Aqueous solutions of Na$$_2$$S$$_2$$O$$_3$$ on reaction with Cl$$_2$$ gives:

Native silver metal forms a water soluble complex with a dilute aqueous solution of NaCN in the presence of:

Under the same reaction conditions, initial concentration of 1.386 mol dm$$^{-3}$$ of a substance becomes half in 40 seconds and 20 seconds through first order and zero order kinetics, respectively. Ratio $$\left( {{{{k_1}} \over {{k_0}}}} \right)$$ of the rate constants for first order ($$k_1$$) and zero order ($$k_0$$) of the reactions is:

2.5 mL of $$\frac{2}{5}$$M weak monoacidic base (K$$_b$$ = 1 $$\times$$ 10$$^{-12}$$ at 25$$^\circ$$C) is titrated with $$\frac{2}{15}$$M HCl in water at 25$$^\circ$$C. The concentration of H$$^+$$ at equivalence point is (K$$_w$$ = 1 $$\times$$ 10$$^{-14}$$ at 25$$^\circ$$C).