The correct option for axial distances and axial angles for hexagonal crystal system is

What is the relationship between the axial angles in an orthorhombic crystal system?

Heat treatment alters the properties of steel due to:

Select the correct option using $T$ (True) or $F$ (False) for the following statements regarding crystal systems:
$(1)$ Crystal system: Cubic,Axial distance: $a = b = c$,Axial angle: $\alpha = \beta = \gamma = 90^{\circ}$,Example: $Cu, KCl$
$(2)$ Crystal system: Monoclinic,Axial distance: $a \neq b \neq c$,Axial angle: $\alpha = \gamma = 90^{\circ}, \beta \neq 90^{\circ}$,Example: $PbCrO_4$
$(3)$ Crystal system: Trigonal (Rhombohedral),Axial distance: $a = b = c$,Axial angle: $\alpha = \beta = \gamma \neq 90^{\circ}$,Example: $CaCO_3, HgS$
$(4)$ Crystal system: Triclinic,Axial distance: $a \neq b \neq c$,Axial angle: $\alpha \neq \beta \neq \gamma \neq 90^{\circ}$,Example: $K_2Cr_2O_7, CuSO_4 \cdot 5H_2O$

In a monoclinic unit cell,the relation of sides and angles are respectively

$A$ unit cell having dimensions $a \neq b \neq c$ and interfacial angles $\alpha \neq \beta \neq \gamma \neq 90^{\circ}$ is known as: