Advertisements
Advertisements
Question
Which of the following features are not shown by quartz glass?
(i) This is a crystalline solid.
(ii) Refractive index is same in all the directions.
(iii) This has definite heat of fusion.
(iv) This is also called super cooled liquid.
Advertisements
Solution
(i) This is a crystalline solid.
(iii) This has definite heat of fusion.
Explanation:
Quartz glass is an amorphous solid so it has not definite heat of fusion. This is due to short range order of molecule while quartz glass is also known as super cooled liquid and isotropic in nature.
| Crystalline Silica (Quartz) | Amorphous Silica (Glass) | |
| 1. | Crystalline in nature. Also called quartz. |
Light white powder. |
| 2. | All four corners of \[\ce{SiO^{4-}4}\], tetrahedron are shared by others to give a network solid. |
The \[\ce{SiO^{4-}4}\], tetrahedron are randomly joined giving rise to polymeric chains, sheets or three - dimensional units |
| 3. | High and sharp melting point (1710°C) |
Does not have sharp melting point. On heating softens gradually to liquid. |
APPEARS IN
RELATED QUESTIONS
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?
Define the term ‘amorphous’.
‘Stability of a crystal is reflected in the magnitude of its melting points.’ 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?
Write any two differences between amorphous solids and crystalline solids
Why does sodium chloride on heating with sodium vapours acquire yellow colour?
Amorphous solids are also known as ____________.
Most crystals show good cleavage because their atoms, ions or molecules are ____________.
“Crystalline solids are anisotropic in nature″. What is the meaning of anisotropic in the given statement?
A crystalline solid ____________.
Which of the following is not a crystalline solid?
Which of the following is an amorphous solid?
Which of the following statement is not true about amorphous solids?
The sharp melting point of crystalline solids is due to ______.
Why some glass objects from ancient civilisations are found to become milky in appearance?
Amorphous solid can also be called:
(i) pseudo solids
(ii) true solids
(iii) supercooled liquids
(iv) supercooled solids
The property of crystalline solid is not ______.
Assertion A: Sharp glass edge becomes smooth on heating it upto its melting point.
Reason R: The viscosity of glass decreases on melting.
Choose the most appropriate answer from the options given below.
An ionic solid AB2 isomorphous to the rutile structure (a tetragonal system with the effective number of formula units = 2) has edge lengths of the unit cell of 4Å, 4Å and 7Å. The density of the substance is ______ mg/cc. (if its formula weight is 80. The NA = 6 × 1023 and express your answer in mg/cc using four significant digits.)
