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TYPES OF CHEMICAL BONDS
IIT JEE - NEET

1) The types of bonds present in CuSO₄.5H₂O are only:

(IIT JEE 1983)

1) electrovalent and covalent 

2) electrovalent and coordinate covalent  

3) electrovalent, covalent  and coordinate covalent

4) covalent  and coordinate covalent

Logic & Solution:

* Structure of CuSO₄.5H₂O in the solid state is shown below. The Cu²⁺ ions are attracted towards SO₄^2- ions not only by ionic interactions (electrovalent) but also by coordinate covalent bonds. The Cu²⁺ ions form coordinate covalent bonds with water as well as sulfate ions.

There are covalent bonds in water and sulfate ions.

Conclusion:

The correct option is 3.

Note:

There is also hydrogen bonding between water and sulfate ions. Only four water molecules are forming dative bonds with Cu²⁺. The fifth molecules is involved in H-bonding.

Related questions

2) Which of the following contains both polar and non-polar bonds?

(IIT JEE 1997) 

1) NH₄Cl 

2) HCN

3) H₂O₂

4) CH₄

Logic & solution: 

1) In NH₄Cl, the N-H bond is polar due to appreciable electronegativity difference between N (3.0) and H (2.1).

2) In HCN, the H-C and C-N bonds are polar due to electronegativity difference between C (2.5) and N (3.0) for H-C bond as well as between C (2.5) and  H (2.1) for C-N bond.

3) In H₂O₂, the O-H bond is polar due to electronegativity difference between O (3.5) and H (2.1). Whereas, O-O bond is non-polar.

4) In CH₄, the C-H bonds are also polar.

Note: Even though, the C-H bonds have a little polarity, you might have seen that they are considered to be non-polar in the study of organic chemistry. It is a relative thing. They are less polar when compared to bonds formed by carbon with other atoms like: C-O, C-N, C-X etc. Hence C-H bonds are treated as non-polar.

But according to the tone of this question, C-H bonds are taken as polar since there is electronegativity difference. 

Conclusion:

Option '3' is correct.

3) The number and type of bonds between two carbon atoms in CaC₂ are:

(IIT JEE 1996) 

1) one σ and one π bonds 

2) one σ and two π bonds

3) one σ and one and half  π bonds

4) one σ bond

Logic & solution: 

CaC₂ can be divided into Ca²⁺ and C₂^2- ions. The structure of C₂^2- ion is shown below:

There is a triple bond between two carbons. Among three bonds, only one is sigma bond and the remaining two are pi bonds.

Conclusion:

Option '2' is correct.

4) Which one of the following molecule contains both ionic and covalent bonds?

(EAMCET 2002-E) 

1) CH₂Cl₂ 

2) K₂SO₄ 

3) BeCl₂ 

4) SO₂

Logic & solution: 

 Only in K₂SO₄, there are ionic as well as covalent bonds. The K⁺ and SO₄^2- ions are attracted by electrostatic forces. Sulfur atom has covalent bonds in sulfate ion. 

Conclusion:

Option '2' is correct.

5) Element 'X' is strongly electropositive and element 'Y' is strongly electronegative. Both are univalent. The compound formed will be:

(IIT JEE 1980) 

1) X⁺Y^-

2) Y⁺X^-

3) X-Y

4) X→Y 

Logic & solution: 

 Strongly electropositive elements tend to lose electrons due to relatively low ionization potentials to form cations (like X⁺) and strongly electronegative elements tend to gain electrons to form anions (like Y^-). Hence the bond formed between them is predominantly ionic in nature.

Conclusion:

Option '1' is correct.

6) The bond between two identical non metal atoms has a pair of electrons. The correct statement about this pair is:

(IIT JEE 1986) 

1) Unequally shared between the two.

2) Transferred fully from one atom to another

3) Has identical spins.

4) Equally shared between the atoms. 

Logic & solution: 

 Identical atoms possess same electronegativity values and hence share the electron pair equally by forming a non polar covalent bond.

Conclusion:

Option '4' is correct.

7) The bonds present in N₂O₅ are:

(IIT JEE 1986) 

1) only ionic

2) covalent and coordinate

3) only covalent

4) covalent and ionic 

Logic & solution: 

Since nitrogen and oxygen are non metals, the bonds between them are NOT ionic.

The structure of N₂O₅ is given below. There are both covalent and coordinate covalent bonds.

Conclusion:

Option '2' is correct.

Homework

1) ?