Guess Paper – 2009
Class – XII
Subject – CHEMISTRY
p-BLOCK ELEMENTS (GROUP-15 REASONING)
Q1 Give reasons:
i) Nitrogen exists as diatomic molecules whereas phosphorous exist as tetra atomic molecules. ii) Molecular nitrogen is not particularly reactive.
iii) NCl3 gets readily hydrolyzed while NF3 does not.
iv) Nitrogen does not form pent halides like phosphorous. v) Bond angle of ammonia is higher than phosphine.
vi) Ammonia is a good complexing agent.
vii) Though nitrogen exhibits +5 oxidation state, it does not form pentahalide. Give reason. viii) PH3 has lower boiling point than ammonia.
ix) H3PO3 is diprotic.
x) Unlike phosphorous, nitrogen shows little tendency for catenation. xi) Nitric acid cannot be used to prepare H2S
xii) Phosphine is prepared in inert atmosphere of carbon dioxide. xiii) Phosphorous pentaoxide is used in the preparation of N2O5. xiv) Red phosphorous is used for making matches.
xv) The electro negativity of both nitrogen and chlorine is the same. But nitrogen is inert at room temperature whereas chlorine is highly reactive. xvi) Pure PH3 does not burn but impure sample of PH3 burns in air xvii) Nitric acid turns yellow in sunlight.
xviii) Nitrate and nitrite cannot be distinguished by the action of concentrated H2SO4. xix) NO2 cannot be dried by means of NaOH solution.
xx) On heating Pb(NO3)2 produces a pale yellow gas which on strong heating produces a brown gas. xxi) Nitric acid mostly forms oxides of nitrogen on reacting with metals while other acids react with metals to evolve hydrogen. xxii) Burning magnesium continues to burn in nitric oxide while burning Sulphur extinguishes. xxiii) Phosphorous does not form phosphorous penta-iodide.
xxiv) Phosphorous acid is a dibasic acid.
xxv) (SiH3)3N is a weaker base than (CH3)3N.
xxvi) Mg3N2 when reacted with water gives off NH3 but HCl is not obtained from MgCl2 on reaction with...
Please join StudyMode to read the full document