Chemistry

Chemical Bonding and Molecular Structure

Question:

Match the species in Column I with the geometry/shape in Column II.

Column I Column II
(i) H30+ (a) Linear
(ii) HC = CH (b) Angular
(iii) Cl02 (c) Tetrahedral
(iv) NH+4 (d) Trigonal bipyramidal
(e) Pyramidal

Answer:

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Chemical Bonding and Molecular Structure

Q 1.

Elements X, Y and Z have 4, 5 and 7 valence electrons respectively, (i) Write the molecular formula of the compounds formed by these elements individually with hydrogen, (ii) Which of these compounds will have the highest dipole moment?

Q 2.

Briefly describe the valence bond theory of covalent bond formation by taking an example of hydrogen. How can you interpret energy changes taking place in the formation of dihydrogen?

Q 3.

What is the effect of the following processes on the bond order in N-, and 02?
(i) N2 → N+2 + e (ii) 02 → O+2 + e

Q 4.

Which of the following statements are not correct?
(a) NaCl being an ionic compound is a good conductor of electricity in the solid state.
(b) In canonical structures there is a difference in the arrangement of atoms.
(c) Hybrid orbitals form stronger bonds than pure orbitals.
(d) VSEPR theory can explain the square planar geometry of XeF4.

Q 5.

Match the items given in Column I with examples given in Column II.

Column I Column II
(i) Hydrogen bond (a) C
(ii) Resonance (b) LiF
(iii) Ionic solid (c) H2
(iv) Covalent solid (d) HF
  (e) 03

Q 6.

Structures of molecules of two compounds are given below:

ncert-exemplar-problems-class-11-chemistry-chapter-4-chemical-bonding-and-molecular-structure-26

(a) Which of the two compounds will have intermolccular hydrogen bonding and which compound is expected to show intramolecular hydrogen bonding?
(b) The melting point of a compound depends on. among other things, the extent of hydrogen bonding. On this basis explain which of the above two compounds will show higher melting point.
(c) Solubility of compounds in water depends on power to form hydrogen bonds with water. Which of the above compounds will form hydrogen bond with water easily and be more soluble in it?

Q 7.

All the C – O bonds in carbonate ion (CO2-3) are equal in length. Explain.

Q 8.

Draw diagrams showing the formation of a double bond and a triple bond between carbon atoms in  C2 H4 and  C2 H2  molecules.

Q 9.

State the types of hybrid orbitals associated with (i) P in PCl5  and (ii) S in  SF6

Q 10.

Is there any change in the hybridisation ofB and N atoms as a result of the following reaction ?  BF3 + NH3 ——-> F3 B.NH3

Q 11.

Why ethyl alcohol is completely miscible with water?

Q 12.

Diamagnetic species are those which contain no unpaired electrons. Which among the following are diamagnetic?
(a) N2                                          
(b) N22-  
(c) 02                      
(d) o22-

Q 13.

Explain the shape of BrF5.

Q 14.

Define electronegativity. How does it differ from electron gain enthalpy?

Q 15.

How is bond order related to the stability of a molecule?

Q 16.

Using molecular orbital theory, compare the bond energy and magnetic character of 0+2 and O2

Q 17.

Assertion (A): Though the central atom of both NH3 and H20 molecules are sp3 hybridised, yet H – N – H bond angle is greater than that of H – O – H.
Reason (R): This is because nitrogen atom has one lone pair and oxygen atom has two lone pairs.
(a) A and R both are correct, and R is the correct explanation of A.
(b) A and R both are correct, but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A and R both are false.

Q 18.

Define the bond-length.

Q 19.

Arrange the bonds in order of increasing ionic character in the molecules: LiF, K2O, N2, SO2 and ClF3.

Q 20.

Predict the shapes of the following molecules using VSEPR theory?
(i) BeCl2(ii) SiCl4

Q 21.

How is bond order related to bond length of a molecule?

Q 22.

What are Lewis structures? Write the Lewis structure of  H2, BeF2  and  H2O.

Q 23.

Write Lewis structure of the following compounds and show formal charge on each atom.  HN03, No2, H2so4

Q 24.

3PO3  can be represented by structures 1 and 2 shown below. Can these two structures be taken as the canonical forms of the resonance hybrid representing  H3PO3? If not, give reasons for the same.
ncert-solutions-for-class-11-chemistry-chapter-4-chemical-bonding-and-molecular-structure-7

Q 25.

Write the significance of plus and minus sign in representing the orbitals,

Q 26.

What is meant by bond pairs of electrons?

Q 27.

Explain why BeH2   molecule has a zero dipole moment although the Be-H bonds are polar.

Q 28.

Which molecule/ion out of the following does not contain unpaired electrons?
(a) N+2
(b) 02                                                
(c) O22-                                        
(d) B2

Q 29.

Q 30.

What is an ionic bond? With two suitable examples explain the difference between an ionic and covalent bond?

Q 31.

Draw the Lewis structures for the following molecules and ions:
H2S, SiCl4 ,  BeF2, C032-, HCOOH

Q 32.

What is the total number of sigma and pi bonds in the following molecules?
(a) C2 H2 (b) C2 H4

Q 33.

Explain the formation of  H2 molecule on the basis of valence bond theory.

Q 34.

Use molecular orbital theory to explain why the Be2 molecule does not exist.

Q 35.

Define hydrogen bonds. Is it weaker or stronger than the van der Waals forces?

Q 36.

Write the type of hybridisation involved in  CH4,C2H4  and C2H2.

Q 37.

Out of sigma and Π  bonds, which one is stronger and why?

Q 38.

Write the Lewis dot symbols of the following elements and predict their valencies.  (i) Cl (ii) P

Q 39.

Write the state of hybridisation of boron in  BF3.

Q 40.

Arrange  O2,O2,O22-, O2+in increasing order of bond energy.

Q 41.

Which is more polar CO2  or  N2O? Give reason.

Q 42.

Define antibonding molecular orbital.

Q 43.

Name the two conditions which must be satisfied for hydrogen bonding to take place in a molecule.

Q 44.

What do you mean by Dipole moment? Draw the dipole diagram of H2O.

Q 45.

Define bond order. How is it related to the stability of a molecule?

Q 46.

(a) Define dipole moment. What are the units of dipole moment?
(b) Dipole moment values help in predicting the shapes of covalent molecules. Explain.

Q 47.

(a) How many a and n bonds are present in
ncert-solutions-for-class-11-chemistry-chapter-4-chemical-bonding-and-molecular-structure-34
(b) Why Hf is more stable than H2?
(c) Why is B2 molecule paramagnetic?

Q 48.

In N03 ion, the number of bond pairs and lone pairs of electrons on nitrogen atom are
(a) 2, 2                                       (b) 3, 1                                           (c) 1,3                                           (d) 4, 0

Q 49.

In which of the following molecule/ion all the bonds are not equal?
(a) XeF4                                  
(b) BF4                                        
(c) C2H4                                    
(d) SiF4

Q 50.

In which of the following substances will hydrogen bond be strongest?
(a) HCl
(b) H20                                          
(c) HI                                            
(d) H2S