Given

(i)   2Fe₂O₃(s) $$ \to $$ 4Fe(s) + 3O₂(g);

$$\Delta $$_rG^o = + 1487.0 kJ mol^-1

(ii)   2CO(g) + O₂(g) $$ \to $$ 2CO₂(g);

$$\Delta $$_rG^o = $$-$$ 514.4 kJ mol^-1

Free energy change, $$\Delta $$_rG^o for the reaction

2Fe₂O₃(s) + 6CO(g) $$ \to $$ 4Fe(s) + 6CO₂(g) will be :

The de-Broglie's wavelength of electron present in first Bohr orbit of 'H' atom is :

For per gram of reactant, the maximum quantity of N₂ gas is produced in which of the following thermal decomposition reactions ?
(Given : Atomic wt. - Cr = 52 u, Ba = 137 u)

If  a,   b,   c  are in A.P. and  a²,  b²,  c² are in G.P. such that
a < b < c and   a + b + c = $${3 \over 4},$$ then the value of a is :