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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Saurabh 1
a) External geometry is what that we define on the basis of arrangement of atoms that in turn gives the characteristic shape to a respective crystal. So answer should be-- internal arrangements of atoms . b) Isometric dominates in case of symmetric elements and you can observe the decreasing trend from Isometric to Triclinic system(this crystal system do not contain any 2fold, 3fold rotation axis and consist of only 1 fold rotoinversion).