Which of the following is a scalar quantity?

If $x > 0, y > 0, z > 0, xy + yz + zx < 1$ and if $\tan^{-1} x + \tan^{-1} y + \tan^{-1} z = \pi$,then $x + y + z$ equals to

If the sum of the distances of a point $P$ from two perpendicular lines in a plane is $1$,then the locus of $P$ is a

The velocities of two particles $A$ and $B$ are $0.05 \ ms^{-1}$ and $0.02 \ ms^{-1}$ respectively. The mass of $B$ is five times the mass of $A$. The ratio of their de-Broglie's wavelength is

What is the current through an ideal $P-N$ junction diode shown in the figure below? (in $mA$)

The pelvic girdle of birds is attached to a complex structure formed by the fusion of the last thoracic,all lumbar,and the first five caudal vertebrae. This structure is called: