CHEM 112/6.0 (see first year Chemistry)
MATH 121/6.0 or MATH 120/6.0 (calculus: see What MATH course should I take?)
PHYS 106/6.0 or PHYS 104/6.0 (Physics: see What PHYS course should I take?)
MATH 112/3.0 or MATH 111/6.0 (linear algebra: see What MATH course should I take? Note that this requirement may be deferred until your second year.
For a list of all electives see here