Chapter 1 the Solid State Class 12 Chemistry NCERT Solutions

Question 1.1: Why are solids rigid?

Question 1.2: Why do solids have a definite volume?

Question 1.3: Classify the following as amorphous or crystalline solids: Polyurethane, naphthalene, benzoic acid, teflon, potassium nitrate, cellophane, olyvinylchloride, fibre glass, copper.

Question 1.4: Why is glass considered a super cooled liquid?

Question 1.5: Refractive index of a solid is observed to have the same value along all directions. Comment on the nature of this solid. Would it show cleavage property?

Question 1.6: Classify the following solids in different categories based on the nature of intermolecular forces operating in them:
Potassium sulphate, tin, benzene, urea, ammonia, water, zinc sulphide, graphite, rubidium, argon, silicon carbide.

Question 1.7: Solid A is a very hard electrical insulator in solid as well as in molten state and melts at extremely high temperature. What type of solid is it?

Question 1.8: Ionic solids conduct electricity in molten state but not in solid state. Explain.

Question 1.9: What type of solids are electrical conductors, malleable and ductile?

Question 1.10: Give the significance of a ‘lattice point’.

Question 1.11: Name the parameters that characterize a unit cell.

Question 1.12: Distinguish between (i) Hexagonal and monoclinic unit cells (ii) Face−centred and end−centred unit cells.

Question 1.13: Explain how much portion of an atom located at (i) corner and (ii) body−centre of a cubic unit cell is part of its neighboring unit cell.

Question 1.14: What is the two dimensional coordination number of a molecule in square close packed layer?

Question 1.15: A compound forms hexagonal close−packed structure. What is the total number of voids in 0.5 mol of it? How many of these are tetrahedral voids?

Question 1.16: A compound is formed by two elements M and N. The element N forms ccp and atoms of M occupy 1/3rd of tetrahedral voids. What is the formula of the compound?

Question 1.17: Which of the following lattices has the highest packing efficiency (i) simple cubic (ii) body−centred cubic and (iii) hexagonal close−packed lattice?

Question 1.18: An element with molar mass 2.7 × 10−2 kg mol−1 forms a cubic unit cell with edge length 405 pm. If its density is 2.7 × 103 kg m−3, what is the nature of the cubic unit cell?

Question 1.19: What type of defect can arise when a solid is heated? Which physical property is effected by it and in what way?

Question 1.20: What type of stoichiometric defect is shown by: (i) ZnS (ii) AgBr

Question 1.21: Explain how vacancies are introduced in an ionic solid when a cation of higher valence is added as an impurity in it.

Question 1.22: Ionic solids, which have anionic vacancies due to metal excess defect, develop colour.Explain with the help of a suitable example.

Question 1.23: A group 14 element is to be converted into n−type semiconductor by doping it with a suitable impurity. To which group should this impurity belong?

Question 1.24:What type of substances would make better permanent magnets, ferromagnetic or ferrimagnetic. Justify your Solution:.