Classification of Elements and Periodicity in Properties - Online Test

Q1. The above can be aptly described as
Answer : Option D
Explaination / Solution:

Isoelectronic species are elements or ions that have the same, or equal number of electrons. Although isoelectronic species have the same number of electrons, they are different in their physical and chemical properties.

Q2. The correct increasing order of radii of following species is ----?
Answer : Option B
Explaination / Solution:

It is because 

(i)  radius  of anion  ( anionic radius ) is greater  , and

(ii)  radius of  cation ( cationic radius ) is lesser  

than that of its parent neutral atom.


Q3. The increasing order of bond dissociation energies of following species is -----?
Answer : Option C
Explaination / Solution:

As bond order increases bond dissociation energy also increases .

Thus 

(i) the triple bonded    with bond order 

=  3

has the  highest bond dissociation energy .

(ii)   The doubly bonded   with  bond order 

= 2 

has lesser bond dissociation energy than  

(iii)   and    both  are single bonded  having the same bond order 

= 1   

but  , the  electron - electron  repulsive force  ( e  - e repulsion )  is maximum in  a  molecule   due to its small size. This accounts  for the lower bond dissociation energy of   as compared to  


Q4. The typical range of molar enthalpies for the strongest intermolecular (Hydrogen) bonds is
Answer : Option C
Explaination / Solution:

A hydrogen bond is the electrostatic attraction between two polar groups that occurs when a hydrogen (H) atom linked to a small sized highly electronegative atom such as nitrogen (N), oxygen (O), or fluorine (F). Therefore unlike a covalent bond, it has very low dissociation energy with a range of molar enthalpy = ( 4 − 25 ) kJ

Q5. In terms of period and group where would you locate the element with Z=114 in the modern periodic table?
Answer : Option C
Explaination / Solution:

Elements with atomic numbers Z = (87−114) are placed in 7th period. Thus , the element with Z=114(Flerovium) is placed in 7th period and 14th group of the modern periodic table.

Q6. An ionic compound is expected to have tetrahedral structure if  lies in the range of
Answer : Option A
Explaination / Solution:

For tetrahedral  lies in the range 0.225 to 0.414.

Q7. The relative tendency of an atom in a molecule to attract the shared pair of electrons towards itself is termed as its
Answer : Option D
Explaination / Solution:

A qualitative measure of the ability of an atom in a chemical compound to attract shared electrons to itself is called electronegativity. Unlike ionization enthalpy and electron gain enthalpy, it is not a measureable quantity. However, a number of numerical scales of electronegativity of elements viz., Pauling scale, Mulliken-Jaffe scale, Allred-Rochow scale have been developed. The electronegativity of any given element is not constant; it varies depending on the element to which it is bound.

Q8. The order of screening effect of electrons of s, p, d and f orbitals of a given shell of an atom on its outer shell electrons is:
Answer : Option B
Explaination / Solution:

Screening effect order follows s>p>d>f, this due to the nature of the orbitals involved. s-orbitals are least diffused and the two electrons in s-orbitals provide greatest shielding of the nuclear charge to the outermost electron. The diffused character increases in the order p>d>f. f-orbitals are so diffused that fourteen electrons inside them provide virtually no screening of the nuclear charge.

Q9. Which of the following is not an actinoid?
Answer : Option D
Explaination / Solution:

Terbium (Z=65) has an electronic configuration of [Xe] 4f9 6s2. It is a member of 4f-inner transition series which is called lanthanoid series. Rest option are all the members of 5f-inner transition series, also known as the actinoid series i.e. Curium ([Rn] 5f7 6d1 7s2) ; Californium ([Rn] 5f10 7s2); and Uranium ([Rn] 5f3 6d1 7s2).

Q10. A transition metal ion exists in its highest oxidation state. It is expected to behave as
Answer : Option B
Explaination / Solution:

If the metal is at its highest oxidation state, then it will have no desire to loose more electrons. It will have the tendency to gain electron, and go to a lower oxidation state, i. e. it behaves like an oxidizing agent.