MEDIUM
JEE Main
IMPORTANT
Earn 100

The electronic configurations of bivalent europium and trivalent cerium are:
(atomic number: Xe=54 , Ce=58 , Eu=63)

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Important Questions on Classification of Elements and Periodicity in Properties

EASY
JEE Main
IMPORTANT
When the first electron gain enthalpy (ΔHeg) of oxygen is -141 kJ/mol , its second electron gain enthalpy is:
EASY
JEE Main
IMPORTANT
In general, the properties that decrease and increase down a group in the periodic table, respectively, are :
MEDIUM
JEE Main
IMPORTANT
The element having the greatest difference between its first and second ionization energies, is
MEDIUM
JEE Main
IMPORTANT
In the following sets of reactants which two sets best exhibit the amphoteric character of Al2O3 . xH2O ?

Set I Al 2 O 3 · xH 2 O s + OH aq - Set II Al 2 O 3 x · H 2 O s + H 2 O l Set III Al 2 O 3 x · H 2 O s + H aq + Set IV Al 2 O 3 · xH 2 O s + NH 3 aq
EASY
JEE Main
IMPORTANT
For the following Assertion and Reason, the correct option is:
Assertion: For hydrogenation reactions, the catalytic activity increases from Group 5 to Group 11 metals with maximum activity shown by Group 7-9 elements.
Reason: The reactants are most strongly adsorbed on group 7-9 elements.
MEDIUM
JEE Main
IMPORTANT
The first ionization energy (in kJ/mol ) of Na, Mg, Al and Si respectively are: