When atoms in a covalent bond share electrons unequally (one atoms pulls more than the other), the bond is said to be a polar bond is formed when electrons are unequally shared between two atoms. Polar covalent bonding occurs because one atom has a stronger affinity for electrons than the other (yet not enough to pull the electrons away completely and form an ion).
It is called Analogy. Practically equivalent to structures are those structures in various species which play out a similar capacity, have comparable appearance and structure yet are not developed together; along these lines don't share a typical precursor.
Cases of practically equivalent to structures run from wings in flying creatures like bats, feathered creatures, and creepy crawlies, to balances in creatures like penguins and fish. Plants and different living beings can likewise exhibit similar to structures, for example, sweet potatoes and potatoes, which have a similar capacity of sustenance stockpiling
A physical change is basically a body change so like if a crayon is solid then sits in the sun for a long time it melts away that’s a physical change because it changes its physical appearance
