Classification of Elements and Periodicity in Properties
Test 8

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which oxide among the following is basic?

Basic oxides are formed by metals, especially s-block elements. \(\ce{BaO}\) (group 2) is basic, unlike \(\ce{N2O5}\) (acidic), \(\ce{SiO2}\) (acidic), or \(\ce{Al2O3}\) (amphoteric).

\(\ce{N2O5}\)
\(\ce{BaO}\)
\(\ce{SiO2}\)
\(\ce{Al2O3}\)
2

Which of the following has the smallest atomic radius among group 15 elements?

Atomic radius increases down a group. Among N, P, As, and Sb (group 15), N (period 2) has the smallest radius.

P
N
As
Sb
2

Which element has a positive electron gain enthalpy?

Noble gases have positive electron gain enthalpies due to their stable configurations. Ne (group 18) requires energy to add an electron, unlike O, S, or Cl.

O
S
Ne
Cl
3

Which of the following elements exhibits variable valency due to d-orbital involvement?

d-block elements exhibit variable valency due to partially filled d-orbitals. Cu (group 11) shows this, unlike Na (s-block), Al (p-block), or Kr (p-block, full).

Cu
Na
Al
Kr
1

Which d-block element in period 4 forms a compound with oxygen exhibiting the highest oxidation state of +7?

In period 4 d-block (Sc to Zn), Mn (group 7) achieves a +7 oxidation state in \(\ce{Mn2O7}\), unlike Cr (+6), Fe (+3), or Co (+3).

Cr
Fe
Co
Mn
4

Which pair of elements belongs to the same period?

Elements in the same period have the same principal quantum number. Na (3s¹) and Al (3p¹) are in period 3, unlike the other pairs spanning different periods.

Li, Be
Na, Al
K, Ca
Na, K
2

Which element in group 1 has the lowest first ionization enthalpy?

First ionization enthalpy decreases down a group due to increased atomic size and shielding. Among Li, Na, K, and Cs, Cs (period 6) has the lowest value.

Cs
Li
Na
K
1

Which of the following elements has the highest electronegativity?

Electronegativity increases across a period and decreases down a group. Among Li, Be, N, and F, F (group 17, period 2) has the highest electronegativity due to its position on the far right of the periodic table.

F
Li
Be
N
1

Which element has the smallest ionic radius among the following cations?

For isoelectronic cations (\(\ce{Li+}\), \(\ce{Be^2+}\), \(\ce{B^3+}\), \(\ce{C^4+}\), all with 2 electrons), radius decreases with increasing nuclear charge. \(\ce{B^3+}\) (Z=5) is smaller than \(\ce{Li+}\) (Z=3), \(\ce{Be^2+}\) (Z=4), and \(\ce{C^4+}\) (Z=6).

\(\ce{Li+}\)
\(\ce{Be^2+}\)
\(\ce{C^4+}\)
\(\ce{B^3+}\)
4

Which element was predicted as Eka-aluminium by Mendeleev?

Mendeleev predicted Eka-aluminium below Al, later identified as Gallium (Ga), matching its properties like oxide formula \(\ce{Ga2O3}\).

Ge
Si
In
Ga
4

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