Question

The lattice site in a pure crystal can not be occupied by _________________
A.Molecule
B.Ion
C.Electron
D.Atom

Answer 1

Hint: Each point in a lattice is known as lattice point which are either atom or molecule or ion which are joined together by a straight line to bring out geometry of lattice in pure crystal constituents are arranged in fixed stoichiometric ratio. Lattice is defined as the arrangement of atoms or groups of atoms in a crystal. It contains a high level of symmetry. There are many types of lattice structure like cubic , hexagonal and many more.

Complete step by step answer:
MOLECULE:- Crystal lattice is made up of a combination of atoms also .
Hence molecules can be present in them . So this option is not correct.
B.ION :- When some defects occur in a lattice the compound gets broken down and dissociates and exists as an ion in the crystal lattice . It can occur in the case of interstitial defect. Hence this option is not correct.
C.ELECTRON :- They can not themselves occupy the lattice site but they can occupy the vacant sites left by an atom when defect occurs in crystal lattice as in the case of $SrCl_2$. Hence this option is correct
D.ATOM:- Atoms are the main constituent of lattice sites . They occupy lattice sites and sometimes combine to form molecules. Hence this option is not correct.
 Our required answer is c that is electron.

Note:
There are 14types of Bravais lattice that are used. They are included under orthorhombic , monoclinic , rhombic , cubic , tetragonal and many more. They are body centred (that contains site on centre of body) end centred ( that contains lattice point on each edge)