Qu$.15$ What are the indices for the Plane $1$ drawn in the following sketch?

Qu$.16$ What are the Miller indices for the Plane shown in the following cubic unit cell?

Qu$.17$ Compute linear density values for $[100]$ for silver $(Ag).$ Express your answer in $n{m}^{-1}.$ Round off the answer to three significant figures.

Qu$.18$ Compute linear density value for $111$ direction for silver $(Ag).$ Express your answer in $n{m}^{-1}.$ Round off the answer to three significant figures.

Qu$.19$ Compute planar density value for $(100)$ plane for chromium $($Cr$).$ Express your answer in $n{m}^{-2}.$

Round off the answer to two significant figures.