Which of the following prevents the collapsing of the trachea?

Thermite is a mixture of $X$ parts of ferric oxide and $Y$ parts of aluminium powder. $X, Y$ respectively are

When work is done on a body by an external force,its

Which is the lightest gas?

What will be the angular width of the central maxima in Fraunhofer diffraction when light of wavelength $6000 \, \mathring{A}$ is used and the slit width is $12 \times 10^{-5} \, cm$? (in $rad$)

Suppose that a random variable $X$ follows a Poisson distribution. If $P(X=1) = P(X=2)$,then $P(X=5)$ is equal to: