The plot of square root of frequency of X-ray emitted against atomic number led to suggestion of which law/rule?
Periodic law
Modern periodic law
Hund's rule
Newland's law
Which of the following represents the correct order of increasing first ionisation enthalpy for Ca, Ba, S, Se and Ar?
Ca <S<Ba<Se<Ar
S< Se<Ca<Ba< Ar
Ba< Ca<Se< S< Ar
Ba< Ca<Se< S< Ar
The first ionisation potential of Na is 5.1 eV. The value of electron gain enthalpy of Na+ will be
-2.55 eV
-5.1 eV
-10.2 eV
-10.2 eV
B.
-5.1 eV
Na → Na+ + e- (first IE)
Na+ + e- →Na
Since reaction is reverse, so electron gain enthalpy of Na+
ΔH (eg)=-5.1 eV
The increasing order of the ionic radii of the given isoelectronic species is
Cl-, Ca2+, K+, S2-
S2-, Cl-, Ca2+,K+
Ca2+, K+, Cl-, S2-
Ca2+, K+, Cl-, S2-
The outer electron configuration of Gd (Atomic No : 64) is
4f3 5d5 6s2
4f8 5d0 6s2
4f4 5d4 6s2
4f4 5d4 6s2
The correct sequence which shows decreasing order of the ionic radii of the elements is
Al3+ > Mg2+ > Na+ > F- > O2-
Na+ > Mg2+ > Al3+ > O2- > F-
Na+ > F- > Mg2+ > O2- > Al3+
Na+ > F- > Mg2+ > O2- > Al3+
The set representing the correct order of ionic radius is
Li+> Be2+> Na+> Mg2+
Na+>Li+>Mg2+> Be2+
Li+>Na+ > Mg2+ > Be2+
Li+>Na+ > Mg2+ > Be2+
The charge/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizing power of the cationic species, K+, Ca2+, Mg2+, Be2+?
Mg2+ < Be2+ < K+ < Ca2+
Be2+ < K+ < Ca2+ < Mg2+
K+ < Ca2+ < Mg2+ < Be2+
K+ < Ca2+ < Mg2+ < Be2+
The increasing order of the first ionization enthalpies of the elements B, P, S and F (lowest first) is
F < S < P < B
P < S < B < F
B < P < S < F
B < P < S < F