Classification of Elements and Periodicity in Properties - Online Test

Q1. f-block of the Periodic Table consists of
Answer : Option C
Explaination / Solution:

The two rows of elements at the bottom of the Periodic Table, called the Lanthanoids, Ce(Z = 58) – Lu(Z = 71) and Actinoids, Th(Z = 90) – Lr (Z = 103) are characterised by the outer electronic configuration (n-2)f1-14 (n-1)d0-1 ns2. The last electron added to each element is filled in f- orbital. These two series of elements are hence called the Inner- Transition Elements (f-Block Elements).

Q2. Metalloids show the properties of
Answer : Option C
Explaination / Solution:

A metalloid is any chemical element which has properties in between those of metals and nonmetals, or that has a mixture of them. Typical metalloids have a metallic appearance, but they are brittle and only fair conductors of electricity. Chemically, they behave mostly as nonmetals. They can form alloys with metals. Most of their other physical and chemical properties are intermediate in nature. The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium.

Q3. Which of the following statements is false?
Answer : Option B
Explaination / Solution:

The elements of Group 1 (alkali metals) have ns1 as outermost electronic configuration. They are all reactive metals with low ionization enthalpies. They lose the outermost electron readily to form 1+ ion. The compounds of the alkali, with the exception of those of lithium are predominantly ionic.

Q4. Ionization enthalpy increases across a period because
Answer : Option C
Explaination / Solution:

Consider moving from lithium to fluorine across the second period, where successive electrons are added to orbitals in the same principal quantum level. The shielding of the nuclear charge by the inner core of electrons does not increase very much to compensate for the increased attraction of the electron to the nucleus. Thus, across a period, increasing nuclear charge outweighs the shielding. Consequently, the outermost electrons are held more and more tightly and the ionization enthalpy increases across a period.

Q5. In the periodic table Electronegativity generally
Answer : Option D
Explaination / Solution:

The electronegativity value increases as the effective nuclear charge on the atomic nucleus increases. In a period moving from left to right, the electronegativity increases due to decrease in atomic radii resulting an increase in effective nuclear charge. Whereas, in a group moving from top to bottom, the electronegativity decreases because atomic radius increases due to subsequent addiiton of shells.

Q6. Select the species which are iso-electronic (same number of electron) with each other.
Answer : Option A
Explaination / Solution:

Neutral Cl ( Z=17) has 17 electrons and with the addition of one more electron it becomes Cl- anion which has 18 electrons.

Neutral Ca (Z=20) has 20 electron and with the removal of 2 electrons it becomes Ca2+ cation which has 18 electrons.

Since Cl and Ca2+ both has 18 electrons , so they are isoelectronic. 


Q7. Generally, the first ionization energy increases along a period including some exceptions. One which is NOT an exception is ______.
Answer : Option B
Explaination / Solution:

The high ionization energy of B, N and Mg is due to the presence of stable electronic configuration in these atoms as compared to the next element in the period. For ex. Be (Is2 2s2) has competely filled orbitals as compared to B (1s2 2s2 2p1) where there is one electron in p-orbital that can easily be lost. Therefore, B has a lower ionization energy than Be.

Q8. The outer electronic configuration of a p- block element is:
Answer : Option C
Explaination / Solution:

In the p-block elements, the last electron enters in p-orbital of valence shell and electronic configuration of valence shell is ns2 np1-6.

Q9. To which block of elements in the periodic table  belongs?
Answer : Option D
Explaination / Solution:

d-block element have the general outermost electronic configuration as (n-1)d1-10 ns0-2.

Q10. General electronic configuration of s-block elements is:
Answer : Option C
Explaination / Solution:

The elements of Group 1 (alkali metals) and Group 2 (alkaline earth metals) which have ns1 and ns2 outermost electronic configuration belong to the s-Block Elements. The general electronic configuration of the valence shell for s-block elements is ns1-2.