Online Test — Classification of Elements and Periodicity in Properties

20 Questions • 15 min • Chapter MCQ

15:00

Question 1 of 20

The Modern Periodic Law is based on:

atomic mass

atomic number

atomic volume

number of neutrons

Explanation: Moseley established that properties are a periodic function of atomic number.

Question 2 of 20

Döbereiner classified elements into:

octaves

triads

periods

blocks

Explanation: Döbereiner grouped elements into triads with the middle mass near the mean of the other two.

Question 3 of 20

The number of periods in the long form periodic table is:

Explanation: There are 7 horizontal periods.

Question 4 of 20

Eka-aluminium predicted by Mendeleev is now known as:

scandium

gallium

germanium

technetium

Explanation: Eka-aluminium is gallium.

Question 5 of 20

An element with configuration $[\text{Ar}]3d^{10}4s^24p^5$ belongs to group:

Explanation: Valence electrons = 7, so group = 10 + 7 = 17 (a halogen).

Question 6 of 20

Which set is correctly ordered by increasing ionic radius?

$\text{Al}^{3+} < \text{Mg}^{2+} < \text{Na}^+ < \text{F}^-$

$\text{F}^- < \text{Na}^+ < \text{Mg}^{2+} < \text{Al}^{3+}$

$\text{Na}^+ < \text{Mg}^{2+} < \text{F}^- < \text{Al}^{3+}$

$\text{Mg}^{2+} < \text{Al}^{3+} < \text{Na}^+ < \text{F}^-$

Explanation: Isoelectronic: size decreases as $Z$ increases.

Question 7 of 20

First ionisation enthalpy across a period generally:

decreases

increases

is constant

is zero

Explanation: Rising $Z_{eff}$ and smaller size raise ionisation enthalpy across a period.

Question 8 of 20

The dip O

O being a metal

stable half-filled $2p^3$ in N

O being larger

higher $Z_{eff}$ in O

Explanation: Nitrogen's stable half-filled $2p^3$ raises its ionisation enthalpy above oxygen's.

Question 9 of 20

The most electronegative element is:

Explanation: Fluorine has the highest electronegativity (4.0 on the Pauling scale).

Question 10 of 20

Which oxide is amphoteric?

$\text{MgO}$

$\text{Al}_2\text{O}_3$

$\text{SO}_3$

$\text{Na}_2\text{O}$

Explanation: $\text{Al}_2\text{O}_3$ reacts with both acids and bases.

Question 11 of 20

A cation compared with its parent atom is:

larger

smaller

equal

unpredictable

Explanation: Loss of electrons (often a whole shell) and higher $Z_{eff}$ make a cation smaller.

Question 12 of 20

The block of the element with $Z=21$ (Sc) is:

Explanation: $[\text{Ar}]3d^14s^2$; the last electron enters $3d$, so it is d-block.

Question 13 of 20

The IUPAC name for the element with $Z=118$ root-based is:

ununoctium

unbinilium

ununennium

ununhexium

Explanation: Digits 1,1,8 give un-un-oct-ium = ununoctium.

Question 14 of 20

Metallic character down a group:

increases

decreases

is constant

becomes zero

Explanation: Ionisation enthalpy falls down a group, so metallic character increases.

Question 15 of 20

Nitrogen's maximum covalency is limited to 4 because it lacks:

$s$ orbitals

valence $d$ orbitals

$p$ orbitals

neutrons

Explanation: Second-period N has no valence $d$ orbitals, capping covalency at 4.

Question 16 of 20

Electron gain enthalpy of Cl is more negative than F because:

Cl is a metal

F's small shell gives high electron repulsion

Cl is larger and inert

F has higher $Z$

Explanation: F's compact $2p$ shell causes strong repulsion on adding an electron, so less energy is released than for Cl.

Question 17 of 20

Which element shows a diagonal relationship with aluminium?

boron

beryllium

carbon

magnesium

Explanation: Be shows a diagonal relationship with Al.

Question 18 of 20

The general valence configuration of the p-block is:

$ns^{1-2}$

$ns^2np^{1-6}$

$(n-1)d^{1-10}ns^{0-2}$

$(n-2)f^{1-14}$

Explanation: p-block elements have outer configuration $ns^2np^{1-6}$.

Question 19 of 20

The highest oxidation state of sulphur is:

Explanation: S is in group 16; its highest oxidation state is +6 (as in $\text{SO}_3$).

Question 20 of 20

Across period 3 the oxides change in the order:

acidic to basic

basic to acidic

all neutral

all amphoteric

Explanation: Oxides go basic to amphoteric to acidic as metallic character falls.

0 / 20

Test Complete!

Score

Correct

Wrong

0:00

Time

Back to Study All Chapters