Question

Which metal among the following has the highest packing efficiency?
A.Iron
B.Aluminium
C.Tungsten
D.Polonium

Answer 1

Hint: The arrangement of particles that make up a crystal is defined by a lattice, which is an ordered sequence of points. The lattice points define the unit cell of a crystal. The unit cell is the smallest element of a crystal that, when translated in three dimensions on a regular basis, forms the entire crystal.

Complete answer: Each corner of the cube-shaped unit cell has just one lattice point in the basic cubic structure. They indicate the location of a single atom or a group of atoms called a motif, which is replicated throughout the lattice. Polonium (Po) crystallises in a plain cubic form, according to reports. Simple cubic structure has a packing efficiency of 52.4 percent.
A body-centered cubic (BCC) solid is what this is called. The atoms in the corners of a BCC unit cell do not make contact with one another, but they do make contact with the atom in the centre. A BCC unit cell has two atoms: one-eighth of an atom in each of the eight corners and one atom in the centre. Iron and tungsten are two examples of BCC. BCC has a packaging efficiency of 68 percent.
Atoms are found at the corners and, as the name suggests, at the centres of the faces of a face-centered cubic solid's unit cells. In an FCC structure, atoms are squeezed as tightly together as possible, with atoms taking up 74% of the space. Cubic nearest packing is another name for this arrangement (CCP). Aluminum is the best example.
Hence option B is correct.

Note:
The unit cell in a cubic close-packed (ccp) arrangement of atoms is made up of four layers. The top and bottom layers (a) each have six atoms at the hexagon's corners and one atom in the middle. The atoms in the second layer (b) fit into the first layer's depressions.