The defining symmetry characteristics of the crystals belonging to the cubic system is :
MH SET - 2019, SET Exam - 2019,
Answer: B
The defining symmetry of the cubic system is four axes of three-fold symmetry.
All five crystal classes of the cubic (isometric) system have four three-fold rotation axes, lying along the body diagonals of the cube. That is the element shared by every cubic class, so it defines the system.
Three four-fold axes are present only in the most symmetrical cubic classes; others have two-fold axes in those directions. Oblique and vertical mirror planes are not present in every class, and four two-fold axes alone do not define the cubic system.
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