50 mL of 0.2 M ammonia solution is treated with 25 mL of 0.2 M HCl. If pK_b of ammonia solution is 4.75, the pH of the mixture will be :

The electron in the hydrogen atom undergoes transition from higher orbitals to orbital of radius 211.6 pm. This transition is associated with :

To find the standard potential of M³⁺/M electrode,the following cell is constituted : Pt/M/M³⁺(0.001 mol L⁻¹ )/Ag⁺(0.01 mol L⁻¹ )/Ag

The emf of the cell is found to be 0.421 volt at 298 K. The standard potential of half reaction M3⁺ + 3e⁻$$ \to $$ M at 298 K will be :

(Given $$E_{A{g^ + }\,/\,Ag}^ - $$ at 298 K = 0.80 Volt)

What quantity (in mL) of a 45% acid solution of a mono-protic strong acid must be mixed with a 20% solution of the same acid to produce 800 mL of a 29.875% acid solution ?