JEE Advanced Model Paper 5 with solutions for online practice

One end of an elastic string of natural length I0 and force constant k N/m is fixed to a point on a smooth horizontal surface and the other end is attached to a particle of mass m lying on the surface. The particle is pulled to a distance 2I0 from thefixed point and then released from rest. Time period (in s) for complete oscillation of the particle will be n. Find the value of n. (m = 1 kg , √k - 4 = 2π)