(i) Which allotrope of phosphorus is more reactive and why?.
(ii) How are the supersonic jet aeroplanes responsible for the depletion of ozone layer ?
(iii) `F_(2)` has lower bond dissociation epthalpy than `Cl_(2)`. Why?
(iv) Which noble gas is used in filling balloons for meteorological observations?
(v) Complete the following equation :
`XeF_(2)+PF_(5)rarr`

(a) Given reasons for the following : (i) Bond enthalpy of F_2 is lower than that of Cl_2 . (ii) PH_3 has lower boiling point than NH_3 . (b) Draw the structures of the following molecules : (i) BrF_3 (ii) (HPO_3)_3 (iii) XeF_4

(a) Which of these have higher bond dissociation energy and why ? (i) N_(2)^(+)(ii)O_(2)^(+) (b) What kinds of molecular forced exist between the species in the following pairs of particles and why ? (i)He and N_(2)(ii) Cl_(2)and NO_(3)^(-)(iii)NH_(3)and CO.

Which of the following observations can be explained on the basis of hydrogen bonding ? (i) H- F has higher boiling point than other halogen acids. (ii) H_(2) O has highest boiling point among hydrides of group 16 elements. (iii) NH_(3) has lower boiling point than PH_(3) .

Draw the diagram a of galvanic cell involving following reactions : Zn+Cu^(+) to Zn^(2+) +Cu and answer the following questions: (i) Label the cathode and anode (ii) How does the e.m.f. of the cell changes with the decrease in the concentration of Cu^(2+) ions ? (iii) What is the function of salt bridge in it? (iv) Name the salt to be used in salt bridge. (v) Write the reactions occurring at each electrode. (vi) In which direction the electrons would flow in the external circuit? (vii) How electrical neutrality is maintained in both the half cells?

(a) Following are the transition metal ions of 3d series: Ti^(4+),V^(2+),Mn^(3+),Cr^(3+) (Atomic numbers: Ti=22,V=23,Mn=25,Cr=24 ) Answer the following: (i) Which ion is most stable in an aqueous solution and why? (ii) Which ion is a strong oxidising agent and why? (iii) Which ion is colourless and why? (b) Complete the following equations: (i) 2MnO_(4)^(-)+16H^(+)+5S^(-)to (ii) KMnO_(4)overset(heat)to

A chemist opened a cupboard to find four bottles containing water solutions, each of which has lost its label. Bottles 1,2,3 contained colourless solutions, Whilst bottle 4 contained a blue solution. The labels from the bottles were lying scattered ont he floor of the cupboard. They were copper (II) sulphate sodium carbonate lead nitrate hydrochloric acid By mixing sammples of teh contents of the bottles, in pairs, the chemist made the following observations: (i) Bottle 1 + Bottle 2 white precipitate (ii) Bottle 1 + bottle 3 white precipitate (iii) Bottle 1 + Bottle 4 white precipitate (iv) Bottle 2 +Bottle 3 colourless gas evolved (v) Bottle 2+ Bottle 4 no visible reaction (vi) bottle 3 +bottle 4 blue precipitate Q. Nature of gas evolved in observation (iv) is:

in an ionic bond the cation tends to polarise the electron cloud of the anion by pulling electron density towards itself This causes development of covalent character in the ionic bond because the electron density gets localised in between the nuclei The tendency of the cation to bring about the polarisation of the anion is expressed as its polasising power The ability of ion to undergo polarisation is called its polarisability The polarising power of a cation or an anion is decided on the basis of F ajans' rules as follows . (i) The smaller the cation, the higher is its polarising power (ii) Cations with pseudo-noble gas configuration (ns^(2)np^(6)nd^(10)) have relatively high polarising power than those with noble gas configuration (ns^(2) np^(6)) (iii) The larger the size of the anion, the higher is its polarisability The ionic conductance of which of the following is the highest ? .

A chemist opened a cupboard to find four bottles containing water solutions, each of which has lost its label. Bottles 1,2,3 contained colourless solutions, Whilst bottle 4 contained a blue solution. The labels from the bottles were lying scattered ont he floor of the cupboard. They were copper (II) sulphate sodium carbonate lead nitrate hydrochloric acid By mixing sammples of teh contents of the bottles, in pairs, the chemist made the following observations: (i) Bottle 1 + Bottle 2 white precipitate (ii) Bottle 1 + bottle 3 white precipitate (iii) Bottle 1 + Bottle 4 white precipitate (iv) Bottle 2 +Bottle 3 colourless gas evolved (v) Bottle 2+ Bottle 4 no visible reaction (vi) bottle 3 +bottle 4 blue precipitate Q. Chemical formula of white ppt. formed in observation (iii) is:

A chemist opened a cupboard to find four bottles containing water solutions, each of which has lost its label. Bottles 1,2,3 contained colourless solutions, Whilst bottle 4 contained a blue solution. The labels from the bottles were lying scattered ont he floor of the cupboard. They were copper (II) sulphate sodium carbonate lead nitrate hydrochloric acid By mixing sammples of teh contents of the bottles, in pairs, the chemist made the following observations: (i) Bottle 1 + Bottle 2 white precipitate (ii) Bottle 1 + bottle 3 white precipitate (iii) Bottle 1 + Bottle 4 white precipitate (iv) Bottle 2 +Bottle 3 colourless gas evolved (v) Bottle 2+ Bottle 4 no visible reaction (vi) bottle 3 +bottle 4 blue precipitate Q. Chemical formula of white precipitate in observation (i) is:

A chemist opened a cupboard to find four bottles containing water solutions, each of which has lost its label. Bottles 1,2,3 contained colourless solutions, Whilst bottle 4 contained a blue solution. The labels from the bottles were lying scattered ont he floor of the cupboard. They were copper (II) sulphate sodium carbonate lead nitrate hydrochloric acid By mixing sammples of teh contents of the bottles, in pairs, the chemist made the following observations: (i) Bottle 1 + Bottle 2 white precipitate (ii) Bottle 1 + bottle 3 white precipitate (iii) Bottle 1 + Bottle 4 white precipitate (iv) Bottle 2 +Bottle 3 colourless gas evolved (v) Bottle 2+ Bottle 4 no visible reaction (vi) bottle 3 +bottle 4 blue precipitate Q. Colourless solution present in bottle-1 is: