(i) Define equilibrium.
(ii) In a beam balance when the beam is balanced in a horizontal position, it is in ……………equilibrium.

Hint: Equilibrium is a state of balance or a stable situation where opposing forces cancel each other out and where no further changes are occurring.

Complete step by step answer:
Explanation: Equilibrium: Equilibrium may be defined as the condition of a body when the number of forces acting on a body produces no change in its state of rest or of the motion of the body.
Condition of equilibrium:
The followings are the conditions of equilibrium-
The Sum of all the horizontal forces is zero. i.e. $\sum {H = 0} $
where $H$ is representing the horizontal force.
Sum of all the vertical forces is zero. i.e. $\sum {V = 0} $
where $V$ is representing the vertical force.
The Sum of net moments acting on the body is zero. i.e. $\sum M = 0$
where $M$ is representing the moment acting on anybody.
In a beam balance when the beam is balanced in a horizontal position, it is in static equilibrium.
This is because an object is in static equilibrium if and only if the sum of the forces on it in each direction is zero, as here the beam is the horizontal balanced position, hence it is in static equilibrium.

Note:
Always remember that there are three types of equilibrium. These are -
Static equilibrium: If an object is at rest and is in a state of equilibrium, then we would say that the object is at "static equilibrium.
Dynamic equilibrium: A body rotating or moving with uniform speed has a net force is zero. Such equilibrium conditions are known as Dynamic Equilibrium
Neutral equilibrium: Neutral equilibrium a state of equilibrium that is independent of a system's displacements from its original position stable equilibrium a system, when displaced, experiences a net force or torque in a direction opposite to the direction of the displacement unstable equilibrium