Which of the following is not a cystalline solids?

Options

A. Polyurethane
B. Copper
C. Potassium nitrate
D. Benzoic acid

Answer

1

Explanation

Crystalline solids are those whose atoms,molecules or ions have an ordered arrangement extending over a long range ,This order on the atomic level is also seen on the visible level because crystalline solids usually have flat faces and distant angles.
Glass ,rubber polymers and plastics are typical examples of amorphous solids .Polyurethane being a polymer is a non=crystalline solids.
Crystals range in size from those large enough for their faces or cleavage planes to be evident at a glance to those so small that they seem to be powerful as an electron microscope or `X` ray diffraction techiniques,may be used ot detect their crystalline structure.
The way in which a crystal grows affects its size .Size is inversely proportional to the rate of growth.i.e, if a crystal grows slowly from the liquids state or form solutionsthere is greater opportunity for large crystals to form,Crystals exist in a variety of shapes.The way in which a crystal of a given substance is formed may affect its shape .For example a cystal of `NaCl` grown by subspension in the centrer of a solution of `NaCl` will have a symmterical cubic shape because `NaCl` deposits at an equal rate on all sides of the crystal.i.e, all faces of the crystal grown equally.But if the crystal is grown on the button of the container ,then the crystal growns faster horizonatlly then vertically because material is not deposited on the face that touches the bottom. The shape of a crystal of `NaCl` can be changed even further by ther variations in the conditions of growth.