The notochord is a flexible, rod like supporting structure, running dorsally for almost the whole length of the body. This is a distinctive feature of a chordate / animals with a back bone (vertebral column) Such animals belong to phylum Chordata.
Yes. An example is Methyl Alcohol, absorbs water. (CH3OH) Two elements can form different types of bonds and end up with different compounds. There is a small amount of elements. There is a bigger number of compounds.
