Two elements in the second transition series (y through cd ) have three unpaired electrons in their 3+ ions. what elements fit this description?

The elements that have 3 unpaired electrons in their +3 oxidation states are Molybdenum and Palladium.

Explanation: The elements in the second transition series are:

Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag) and Cadmium (Cd).

The electronic configuration of these elements are:

            ;      

          ;      

          ;      

          ;    

           ;    

           ;    

           ;    

         ;    

          ;    

         ;    

From the above configurations of the elements in their +3 ionic state, the elements having 3 unpaired electrons are Molybdenum and Palladium.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer