Which element is larger in size?(A) Co(B) Ni(C) Cu(D) Zn

In terms of atomic radius, the trend generally increases as you move down a group and decreases as you move across a period from left to right on the periodic table. Among the elements Co (Cobalt), Ni (Nickel), Cu (Copper), and Zn (Zinc):

Co (Cobalt) has an atomic radius of about 149 picometers (pm).
Ni (Nickel) has an atomic radius of about 148 pm.
Cu (Copper) has an atomic radius of about 145 pm.
Zn (Zinc) has an atomic radius of about 142 pm.
Therefore, Zn (Zinc) has the largest atomic radius among the options provided. So, the correct answer is (D) Zn.