Step-by-step explanation:
Given that,
Mass, m = 343 g = 0.343 kg
Force constant, k = 3 N/m
Displacement in the mass from equilibrium position is 4 cm
(a) The time period of the mass that oscillates is given by :

(b) Firstly lets find the angular frequency. It is given by :

Now the maximum speed of the mass in SHM is given by :

(c) The maximum acceleration of the mass is given by :

Hence, this is the required solution.