Ionisation energy in group 1A varies in the decreasing order as
Li > Na > K > Cs
Na > Li > K > Cs
Li > Cs > K Na
K > Cs > Na > Li
The equation used to represents the electron gain enthalpy is
X(g) + e- → X-(g)
X(s) + e- → X-(g)
X(g) → X+(g) + e-
X(s) → X+(g) + e-
An element in +2 oxidation state has 24 electrons. The atomic number of the element and the number of unpaired electrons in it respectively are
24 and 4
26 and 4
24 and 2
26 and 5
Among the following, the isoelectronic specie (s) is/are
(i) O2-, F-, Na+, Mg2+
(ii) Na+, Mg+, Al3+, F-
(iii) N3-, O2-, F-, Ne
(i) and (ii)
(i), (ii) and (iii)
(ii) and (iii)
(i) and (iii)
What is the atomic number of the element with symbol Uus?
117
116
115
114
A.
117
The atomic number of the element Uus is 117. Ununseptium (Uus) is the second heaviest known element and penultimate element of the 7th period of the periodic table.
Electronic configuration of Uus = [Rn]5f146d107s27p5
The increasing order of the first ionisation enthalpies of the elements B, P, S and F is
B < S < P < F
F < S < P < B
P < S < B < F
B < P < S < F
The electronic configuration of 59Pr ( praseodimium) is
[54Xe] 4f25d16s2
[54Xe] 4f15d16s2
[54Xe] 4f36s2
[54Xe] 4f35d2
The size of the iso-electronic species Cl-, Ar and Ca2+ is affected by:
nuclear charge
Prinicpal quantum number of valence shell
azimuthal quantum number of valence shell
electron-electron interaction in the outer orbitals