European cuckoo birds lay their eggs in the nest of other bird species, allowing the other birds to raise their young. the cuckoo birds are therefore:

thinking it would be physical characteristics

in a chemical reaction, the atoms and molecules produced by the reaction are called products. no new atoms are created, and no atoms are destroyed. in a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.