Multiple Choice QuestionsIn silica (SiO2), each silicon atom is bonded to
two oxygen atoms
four oxygen atoms
one silicon and two oxygen atoms
one silicon and four oxygen atoms
The magnetic nature of boron molecule is same as the magnetic nature of
nitrogen molecule
carbon molecule
unipositive nitrogen molecule
oxide ion
Which of the following is not a true alum?
Na2SO4.Al2(SO4)3.24H2O
MgSO4.Cr2(SO4)3.24H2O
K2SO4.Cr2(SO4)3.24H2O
(NH4)2SO4.Fe(SO4)3.24H2O
The densities of graphite and diamond at 298 K are 2.25 and 3.31 g cm-3 respectively. If the standard free energy difference is 1895 J mol-1, the pressure at which graphite will be transformed into diamond is
9.92 × 108 Pa
9.92 × 107 Pa
9.92 × 106 Pa
None of these
Which one of the following elements does not form triiodide on reacting with iodine?
B
Ti
Al
Ga
B.
Ti
Boran show consistently +3 oxidation state in its compounds while rest of the elements show +1 as well as +3 oxidation states. The +1 oxidation state becomes more and more stable as we move down the group, i.e
Al < Ga < In < Ti
Thus is due to the presence of intervening d- and f-orbitals which do not shield the nucleus effectively. Consequently effective nuclear charge increases, that holds the ns-electrons tightly so that they do not participate in bonding(inert pair effect).
Due to inert pair effect, Ti in +1 oxidation state is more stable than that of +3 oxidation state.
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