Consider the three cases given in figures shown. Assume the friction to be absent everywhere and the pulleys to be light; the string connecting the blocks to another block. or fixed vertical wall to be light and inextensible. Let $T_A,T_B\text{and}{T}_C$ be the tension in the strings in, $figureA,figureB\text{and}figureC$ respectively. Then pick the correct comparison between the given tensions (for the instant shown from options below,

The correct option is B $T_B=T_C<T_A$
Draw FBD for block in figure $\left(A\right)$.



Find the value of tension $T_A$.
From the FBD,$T_A=2g$
$=20N$

Draw FBD for block in figure $\left(B\right)$.


Find the value of tension $T_B$.

From FBD block of $2kg$
$2g-T_B=2a\dots \left(i\right)$
For $1kg$ block,$T_B=a\dots \left(ii\right)$
By solving equation $\left(i\right)$ and $\left(ii\right)$, we get
$T_B=\frac{2g}{3}$
$=\frac{20}{3}N$

Draw FBD for block in figure $\left(C\right)$


Find the value of tension $T_C$.

From FBD for block of $1kg$,
$g-T_C=a\dots \left(iii\right)$
For $2kg$ block, $T_C=2a\dots \left(iv\right)$,

By solving equation $\left(iii\right)$ and $\left(iv\right)$,
we get
$T_C=\frac{2g}{3}=\frac{20}{3}N$

Final answer:$\left(b\right)$