Moles= mass divided by molar mass
Molar mass= 12.01(4) + 1.01(10)
= 58.14g/mol
Moles=14.5g / 58.14g/mol
=0.249
Therefore there are approx 0.249 moles in a 14.5g sample of C4H10
The formula for acceleration if rearranged based on the force equation is- force over mass. So 5000/1200=4.16
Your answer is 4 m/s squared.