Question

Assertion : Total number of atoms in body centred unit cell is 2.

Reason : In body centred unit cell, an atom is at each of its corners and one atom at its

body centre.​

Answer 1

Answer:

Assertion:

Total number of atoms in body centred unit cell is 2.

True

Reason:

In body centred unit cell, an atom is at each of its corners and one atom at its body centre.

True

Hence, Both Assertion and Reason is true and Reason is the correct explanation for the assertion.

Let us see how :

• 8 atoms in all corners, so, 8 corners×1/8 per atom = 8×1/8 = 1 atom
• 1 body centred atom = 1×1 = 1 atom

Hence, the total number of atoms per unit cell = 2 atoms

Extra Information:

• The unit cells can be classified into two types : Primitive unit cell and Centred unit cell.
• In Primitive unit cell, atoms are present at the corners.
• In Centred unit cell, the atoms are present at different positions in addition to atoms at the corners. The three basic types of Centred unit cells are :

1. Body centred unit cell : Contains one atom at its body centred with the ones present at the corners.
2. Face centred unit cell : Contains one atom at each face with the ones present at the corners.
3. End centred unit cell : Contains one atom at the centre of any two opposite faces with the ones present at the corners.

Answer 2

Required Answer :-

Both reason and assertion are correct and reason is correct explanation of assertion

Explanation -

8 corners are there. So, If one corner has one atom eight corners will have 8 × 1 = 8 atom.

Each part has 1/8 atom

Atom in center = 1

Total atom = 1 + 1

Total atom = 2

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Know More :-

Atoms - Atom is the smallest part of any matter which cannot be broken into parts.