Problem 33
Regarding covalency which of the following statements is wrong? (1) In covalency, sharing of electrons takes place. (2) Maximum covalency is restricted to \(8 .\) (3) Covalency is the number of electron pairs shared by an atom. (4) Covalency of an atom is equal to the number of electrons contributed by an atom in the formation of covalent bonds.
Problem 34
The nature of bonding in \(\mathrm{CCl}_{4}\) and \(\mathrm{CaH}_{2}\) is (1) electrovalent in both \(\mathrm{CCl}_{4}\) and \(\mathrm{CaH}_{2}\) (2) covalent in \(\mathrm{CCl}_{4}\) and electrovalent in \(\mathrm{CaH}_{2}\) (3) electrovalent in \(\mathrm{CCl}_{4}\) and covalent in \(\mathrm{CaH}_{2}\) (4) covalent in both \(\mathrm{CCl}_{4}\) and \(\mathrm{CaH}_{2}\)
Problem 38
A solid substance is soft, has low melting point and is poor conductor of electricity. The substance is most likely (1) an ionic solid (2) network solid (3) a metallic solid (4) a molecular solid
Problem 40
The electronic configuration of 4 elements \(\mathrm{K}, \mathrm{L}, \mathrm{M}\) and \(\mathrm{N}\) are \(K=1 s^{2} 2 s^{2} 2 p^{1}\) \(L=1 s^{2} 2 s^{2} 2 p^{6}\) \(\mathrm{M}=1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{4}\) \(\mathrm{N}=1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{3}\) The element that would form a diatomic molecule with double bond is (1) \(\mathrm{K}\) \(\begin{array}{lll}\text { (2) L } & \text { (3) } \mathrm{M} & \text { (4) } \mathrm{N}\end{array}\)
Problem 41
The central atom in a molecule has three bond pairs and one lone pair of electrons. The shape of the molecule is (1) Triangular (2) Pyramidal (3) Linear (4) Tetrahedral
Problem 43
Two lone pairs of electrons and two bond pairs are present in (1) \(\mathrm{NH}_{3}\) (2) BF \(_{3}\) (3) \(\mathrm{CO}_{3}^{2}\) (4) \(\mathrm{H}_{2} \mathrm{O}\)
Problem 44
\(\mathrm{BCl}_{3}\) is a planar molecule, whercas \(\mathrm{NCl}_{3}\) is pyramidal because (1) \(\mathrm{BCl}_{3}\) has no lonc pair of electrons but \(\mathrm{NCl}_{3}\) has a lone pair of clectrons. (2) B-Cl bond is more polar than N-Cl bond. (3) Nitrogen atom is smaller than boron atom. (4) N-Cl bond is more covalcnt than B-Cl bond.
Problem 45
More the number of lone pairs of electrons on the central atom (1) greater is the contraction in the angle between bond pairs (2) the smaller is the contraction in the angle between BPs (3) no effect on bond angle (4) all
Problem 46
The II-O-II bond angle in \(\mathrm{II}_{2} \mathrm{O}\) is \(104.5^{\circ}\) and not \(109^{\circ} 28^{\prime}\) because of (1) high electronegativity of oxygen (2) bond pair-bond pair repulsion (3) Lonc pair-lone pair repulsion (4) Lonc pair-bond pair repulsion
Problem 47
The lone pair of electrons in a molecule spread out (1) more than the bond pair electrons (2) less than the bond pair electrons (3) as much as the bond pair electrons (4) only when they are present in oxygen atoms
