Question

perpendicular to x-axis is not defined.If true enter 1 else 0.

Answer 1

Line perpendicular to $x-$ axis is the $y-$ axis.
Inclination of $y-$ axis is ${90}^0$.
Hence, inclination of a line which is perpendicular to x-axis is ${90}^0$.

Slope of line with an inclination $\theta =tan\theta$.
Hence, slope of line, with inclination $\theta ={90}^0$ is tan ${90}^0=$ not defined.