Classification of Elements and Periodicity in Properties's Question 8 | Chemistry XI - Part 1 | NCERT Exemplar Questions

Physical Chemistry

Some Basic Concepts of Chemistry Structure of Atom States of Matter Thermodynamics Equilibrium

Inorganic Chemistry

Classification of Elements and Periodicity in Properties Chemical Bonding and Molecular Structure

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MCQ (Single Correct Answer)

The period number in the long form of the periodic table is equal to

magnetic quantum number of any element of the period

atomic number of any element of the period

maximum principal quantum number of any element of the period

maximum azimuthal quantum number of any element of the period

MCQ (Single Correct Answer)

The elements in which electrons are progressively filled in $4 f$-orbital are called

actinoids

transition elements

lanthanoids

halogens

MCQ (Single Correct Answer)

Which of the following is the correct order of size of the given species

I $>\mathrm{I}^{-}>\mathrm{I}^{+}$

$\mathrm{I}^{+}>\mathrm{I}^{-}>\mathrm{I}$

$\mathrm{I}>\mathrm{I}^{+}>\mathrm{I}^{-}$

$\mathrm{I}^{-}>\mathrm{I}>\mathrm{I}^{+}$

MCQ (Single Correct Answer)

The formation of oxide ion $0^{2-}(\mathrm{g})$, from oxygen atom requires first an exothermic and then an endothermic step as shown below

$$\begin{aligned} & \mathrm{O}(g)+e^{-} \rightarrow \mathrm{O}^{-}(g) ; \Delta H^{\mathrm{s}}=-141 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ & \mathrm{O}^{-}(g)+e^{-} \rightarrow \mathrm{O}^2(g) ; \Delta H^{\mathrm{s}}=+780 \mathrm{~kJ} \mathrm{~mol}^{-1} \end{aligned}$$

Thus, process of formation of $\mathrm{O}^{2-}$ in gas phase is unfavourable even though $\mathrm{O}^{2-}$ is isoelectronic with neon. It is due to the fact that

oxygen is more electronegative

addition of electron in oxygen results in larger size of the ion

electron repulsion outweighs the stability gained by achieving noble gas configuration

$\mathrm{O}^{-}$ion has comparatively smaller size than oxygen atom

MCQ (Single Correct Answer)

Comprehension given below is followed by some multiple choice questions. Each question has one correct option. Choose the correct option. In the modern periodic table, elements are arranged in order of increasing atomic numbers which is related to the electronic configuration. Depending upon the type of orbitals receiving the last electron, the elements in the periodic table have been divided into four blocks, viz $s, p, d$ and $f$.

The modern periodic table consists of 7 periods and 18 groups. Each period begins with the filling of a new energy shell. In accordance with the Aufbau principle, the seven periods (1 to 7 ) have $2,8,8,18$, 18,32 and 32 elements respectively.

The seventh period is still incomplete. To avoid the periodic table being too long, the two series of $f$-block elements, called lanthanoids and actinoids are placed at the bottom of the main body of the periodic table

(i) The element with atomic number 57 belongs to

s - block

p - block

d - block

f - block

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