| LIST I | LIST II | ||
| A. | Mass of alpha particle | I. | 1.00727 u | 
| B. | Mass of proton | II. | 4.00260 u | 
| C. | Mass of neutron | III. | 0.00055 u | 
| D. | Mass of electron | IV. | 1.00866 u | 
Rearrange the following parts to form a meaningful and grammatically correct sentence: 
P. a healthy diet and regular exercise 
Q. are important habits 
R. that help maintain good physical and mental health 
S. especially in today's busy world