Question on: JAMB Chemistry - 1990

.....................P....Q.....R......S

Proton..............13....16....17.....19

Electron............13....16....17.....19

Neutron.............14....16....35.....20

Which of the four atoms P,q,R and in S in the above data can be described by the following properties relative atomic mass is greater than 30 but less than 40; it has an odd atomic number and forms a unipositive ion in solution?