Classification of Elements and Periodicity in Properties
Test 15

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following elements has the lowest melting point?

Melting point decreases down group 1 due to weaker metallic bonding. Cs (group 1, period 6) has the lowest melting point among Li, Na, and Cs.

Li
Na
K
Cs
4

Which d-block element in period 5 has the highest electronegativity?

In period 5 d-block (Y to Cd), electronegativity increases across. Pd (group 10) has the highest electronegativity due to its position and nuclear charge.

Y
Zr
Nb
Pd
4

Which element has the ground state electronic configuration \(1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 4s^2\)?

This configuration (Z=28) corresponds to Ni (period 4, group 10), with \(3d^8 4s^2\), distinguishing it from Fe (\(3d^6 4s^2\)), Co (\(3d^7 4s^2\)), or Cu (\(3d^{10} 4s^1\)).

Fe
Ni
Co
Cu
2

Which element in group 16 has the highest tendency to exhibit a +6 oxidation state?

The +6 oxidation state is most stable for S (e.g., in \(\ce{SO3}\)) due to its balance of size and electronegativity, unlike O, Se, or Te, where it’s less common or stable.

O
Se
S
Te
3

Which group 15 element exhibits the maximum oxidation state of +5 in its compounds?

All group 15 elements can exhibit a +5 oxidation state, but N achieves it most prominently (e.g., in \(\ce{HNO3}\)) due to its small size and high electronegativity, unlike P, As, or Sb.

N
P
As
Sb
1

Which oxide of a group 17 element is the most stable in its highest oxidation state?

Stability of group 17 oxides in high oxidation states increases down the group. \(\ce{I2O5}\) (I, +5) is the most stable, unlike \(\ce{F2O}\), \(\ce{Cl2O7}\), or \(\ce{BrO3}\).

\(\ce{F2O}\)
\(\ce{I2O5}\)
\(\ce{Cl2O7}\)
\(\ce{BrO3}\)
2

Which element has the ground state electronic configuration \(1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 4s^1\)?

This configuration (Z=24) corresponds to Cr, an exception due to the stability of half-filled \(3d^5\), unlike Mn (\(3d^5 4s^2\)), Fe (\(3d^6 4s^2\)), or Co (\(3d^7 4s^2\)).

Mn
Cr
Fe
Co
2

Which ion among the following isoelectronic species with 36 electrons has the highest lattice energy when paired with \(\ce{F^-}\)?

For isoelectronic species (36 electrons), lattice energy increases with charge. \(\ce{Sc^3+}\) (Z=21, +3) forms \(\ce{ScF3}\) with the highest lattice energy compared to \(\ce{K+}\), \(\ce{Ca^2+}\), or \(\ce{Br^-}\).

\(\ce{Sc^3+}\)
\(\ce{K+}\)
\(\ce{Ca^2+}\)
\(\ce{Br^-}\)
1

Which element has the highest first ionization enthalpy among group 13 elements?

First ionization enthalpy decreases down a group. Among B, Al, Ga, and Tl (group 13), B (period 2) has the highest value.

Al
Ga
Tl
B
4

Arrange F, Cl, Br in order of decreasing electron gain enthalpy (most negative to least negative).

Electron gain enthalpy becomes less negative down group 17 due to increasing size. Order: Cl (most negative) > F > Br.

Note: F has less negative value than Cl due to electron repulsion in its smaller 2p orbital.

F > Cl > Br
Cl > F > Br
Br > F > Cl
Cl > Br > F
2

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