Questions

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.

It was the Qing Dynasty, who was a Manchu Dynasty whose rule ended in 1911 Chinese revolution.

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

Alum is a common alum, potassium aluminum sulphate K2SO4.Al2SO43.24H2O which makes colloidally suspended impurities in water such as clay to settle down.