Free NCERT Solutions For Class 12 Chemistry Chapter 1: The Solid States Free PDF Download

Question 1:
Define the term ‘amorphous’ give a few examples of amorphous solids.

Question 2:
What makes a glass different from a solid such as quartz? Under what conditions could quartz be converted into glass?

Question 3:
Classify each of the following solids as ionic, metallic, molecular, network (covalent) or amorphous.
(i) Tetra phosphorus decoxide (P4010)
(ii) Ammonium phosphate (NH4) 3PO4
(iii) SiC
(iv)I2
(v) P4
(vi) Plastic
(vii) Graphite
(viii) Brass
(ix) Rb
(x) LiBr
(xi) Si

Question 5:
How can you determine the atomic mass of an unknown metal if you know its density and the
dimension of its unit cell? Explain

Question 6:
‘Stability of crystal is reflected in the magnitude of its melting point’. Comment. Collect melting points of solid water, ethyl alcohol, diethyl ether and methane from a data book. What can you say about the intermolecular forces between these molecules?

Question 7:
How you distinguish between the following pairs of terms:
(i) Hexagonal close-packing and cubic close-packing?
(ii) Crystal lattice and unit cell?
(iii) Tetrahedral void and octahedral void?

Question 8:
How many lattice points are there in one unit cell of each of the following lattice?
(i) Face-centred cubic
(ii) Face-centred tetragonal
(iii) Body-centred

Question 9:
Explain
(i) The basis of similarities and differences between metallic and ionic crystals.
(ii) Ionic solids are hard and brittle.

Question 10:
Calculate the efficiency of packing in case of metal crystal for
(i) simple cubic
(ii) body-centred cubic
(iii) face-centred cubic (with the assumptions that atoms are touching each other).

Question 12:
A cubic solid is made of two elements P and Q. Atoms of Q are at the corners of the cube and P at the body-centre. What is the formula of the compound? What are the coordination numbers of P and Q?

Question 14:
If the radius of the octahedral void is r and radius of the atoms in close packing is R, derive
relation between r and R.

Question 17:
What is a semiconductor? Describe the two main types of semiconductors and contrast their
conduction mechanism.

Question 19:
Ferric oxide crystallises in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive the formula of the ferric oxide.

Question 20:
Classify each of the following as being either a p-type or an n-type semiconductor.
(i) Ge doped with In
(ii) B doped with Si

Question 22:
In terms of band theory, what is the difference:
(i) Between a conductor and an insulator
(ii) Between a conductor and a semiconductor

Question 23:
Explain the following terms with suitable examples:
(i) Schottky defect
(ii) Frenkel defect
(iii) Interstitials and
(iv) F-centres

Question 24:
Aluminium crystallises in a cubic close-packed structure. Its metallic radius is 125 pm.
(i) What is the length of the side of the unit cell?

Question 26:
Explain the following with suitable examples:
(i) Ferromagnetism
(ii) Paramagnetism
(iii) Ferrimagnetism
(iv) Antiferromagnetism
(v) 12-16 and 13-15 group compounds.

Intext questions

Question 1:
Why are solids rigid?

Question 2:
Why do solids have a definite volume?

Question 3:
Classify the following as amorphous or crystalline solids:
Polyurethane, naphthalene, benzoic acid, teflon, potassium nitrate, cellophane, polyvinyl chloride, fibre glass, copper.

Question 4:
Why is glass considered a super cooled liquid?

Question 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 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 7:
Solid A is 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 10:
Give the significance of a lattice point

Question 11:
Name the parameters that characterize a unit cell.

Question 12:
Distinguish between
(i) Hexagonal and monoclinic unit cells
(ii) Face-centred and end-centred unit cells.

Question 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 neighbouring unit cell.

Question 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 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 17:
Which of the following lattices has the highest packing efficiency (i) simple cubic (ii) bodycentred cubic and (iii) hexagonal close-packed lattice?

Question 19:
What type of defect can arise when a solid is heated? Which physical property is affected by it and in what way?

Question 20:
What type of stoichiometric defect is shown by:
(i) ZnS (ii) AgBr

Question 21:
Explain how vacancies are introduced in an ionic solid when a cation of higher valence is added as an impurity in it.

Question 22:
Ionic solids, which have anionic vacancies due to metal excess defect, develop colour. Explain with the help of a suitable example.

Question 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 24:
What type of substances would make better permanent magnets, ferromagnetic or ferrimagnetic. Justify your Solution.