Consider, $$\mathrm{PF}_{5}, \mathrm{BrF}_{5}, \mathrm{PCl}_{3}, \mathrm{SF}_{6},\left[\mathrm{ICl}_{4}\right]^{-}, \mathrm{ClF}_{3}$$ and $$\mathrm{IF}_{5}$$.

Amongst the above molecule(s)/ion(s), the number of molecule(s)/ion(s) having $$\mathrm{sp}^{3}\mathrm{~d}^{2}$$ hybridisation is __________.

$$1.80 \mathrm{~g}$$ of solute A was dissolved in $$62.5 \mathrm{~cm}^{3}$$ of ethanol and freezing point of the solution was found to be $$155.1 \mathrm{~K}$$. The molar mass of solute A is ________ g $$\mathrm{mol}^{-1}$$.

[Given : Freezing point of ethanol is 156.0 K.

Density of ethanol is 0.80 g cm^$$-$$3.

Freezing point depression constant of ethanol is 2.00 K kg mol^$$-$$1]

For a cell, $$\mathrm{Cu}(\mathrm{s})\left|\mathrm{Cu}^{2+}(0.001 \,\mathrm{M}) \| \mathrm{Ag}^{+}(0.01 \,\mathrm{M})\right| \mathrm{Ag}(\mathrm{s})$$

the cell potential is found to be $$0.43 \mathrm{~V}$$ at $$298 \mathrm{~K}$$. The magnitude of standard electrode potential for $$\mathrm{Cu}^{2+} / \mathrm{Cu}$$ is _________ $$\times 10^{-2} \mathrm{~V}$$.

[Given : $$E_{A{g^ + }/Ag}^\Theta $$ = 0.80 V and $${{2.303RT} \over F}$$ = 0.06 V]

Assuming $$1 \,\mu \mathrm{g}$$ of trace radioactive element X with a half life of 30 years is absorbed by a growing tree. The amount of X remaining in the tree after 100 years is ______ $$\times\, 10^{-1} \mu \mathrm{g}$$.

[Given : ln 10 = 2.303; log 2 = 0.30]