Question

29. Use VSEPR theory to predict the molecular geometry (shape) of nitrogen trichloride, NCI A. linear B. trigonal planar C. bent D. tetrahedron E trigonal pyramidal 30. The hybridization of the central atom in SO2 is_ A sp B. sp C. sp D. sp'd E. sp ? 31. Which has the highest melting point? A. NaCl В. Сао C, KF D. Fe2O3 E. LiBr but differing 32. Isotopes are atoms that have the same A. atomic masses, charges B. mass numbers, atomic numbers C. atomic numbers, mass numbers D. charges, atomic masses E mass numbers, charges

Answer 1

Question-29 . According to Valance Shell Electron Pair Repulsion Theory , NCl3 has One lone pair and Three bond pairs as Nitrogen has atomic number 7 , so valance shell electrons are 5 , 3 valance electrons forms single covalent bonds with Three Cl atoms and One electron pair is remians unshared which is lone pair . Due to one lone pair shape is distored from Regular tetrahedral geometry .

Shape will be Trigonal Pyramidal . Answer is option E.

Question-30 Central atom is SO2 is S , Sulphur with atomic number 16 has valance shell electronic configuration as 3s2 3p4

while in excited state : 3s2 3p3 3d1

so one s-orbital and three p - orbitals intermix to give sp2 hybridisation .

Two of the three sp2-orbitals form two sigma bonds with two oxygen atoms while third contains the lone pair of electrons .

Question-31 . Melting point is the temperature at which solid starts melting to give liquid at atmospheric pressure .

melting point depends on strength of interparticle forces . Stronger are interparticles forces , highest will be the melting point .Here CaO is an ionic compound with strong Elctrostatic forces of attraction between Ca2+ and O2- . Due to high charge to size ration , the ionic bond formed is strong . So CaO has highest meting point equal to 2570 degree Celcius So option B is the answer .

Question-32 In the word isotope , Iso means same and topes means atomic number .

so isotopes are the atoms of same element which has same atomic number but different mass number . so example carbon has three isotops with atomic number same as =6 , but different mass number as 12.13,14.

so option C is right answer .

For more information and detailed solution , please refer to images as attached.
Page- The Woad Iso means same or and topes means atomic Numbes So Isotopes are the atoms of Same element which has same atomic Numbes but different mars Number. So they have same atomit Number, same Valence Mertent. and same charge in compounds for example: Hydrogen has three Isotopes Deuterin 1 H Tritium 0 34 All these Three Have ame atomic Number = 1, But different mars Number as 1,231 So Answer is obtion o atomic number, mass

E Page - Question - 29 :- Answer: - Trigonal Pyramidal. According to Valance shell Electronpaper repulsion d (VSEPR) theory, Nelz Has Three bond pairs and One lone pair. NU Hybridisation » Sp3 Nelz Has Lone Pairy = 1 , Bond Pairs=3 u Lone Pair Geometry on shape i Bond Pair Trigonal e Pyramidal. Due to presence of one is distorted and it is lone Pair geometry trigonal pramidal

Question (30) Page Hybridisation of Central atom in Sog is spa Sulphur (s) = atomic number=16 Electronic con fig Wiations indag*ap'as Valance shell Electronic configuration up to 382 364 Cound 14 141111 HUI state 38 39 sin excited State 1L 111 1 35 36 3ds fb? 3d In Sog is is s62 Hybridized Two of three spa Hybridised forme two sigma bonds with oxygen mith ovu gen atomy.

Page-69 melting point: - the temperature o at which liquid substance is start forming from solid substance at atmospheric Pressure. * meeting point depends on Strength of Inter particle forces. * Greater is magnitude of guter Particle forcy more will be melting point * Nall = do nic bonds between Nut and lo => melting point of Nall = 8010 * (GO => Jonic bonds between Capt and of - melting point of CaO => 2570°C * KF => Jonic bonde o melting point of K F = 8 50%. * Fag O3 3 Pelar covalent or hearly Jonic bonds. a melting Point 15 60°C. o MAY 2013

Page => W - Liber = Jonic bonds. Voto melting point => 550°C. So Cao Has maximum or Highest In the melting point among these. * CaO Has Highest melting point due to strong inter-jonic forces of attraction between Cart and 02- Both have high charge to size ratio . so strength of Tonic forces is high and hence High melting point So Answer option B Cao