Question

Is the young modulus of rubber greatwr then that of steel ,give the reason?

Answer 1

No, it's not. The opposite is true.

$\frac{F}{A} = Y \frac{\Delta l}{l}$

For the same pressure (on both rubber and steel), we know from real-world observation that rubber deforms more. So change in length is greater for rubber.

And hence, Y must be lesser for rubber than steel, for the equality to hold.