Classification of Elements and Periodicity in Properties
Test 7

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which element in group 2 has the highest hydration enthalpy due to its ionic size?

Hydration enthalpy increases with smaller ionic size and higher charge density. Be²⁺ (smallest in group 2) has the highest hydration enthalpy compared to Mg²⁺, Ca²⁺, or Sr²⁺.

Be
Mg
Ca
Sr
1

What is the formula of the compound formed by magnesium and nitrogen?

Mg (group 2, valence 2) and N (group 15, valence 3) form \(\ce{Mg3N2}\) by cross-multiplying valences.

\(\ce{MgN}\)
\(\ce{Mg2N3}\)
\(\ce{Mg3N2}\)
\(\ce{MgN2}\)
3

Which element has the lowest first ionization enthalpy in the fifth period?

First ionization enthalpy decreases across a period from right to left. In period 5, Rb (group 1) has the lowest value compared to Sr, Ag, and I.

Sr
Ag
Rb
I
3

Which element in group 13 has the highest ionization enthalpy after losing two electrons?

Third ionization enthalpy is highest for B (removing an electron from \(\ce{B^2+}\) with \(1s^2\)) due to its small size and stable configuration, compared to Al, Ga, or In.

Al
Ga
B
In
3

How many elements are present in the fourth period of the periodic table?

The fourth period (\(n=4\)) includes \(4s\), \(3d\), and \(4p\) orbitals, accommodating 18 electrons, hence 18 elements (K to Kr).

8
10
18
32
3

What is the general outer electronic configuration of group 17 elements?

Group 17 elements (halogens) have 7 valence electrons, with outer configuration \(ns^2 np^5\).

\(ns^2 np^1\)
\(ns^2 np^3\)
\(ns^2 np^6\)
\(ns^2 np^5\)
4

Which of the following elements has the highest metallic character?

Metallic character increases down a group and decreases across a period. Among B, Al, Ga, and Tl, Tl (group 13, period 6) has the highest metallic character.

B
Al
Ga
Tl
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 atomic size. Cl has the most negative value due to optimal nuclear charge and size, followed by F (less negative due to electron repulsion in its compact 2p orbitals), then Br. Order: Cl > F > Br.

A. F > Cl > Br
B. Cl > F > Br
C. Br > F > Cl
D. Cl > Br > F
2

Arrange the following elements in order of increasing covalent radius: N, P, As, Sb.

Covalent radius increases down group 15 due to additional electron shells. Order: N < P < As < Sb.

Sb < As < P < N
N < P < As < Sb
P < N < As < Sb
As < Sb < N < P
2

Which element forms a neutral oxide?

Neutral oxides do not react with acids or bases. C (group 14) forms \(\ce{CO}\), a neutral oxide, unlike \(\ce{Na2O}\) (basic), \(\ce{P2O5}\) (acidic), or \(\ce{Al2O3}\) (amphoteric).

Na
C
P
Al
2

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