Which particle makes the atom an unstable isotope?

Determine the reaction and balance the following equations urgent due in the morning

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

Astudent completes a titration by adding 12.0 milliliters of naoh(aq) of unknown concentration to 16.0 milliliters of 0.15 m hcl(aq). what is the molar concentration of the naoh(aq)? 1)5.0 m 2)0.20 m 3)0.11 m 4)1.1 m