Give reasons for the following observations:
(i) SF6 is not easily hydrolysed though thermodynamically it should be.
(ii) Sulfur in vapour state exhibits paramagnetism.
(iii) `OF_6` is not known whereas, `SF_6` is known.
(iv) HCIO is a stronger acid than HIO.
(v) HCIO is a weaker acid than `HCIO_2`

Assign a reason for each of the following statements : (i) Ammonia is a stronger base than phosphine. (ii) Sulphur in vapour state exhibits a paramagnetic behaviour.

(a) Account for the following observations : (i) SF_(4) is easily hydrolysed whereas SF_(6) is not easily hydrolysed. (ii) Chlorine water is a powerful bleaching agent. (iii) Bi (V) is a stronger oxidising agent than Sb(V) (b) What happens when : (i) White phosphorus is heated with concentrated NaOH solution in an inert atmosphere of CO_(2). (ii) XeF_(6) undergoes partial hydrolysis. (Give the chemical equations involved).

Give reasons for the following observations : Why SF_(4) undergoes hydrolysis but not SF_(6) ? Or SF_(6) is inert towards hydroysis. SF_(6) is much less reactive than SF_(4) . Or (i) SF_(4) is easily hydrolysed whereas SF_(6) is not easily hydrolysed. (ii) Sulpher exhibits greater tendency for calenation than selenium. (iii) Sulpher has a higher tendency for catenation than oxygen.

Assign appropriate reasons for each of the following statements. (i)More metal fluorides are ionic in nature than metal chlorides. (ii) Hydrogen fluoride is a weaker acid than hydrogen chloride in aqueous solution. (iii)In aqueous solution HI is a stronger acid than HCI ? (iv) Addition of Cl_(2) to KI solution gives it a brown colour but excess of Cl_(2) turns it colourless. (v) Perchloric acid is a stronger acid than sulphuric acid.

Explain the following observations : (i) Fluorine does not exhibit any positive oxidation state. (ii) The majority of known noble gas compounds are those of Xenon. (iii) Phosphorus is much more reactive than nitrogen.

(A) Suggest a possible reason for the following observation: (i) In the solid state, PC l_(5) behaves as an ionic species. (ii) H_(2)S is more acidic than water. (iii) Fluorine forms the largest number of inter halogen compounds amongst the halogens.

(a) Draw the structure of the following : (i) N_(2)O_(5) (ii) XeOF_(4) (b) Explain the following observations : (i) The electron gain enthalpy of sulphur atom has a greater negative value than that of oxygen atom. (ii) Nitrogen does not form pentahalides. (iii) In an aqueous solution, HI is a stronger acid than HCl.

Assign a reason for each of the following : (I) SCl_(6) is not known but SF_(6) is known. (ii) Sulpher hexafluoride is used as a gaseous electrical insulater.

Account for the following observations (a) AlCl_(3) is a Lewis acid (b) Though fluorine is more electronegative than chlorine yet BF_(3) is a weaker Lewis acid than BCI_(3) (c) PbO_(2) is a stronger oxidising agent than SnO_(2) (d) The +1 oxidation state of thallium is more stable than its +3 state.

Which of the following sentences are staements? Justify your answer: (i) 9 is greater than 6. (ii) There is rain with clouds. (iii) Every set is an infinite set. (iv)The distance between delhi and kolkata is 735km. (v) the moon is a satellite. (vi) it is not a good day today.