Multiple Choice QuestionsDue to the presence of an unpaired electron free radicals are
cations
anions
chemically inactive
chemically reactive
Ionic radii are
inversely proportional to effective nuclear charge
inversely proportional to square of effective nuclear charge
directly proportional to effective nuclear charge
directly proportional to square of effective nuclear charge
Which one of the following arrangements represents the correct order of electron gain enthalpy (with negative sign) of the given atomic species ?
Cl < F < S < O
O < S < F < Cl
S < O < Cl < F
F < Cl < O < S
Among NH3, HNO3, NaN3 and Mg3N2 the number of molecules having nitrogen in negative oxidation state is
1
2
3
4
Oxygen and sulphur both are the member of same group in periodic table but H2O is liquid while H2S is gas because
molecular weight of water is more
electronegativity of sulphur is more
H2S is weak acid
water molecules are having weak hydrogen bonds between them
The pair of elements having approximately equal ionisation potential is
Al, Ga
Al, Si
Al, Mg
Al, B
A.
Al, Ga
Ionisation energy increases with decrease in atomic size and decrease in shielding effect.
The electronic configuration of Al and Ga are
Al(13)= 1s2, 2s2, 2p6, 3s2, 3p1
Ga(31) =1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s2, 4p1
As the electronic configuration shows there are ten d-electrons in Ga which shield the nuclear charge less effectively than the s and p electrons. Hence, the outer electron is held fairly strongly by the nucleus. Consequently, ionisation energy slightly increases inspite of the increase in atomic size from Al to Ga. Hence, Al (IE= 577) and Ga (IE= 578) have approximately equal ionisation potential (or ionisation energy).
On adding 1 g arsenic to 80 g benzene, the freezing' point of benzene is lowered by 0.19°C. The formula of arsenic is
As
As2
As3
As4
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