Questions

The number of bonds between a pair of atoms is called the bond order.

Bond orders can be calculated from Lewis structures, which are the heart of the valence-bond model. Oxygen, for example, has a bond order of two.

When there is more than one Lewis structure for a molecule, the bond order is an average of these structures. The bond order in sulfur dioxide, for example, is 1.5  the average of an S-O single bond in one Lewis structure and an S=O double bond in the other.

In molecular orbital theory, we calculate bond orders by assuming that two electrons in a bonding molecular orbital contribute one net bond and that two electrons in an antibonding molecular orbital cancel the effect of one bond. We can calculate the bond order in the O₂ molecule by noting that there are eight valence electrons in bonding molecular orbitals and four valence electrons in antibonding molecular orbitals in the electron configuration of this molecule. Thus, the bond order is two.

The gram formula mass is nothing but molar mass.

Composition :

Symbol      Element       Atomic weight       Atoms
   

     P         Phosphorus       30.973762               1       = 30.973
   

     O         Oxygen             15.9994                  4       =  63.998
   

     N         Nitrogen            14.0067                  3       =  42.020
   

     H         Hydrogen          1.00794                  12      =  12.096

Total   =  30.973+63.998+42.020+12.096 = 149.087

A Skeleton is what is whole but incomplete, have no eyes, yet can see. We can see, and see right through it. The largest part is one fourth of what it once was i.e body.

Genetic drift or allelic drift is the change in the relative frequency in which a gene variant (allele) occurs in a population due to random sampling and chance.

When is genetic drift a major factor in evolution is

* When there is low gene flow.

* When there is no selective pressure.

* When there is a bottleneck.

Fear of places and situations that might cause panic, helplessness or embarrassment is called Agoraphobia. 

Fear of crossing road causes some panic in them and comes under Agoraphobia.