what is the function of the soft iron core in a moving coil galvanometer
Your friend has answered this question very well. Keep it up Asmita!
The soft iron core is spherical if the coil is circular and cylindrical if the coil is rectangular. It makes the magnetic field linked with the coil to be a radial field ie the plane of the coil in all positions remains parallel to the direction of magnetic field.
see the diagram of the moving coil galvanometer below:
. Therefore torque produced = NIBAcos Ө,
where Ө =00.
Hence torque=NIBA,
ie maximum torque is produced.
Also the retentivity of soft iron core is low, which increases the sensitivity of the galvanometer ie the moment current becomes 0 , the galvanometer will show 0 deflection.