Can a stationary object remain stationary if multiple external forces act upon it?

Consider the following statements about the blocks shown in the diagram that are being pushed by a constant force $F$ on a frictionless table:
$A.$ All blocks move with the same acceleration.
$B.$ The net force on each block is the same.
Which of these statements is/are correct?

$A$ uniform sphere of weight $W$ and radius $5\, cm$ is held by a string of length $8\, cm$ attached to a smooth vertical wall as shown in the figure. The tension in the string is:

Two persons are holding a rope of negligible weight tightly at its ends so that it is horizontal. $A$ $15\, kg$ weight is attached to the rope at the mid-point,which now no longer remains horizontal. The minimum tension required to completely straighten the rope is

If the tension in the horizontal wire shown in the figure is $30 \text{ N}$,then the weight $W$ and tension in the wire $OA$ are respectively:

For a particle to be in equilibrium,what must be the net force acting on it?