In a longitudinal section of a root,starting from the tip upward,the four zones occur in the following order:

Which of the following is a medicinal plant?

If $\frac{d^2y}{dx^2} = 0$,then

$A$ small quantity of solution containing $Na^{24}$ radionuclide of activity $1$ $\mu Ci$ is injected into the blood of a person. $A$ sample of the blood of volume $1\, cm^3$ taken after $5\, hours$ shows an activity of $296$ disintegrations per minute. What will be the total volume of the blood in the body of the person? Assume that the radioactive solution mixes uniformly in the blood of the person. (Take $1\, curie = 3.7 \times 10^{10}$ disintegrations per second and $e^{-\lambda t} = 0.7927$; where $\lambda$ is the disintegration constant).

The energy of an electron in the $n^{th}$ orbit of a hydrogen atom is expressed as $E_n = \frac{-13.6}{n^2} \text{ eV}$. The shortest and longest wavelengths of the Lyman series are:

The locus of the centre of a circle which passes through the origin and cuts off a chord of length $4$ units from the line $x=3$ is