Which of the following diseases is spread through the sputum of a patient?

What is the correct order of occurrence ($\%$ by weight) in air of $Ne, Ar$ and $Kr$?

Which of the following is a characteristic of $Pteridophytes$?

If the lines,joining the origin to the points of intersection of the curve $2x^2 - 2xy + 3y^2 + 2x - y - 1 = 0$ and the line $x + 2y = k$,are at right angles,then $k^2$ equals

$DCMU$ is an inhibitor of

Let $f:[-1, 3] \to R$ be defined as $f(x) = \begin{cases} |x| + [x], & -1 \le x < 1 \\ x + |x|, & 1 \le x < 2 \\ x + [x], & 2 \le x \le 3 \end{cases}$ where $[t]$ denotes the greatest integer function. Then $f$ is discontinuous at: