The lungs are covered by which of the following?

Choose the incorrect order of the given properties.

The equation of the circle concentric with the circle $x^2+y^2-6x+12y+15=0$ and having double its area is

If pairs of straight lines $x^2-2 p x y-y^2=0$ and $x^2-2 q x y-y^2=0$ be such that each pair bisects the angle between the other pair,then

The intensity of the electric field required to keep a water drop of radius $10^{-5} \, cm$ just suspended in air when charged with one electron is approximately:

In which of the following molecules/ions are all the bonds not equal?