Tiêu đề 04. CHEMICAL BONDING AND MOLECULAR STRUCTURE.pdf ✅

(1.) Which of the following statements regarding chemical bond is incorrect ? [Page: 97] (a) The attractive force that holds various constituents together in different species is called a chemical bond. (b) Lewis postulated that atoms achieve the stable octet when they are linked by chemical bonds. (c) The bond formed as a result of the electrostatic attraction between two positively ions is termed as the electrovalent bond. (d) When two atoms share one electron pair they are said to be joined by a single covalent bond. (2.) What is the electrovalency and charge of calcium and chlorine respectively ? [Page: 97] (a) Positive electrovalence of two and negative electrovalence of one. (b) Negative electrovalence of one and positive electrovalence of two. (c) Positive electrovalence of one and negative electrovalence of two. (d) Negative electrovalence of two and positive electrovalence of one. (3.) Select the correct statement regarding octet rule. [Page: 98] (a) Atoms can combine by transfer of valence electrons from one atom to another, gaining or losing. (b) Atom can combine by sharing of valence electrons in order to have an octet in their valence shells. (c) Both a and b are correct. (d) Neither a nor b are correct. (4.) Which of the following species does not possess triple bond? [Page: 99] (a) C H2 2 (b) N2 (c) CCl4 (d) HCN (5.) Which of the following representation is incorrect with respect to electron dot structure ? [page: 99] (a) (b) (c)
(d) (6.) In CH 4 molecule, how many valence electrons are available for bonding) [Page: 99] (a) Eight (b) Four (c) Six (d) Ten (7.) Select the correct statement. [Page: 99] (a) In 2 3 3 NF and CO , nitrogen and fluorine are the central atoms whereas carbon and oxygen occupy the terminal positions. (b) In 2 3 3 NF and CO , nitrogen and carbon are the central atoms whereas fluorine and oxygen occupy the terminal positions. (c) In 2 3 3 NP and CO , fluorine and oxygen are the central atoms whereas nitrogen and carbon occupy the terminal positions. (d) In 2 3 3 NF and CO , nitrogen and oxygen are the central atoms whereas fluorine and carbon occupy the terminal positions. (8.) Central oxygen atom in ozone ( ) O3 consists of formal charge equal to [Page: 100] (a) −1 (b) 0 (c) +1 (d) None of these (9.) How many lone pairs of electrons are available in ozone molecule ? [Page: 10l] (a) Eight (b) Four (c) Two (d) Six (10.) Some statements regarding formal charge are given below. Identify the correct statement(s). [Page: 100] (I) Formal charges do not indicate real charge separation within the molecule. (II) Formal charges help in the selection of the lowest energy structure from a number of possible Lewis structures for a given species. (III) In polyatomic ions, it is feasible to assign a formal charge on each atom. (a) I only (b) II and III (c) I and III (d) I, II and III (11.) Which of the following is an example of odd electron molecule? [Page: 10l] (a) BCl3 (b) NO (c) CO (d) H O2
(12.) Identify the molecule which has incomplete octet of the central atom. [Page: 10l] (a) BeH2 (b) C H2 2 (c) NP3 (d) CO2 (13.) Which of the following pairs of molecules has expanded octet) [Page: 10l] (a) 6 2 SP , H O (b) H SO , Li Cl 2 4 (c) 5 6 PF and SF (d) CO and PF 2 5 (14.) Match Column I with Column II and select the correct code given below: [Page: 10l] ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) 3 2 4 2 3 Column I Column II Molecule Octet rule P BCl 1 Expanded octet Q H SO 2 Odd electron R NO 3 Incomplete octet S NP 4 Complete octet (a) P‐ 1, Q‐2, R‐3, S‐4 (b) P‐4, Q‐3, R‐2, S‐ 1 (c) P‐3, Q‐ 1, R‐4, S‐2 (d) P‐3, Q‐ 1, R‐2, S‐4 (15.) Which of the following molecules follows the octet rule ? [Page: 10l] (a) 2 SCl (b) 6 SF (c) NO2 (d) LiCl (16.) Some statements regarding octet theory are given below. Identify the correct statement(s).[Page: 99] (I) This theory does not account for the shape of molecules. (II) It does not explain the relative stability of the molecules. (III) This theory is totally silent about the energy of a molecule. (a) II only (b) I and III (c) II and III (d) I, II and III (17.) Two general equations are given below. [Page: 102] (i) M g M g e ( ) ( ) + → + (ii) X g e X g ( ) ( ) − + → Equations (i) and (ii) are termed respectively as (a) ionisation enthalpy and electron gain enthalpy.
(b) electron gain enthalpy and ionisation enthalpy. (c) electron gain enthalpy and electron gain enthalpy. (d) ionisation enthalpy and ionisation enthalpy. (18.) Which of the following statements is correct [Page: l02] (a) The ionisation process may be exothermic or endothermic. (b) The electron gain process may be exothermic or endothermic. (c) The ionisation is always exothermic process. (d) The electron gain process is always exothermic process. (19.) Ionic bonds will be formed more easily [Page: 102] (a) between elements with comparatively low ionisation enthalpies and elements with comparatively high negative value of electron gain enthalpy. (b) between elements with comparatively high ionisation enthalpies and elements with comparatively low negative value of electron gain enthalpy. (c) between two elements which consist of low ionisation enthalpy and electron gain enthalpy. (d) between two elements which consist of high ionisation enthalpy and electron gain enthalpy. (20.) For general ionic compounds, choose the correct characteristics. [Page: 102] (a) Cations derived from metallic elements and anions from non‐metallic elements. (b) Anions derived from metallic elements and cations from non‐metallic elements. (c) Both cations and anions derived from nonmetallic elements. (d) Both cations and anions derived from metallic elements. (21.) Rock salt is termed as [Page: 102] (a) M C 2 g l (b) CaCl 2 (c) NaCl (d) BeI 2 (22.) In ionic solids, the sum of the electron gain enthalpy and the ionisation enthalpy may be positive but still the crystal structure gets stabilised [Page: 102] (a) due to the energy released in the formation of the crystal lattice. (b) due to the energy absorbed in the formation of the crystal lattice. (c) due to bigger size of cations. (d) due to smaller size of anions. (23.) The lattice enthalpy of an ionic solid is defined as the energy required to completely separate [Page: 103] (a) one mole of a solid ionic compound into liquid constituent ions. (b) one mole of a gaseous ionic compound into solid constituent ions. (c) one mole of a solid ionic compound into gaseous constituent ions.