Ial m1 oct 22 q

Hmm... maybe getting an actual rod and string (or equivalent setup) will help you understand.
But the idea is as the mass hanging at B gets bigger, the rod is going to "tip over" eventually. At that point tension at C is 0, as the rod isn't even in contact with the rod anymore.

EDIT: A similar setup would be for you to hold a ruler at two points in the middle, and have your friend push down on one end, say on your right. Eventually the ruler will leave your left finger, meaning no normal force acting on the ruler by your left finger. Now take this setup and flip it upside down, or bring it to Australia or something.

This does make sense. THANK U SOO MUCH? Also will this tip over thing only work with the largest mass/ weight right? Like if its smallest possible value for M, we will cnsider Tc ?

In general with mechanics, it really helps if you first take a minute just to understand how the system works. In this particular question, smallest possible value of M is not really an interesting question, since the system stays in equilibrium naturally without help of any external forces.

I believe if you move your pivot points (C, D) so that both of them are on the left(/right) to the center of mass of the rod, then we can talk about smallest possible value of M. Think about why.

okay i do get some idea about the question asked. Ig its a sneaky tilting question. Thank you for your help and advice!

Nice one.

Maybe I should point out that so far, I have done zero mathematics. All of my hints were simply a case of "sit and think before doing the boring algorithmic stuff". Which is in fact the key to doing maths!

P.S. I actually have no idea how to do the question itself.