For elements $$\mathrm{B}, \mathrm{C}, \mathrm{N}, \mathrm{Li}, \mathrm{Be}, \mathrm{O}$$ and $$\mathrm{F}$$, the correct order of first ionization enthalpy is

$$25 \mathrm{~mL}$$ of silver nitrate solution (1M) is added dropwise to $$25 \mathrm{~mL}$$ of potassium iodide $$(1.05 \mathrm{M})$$ solution. The ion(s) present in very small quantity in the solution is/are :

When a solution of mixture having two inorganic salts was treated with freshly prepared ferrous sulphate in acidic medium, a dark brown ring was formed whereas on treatment with neutral $$\mathrm{FeCl}_{3}$$, it gave deep red colour which disppeared on boiling and a brown red ppt was formed. The mixture contains :

Given below are two statements:

Statement I : If BOD is 4 ppm and dissolved oxygen is 8 ppm, then it is a good quality water.

Statement II : If the concentration of zinc and nitrate salts are $$5 ~\mathrm{ppm}$$ each, then it can be a good quality water.

In the light of the above statements, choose the most appropriate answer from the options given below :