Let's start from the Fluorine (F), which has 4 atoms on the right side: this means we must put a factor 4 in front of HF to balance the number of atoms of Fluorine.
Nowe we have 4 atoms of hydrogen, H, on the left side. Since we have a

on the right side (2 atoms), we must put a factor 2 in front of

, to balance the number of atoms of hydrogen.
So now the atoms of oxygen are also balanced (2 on both sides), as well as the atoms of Silicon (Si), so the balanced reaction is
Let the beam is of length L
Now the stress on both the end is same
now we can say that torque on the beam due to two forces must be zero

also we know that stress at both ends are same


Now from two equations we have

solving above equation we have

<em>so the load is placed at distance 0.4L from the end of 12 mm^2 area</em>
A. The Sun is the only star in the Solar System. This is the only star we know of.
I hope this helps!!
Answer is d using a heavier string