If torque is calculated relative to a reference point and this point is displaced,does the condition for rotation remain valid?

In a physical balance working on the principle of moments,when $5\, mg$ weight is placed on the left pan,the beam becomes horizontal. Both the empty pans of the balance are of equal mass. Which of the following statements is correct?

$A$ metre stick is balanced on a knife edge at its centre. When two coins,each of mass $5\; g$ are put one on top of the other at the $12.0 \;cm$ mark,the stick is found to be balanced at $45.0\; cm$. What is the mass of the metre stick?

$A$ weightless rod is acted on by upward parallel forces of $2N$ and $4N$ at ends $A$ and $B$ respectively. The total length of the rod $AB = 3m$. To keep the rod in equilibrium,a force of $6N$ should act in the following manner:

Shown in the figure is a rigid and uniform one-meter-long rod $AB$ held in a horizontal position by two strings tied to its ends and attached to the ceiling. The rod has a mass $m$ and another weight of mass $2m$ is hung at a distance of $75\, cm$ from $A$. The tension in the string at $A$ is $....mg$.

$A$ rod of mass $M = 1 \ kg$ and length $L = 1 \ m$ is suspended horizontally by two ideal strings as shown in the figure. The strings are attached at a distance of $1/3 \ m$ from each end. First, a mass $m_1$ is suspended from the left end while keeping the rod horizontal. Then, a second mass $m_2$ is suspended from the right end, again keeping the rod horizontal. What is the maximum total mass $(m_1 + m_2)$ that can be suspended in this way while maintaining the horizontal orientation of the rod?