Explain why CO2-3 ion cannot be represented by a single Lewis structure. How can it be best represented?
A single Lewis structure of CO2-3 ion cannot explain all the properties of this ion. It can be represented as a resonance hybrid of the following structures:
If it were represented only by one structure, there should be two types of bonds, i.e., C = O double bond and C – O single bonds but actually all bonds are found to be identical with same bond length and same bond strength.
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?
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.
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 |
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?
Write Lewis structure of the following compounds and show formal charge on each atom. HN03, No2, H2so4
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.
Name the two conditions which must be satisfied for hydrogen bonding to take place in a molecule.
What is an ionic bond? With two suitable examples explain the difference between an ionic and covalent bond?
Arrange the following bonds ‘in order of increasing ionic character giving reason.
N-H, F-H, C-H and O-H
Arrange the bonds in order of increasing ionic character in the molecules: LiF, K2O, N2, SO2 and ClF3.
Is there any change in the hybridisation ofB and N atoms as a result of the following reaction ? BF3 + NH3 ——-> F3 B.NH3
Considering X-axis as the intemuclear axis which out of the following will not form a sigma bond and why? (a) Is and Is (b) Is and 2px (c) 2py and 2py (d) Is and 2s
(a) Define dipole moment. What are the units of dipole moment?
(b) Dipole moment values help in predicting the shapes of covalent molecules. Explain.
(a) How many a and n bonds are present in
(b) Why Hf is more stable than H2?
(c) Why is B2 molecule paramagnetic?
Which of the following statements are correct about CO32- ?
(a) The hybridization of central atom is sp3.
(b) Its resonance structure has one C – O single bond and two C = O double bonds.
(c) The average formal charge on each oxygen atom is 0.67 units.
(d) All C – O bond lengths are equal.
Structures of molecules of two compounds are given below:
(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?
Assertion (A): Among the two O – H bonds in H20 molecule, the energy required to break the first O – H bond and other O – H bond is the same.
Reason (R): This is because the electronic environment around oxygen is the same even after breakage of one O – H bond.
(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.
Write Lewis symbols for the following atoms and ions: S and S2– ; Al and Al3+; H and H–
Apart from tetrahedral geometry, another possible geometry for CH4 is square planar with the four H atoms at the comers of the square and the C atom at its centre. Explain why CH4 is not square planar?
Out of bonding and antibonding molecular orbitals, which one has lower energy and which one has higher stability?
In which of the following molecule/ion all the bonds are not equal?
(a) XeF4
(b) BF–4
(c) C2H4
(d) SiF4
Using molecular orbital theory, compare the bond energy and magnetic character of 0+2 and O–2
Explain why CO2-3 ion cannot be represented by a single Lewis structure. How can it be best represented?
Match the shape of molecules in Column I with the type of hybridization in Column II.
| Column I | Column II |
| (i) Tetrahedral | (a) sp2 |
| (ii) Trigonal | (b) sp |
| (iii) Linear | (c) sp3 |
Use Lewis symbols to show electron transfer between the following atoms to form cations and anions (a) K and S (b) Ca and O (c) Al and N.
Although both CO2 and H2O are triatomic molecules, the shape of H2O molecule is bent while that of CO2 is linear. Explain this on the basis of dipole moment.
The skeletal structure of CH3COOH as shown below is correct, but some of the bonds are shown incorrectly. Write the correct Lewis structure for acetic acid.
What is the total number of sigma and pi bonds in the following molecules?
(a) C2 H2 (b) C2 H4
Write the important conditions required for the linear combination of atomic orbitals to form molecular orbitals.
Compare the relative stability of the following species and indicate their magnetic properties: O2, O2, O2– (Superoxide),O22- (peroxide)
