Answer:
Fn = 10 N 
Step-by-step explanation:
Newton's second law: 
∑F = m*a Formula (1) 
∑F : Net force acting on the mass or algebraic sum of the forces in Newton (N) 
m : mass s (kg) 
a : acceleration (m/s²) 
Data
m = 2.0 kg : mass of the object
a = 5.0 m/s² : acceleration of the object
Calculation of the net force (Fn) acting on the mass
We apply the formula (1)
∑F = m*a, ∑F = Fn
Fn = m*a
Fn = (2.0 kg)* (5.0 m/s²)
Fn = 10 N