Does the life history of every individual exhibit the structural features of its ancestors?

This states that an organisms during its development tends to repeat the evolutionary history of its ancestors

Which one of the following halogens does not exhibit positive oxidation state in its compounds?

How do you distinguish a 'hirudinéaun' from the rest of the annelids, based on the morphological features pertaining to metamerism ? How does the coelom of a leech differ from the coelom of an earthworm with reference to its contents ?

Gallium does not exhibit +2 oxidation state, but the emperical formula of its chloride is GaCl_2 Explain.

Covalent molecules formed by heteroatoms bound to have some ionic character. The ionic character is due to shifting of the electron pair towards A or B in the molecule AB. Hence, atoms acquire small and equal charge but opposite in sign. Such a bond which has some ionic character is described as polar covalent bond. Polar covalent molecules can exhibit dipole moment. Dipole moment is equal to the product of charge separation, q and the bond length, d for the bond. The unit of dipole moment is Debye. One Debye is equal to 10^(-18) esu cm. Dipole moment is a vector quantity. It has both magnitude and direction. Hence, dipole moment of molecules depends upon the relative orientation of the bond dipoles, but not on the polarity of bonds alone. A symmetrical structure shows zero dipole moment. Thus, dipole moments help to predict the geometry of the molecules. Dipole moment values can be used to distinguish between cis-and traps-isomers, ortho-, meta-and para-forms of a substance, etc. The percentage of ionic character of a bond can be calculated by the application of the following formula : % " ionic character " = ("Experimental value of dipole moment ")/("Theoretical value of dipole moment ") xx 100 A diatomic molecule has a dipole moment of 1.2 D. If the bond length is 1.0 xx 10^(-8) cm, what fraction of charge does exist on each atom?

A vinyl polymer is a life saving substance as blood plasma. Write the empirical and structural formula of its monomer.