A circular loop of area 1 cm², carrying a current of 10 A, is placed in a magnetic field of 0.1 T perpendicular to the plane of the loop. The torque on the loop due to the magnetic field is :

zero

Torque is given by $\tau = nI \vec{A} \times \vec{B}$

Since both area vector and magnetic field is along the same direction hence torque will be zero.