If a body is in equilibrium under a set of non-collinear forces,then the minimum number of forces has to be

The following forces start acting on a particle at rest at the origin of the coordinate system simultaneously: ${\vec F_1} = -4\hat i - 5\hat j + 5\hat k$,${\vec F_2} = 5\hat i + 8\hat j + 6\hat k$,${\vec F_3} = -3\hat i + 4\hat j - 7\hat k$,and ${\vec F_4} = 2\hat i - 3\hat j - 2\hat k$. The particle will move:

Which of the following sets of three forces acting on a body cannot have a resultant of zero?

When is a body said to be in mechanical equilibrium?

What is the minimum number of forces acting in the same plane on a particle that can result in a zero net force?

$A$ body of weight $2 \, kg-wt$ is suspended as shown in the figure. The tension $T_1$ in the horizontal string (in $kg-wt$) is