21626.Which is the most thermodynamically stable allotropic form of phosphorus?
red
white
black
yellow
21627.Which of the following is arranged in the increasing order of enthalpy of vaporisation?
NH3, AsH3, PH3
AsH3, PH3, NH3
NH3, PH3, AsH3
PH3, AsH3, NH3
21628.Which compound has the maximum number of lone pair of electrons on the central atom?
[ClO3]–
XeF4
SF4
[I3]–
21629.In XeF2, XeF4, XeF6 molecules, the number of lone pairs of Xe are respectively
2, 3 and 1
1, 2 and 3
4, 1 and 2
3, 2 and 1
21630.Roasting of sulphides gives the gas X as a byproduct This is a colorless gas with choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic and acts as a reducing agent and its acid has never been isolated. The gas X is
SO2
CO2
SO3
H2S
21631.The correct IUPAC name for [CrF2(en)2]Cl is:
Chloro difluoridobis (ethylene diamine) chromium (III)
Chloro difluorido ethylene diaminechromium (III) chloride
Difluoridobis (ethylene diamine) chromium (III) chloride
Difluorobis–(ethylene diamine) chromium (III) chloride
21632.An element belongs to Group 15 and third period of the periodic table. Its electronic configuration will be
1s22s22p3
1s22s22p4
1s22s22p63s23p3
1s22s22p63s23p2
21633.Which statement is wrong?
Feldspars are not aluminosilicates
Beryl is an example of cyclic silicate
Mg2SiO4 is orthosilicate
Basic structural unit in silicates is the SiO4tetrahedron
21634.In froth floatation process for the purification of ores, the particles of ore float because
They are insoluble
They bear electrostatic charge
Their surface is not easily wetted by water
They are light
21635.When plants and animals decay, the organic nitrogen is converted into inorganic nitrogen. The inorganic nitrogen is in the form of _____.
Ammonia
Elements of nitrogen
Nitrates
Nitrides
21636.Excess of PCl5 reacts with conc. H2SO4 giving
chlorosulphonic acid
thionyl chloride
sulphuryl chloride
sulphurous acid
21637.The noble gas mixture is cooled in a coconut bulb at 173 K. The gases that are not adsorbed are
He and Ne
Ar and Kr
He and Xe
Ne and Xe
21638.What products are expected from the disproportionation reaction of hypochlorous acid?
HClO3 and Cl2O
HClO2 and HClO4
HCl and Cl2O
HCl and HClO3
21640.In the Dewar's method of separation of noble gases, the mixture of noble gases is kept in contact with coconut charcoal at 173 K. Which one of the following gaseous mixtures is not absorbed on to the charcoal?
Ar, Kr
Xe, Kr
He, Ne
Xe, Ar
21641.Which of the following statements regarding sulphur is incorrect?
The oxidation state of sulphur is never less than +4 in its compounds
S2 molecule is paramagnetic
The vapour at 200°C consists mostly of S8 rings
At 600°C the gas mainly consists of S2 molecules
21643.The brown ring test for nitrates depends on
reduction of ferrous sulphate to iron
oxidation of nitric oxide to nitrogen dioxide
the reduction of nitrate to nitric oxide
oxidising action of sulphuric acid
21644.Which of the following is used to prepare Cl2 gas at room temperature from concentrated HCl?
MnO2
H2S
KMnO4
Cr2O3