Classification of Elements and Periodicity in Properties
Test 3

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which ion among the following isoelectronic species with 36 electrons has the largest radius?

For isoelectronic species (36 electrons), radius increases with decreasing nuclear charge. \(\ce{Br^-}\) (Z=35) has the largest radius compared to \(\ce{K+}\), \(\ce{Ca^2+}\), or \(\ce{Sc^3+}\).

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

Which group contains only p-block elements?

p-block spans groups 13–18. Options: (1) Na (group 1), Mg (group 2) → s-block; (2) B (group 13), C (group 14) → p-block; (3) Li (group 1), Be (group 2) → s-block; (4) K (group 1), Ca (group 2) → s-block.

Na, Mg
B, C
Li, Be
K, Ca
2

Which element in the fifth period has the highest electronegativity among p-block elements?

In period 5 p-block (Rb to Xe), electronegativity increases across. I (group 17) has the highest electronegativity among Sn, Sb, and I, excluding noble gases.

Sn
Sb
I
Xe
3

Which group 16 element has the highest tendency to form stable compounds in the +4 oxidation state?

The +4 oxidation state is most stable for S in group 16, forming \(\ce{SO2}\) (gaseous, strong S=O bonds), more stable than \(\ce{O2}\), \(\ce{SeO2}\) (polymeric), or \(\ce{TeO2}\) (solid).

A. Se
B. O
C. S
D. Te
3

Which element has the electronic configuration \(1s^2 2s^2 2p^6 3s^2 3p^2\)?

Total electrons = 14, corresponding to Si (period 3, group 14). Others: Al (13 electrons), P (15 electrons), Mg (12 electrons).

Al
Si
P
Mg
2

Which group 17 element exhibits the least reactivity with hydrogen due to its bond strength?

Reactivity with hydrogen decreases down group 17 as H-X bond strength weakens. F forms the strongest H-F bond, making \(\ce{HF}\) the least reactive among HF, HCl, HBr, and HI.

F
Cl
Br
I
1

Which ion among the following has the highest effective nuclear charge for an isoelectronic series with 10 electrons?

For isoelectronic species (10 electrons), effective nuclear charge increases with atomic number. \(\ce{Al^3+}\) (Z=13) has the highest effective nuclear charge compared to \(\ce{Na+}\), \(\ce{Mg^2+}\), or \(\ce{F^-}\).

\(\ce{Al^3+}\)
\(\ce{Na+}\)
\(\ce{Mg^2+}\)
\(\ce{F^-}\)
1

The atomic radius of which element is the largest among the following?

Atomic radius decreases across a period and increases down a group. Among F, Cl, Br, and I (group 17), Iodine (I), being lowest in the group, has the largest atomic radius.

I
F
Cl
Br
1

Which element in the fourth period has the highest metallic character?

Metallic character decreases across a period and increases down a group. In period 4, K (group 1) has the highest metallic character compared to Ca, Sc, or Ti.

Ca
Sc
Ti
K
4

Which pair of elements from different groups shows the closest similarity in ionization enthalpy?

Diagonal relationships reduce ionization enthalpy differences. Be (group 2, period 2) and Al (group 13, period 3) have similar values due to size and charge effects, unlike other pairs.

Li, Mg
Be, Al
B, Si
C, P
2

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