will be :
Assertion The mobility of sodium ion is lower than that of potassium ion.
Reason The ionic mobilities depend on the effective radius of the ion.
Assertion H2O2 under goes disproportionation on heating.
Reason It gives H2O and O2 on heating.
Assertion : K, Rb and Cs form superoxides.
Reason : The stability of the superoxides increases from 'K' to 'Cs' due to decrease in lattice energy.
Assertion : NaCl is less soluble in heavy water than in ordinary water.
Reason : Dielectric constant of ordinary water is more than that of heavy water.
Reason Smaller the radius of the hydrated cation, lower is the electrical conductance in aqueous solutions.
Reason In the presence of CoCl2, bleaching powder decomposes to give CaCl2 and O2.
STATEMENT-1: Alkali metals dissolve in liquid ammonia to give a blue solution.
STATEMENT-2: Alkali metals in liquid ammonia give solvated species of the type [M(NH3)n]+ (M = alkali metals).