The half-life of radioactive Radon is $3.8 \ days$. The time at the end of which $1/20^{th}$ of the Radon sample will remain undecayed is ............ $days$ (Given $\log_{10}e = 0.4343$)

The foot of the perpendicular from $(0,2,3)$ to the line $\frac{x+3}{5}=\frac{y-1}{2}=\frac{z+4}{3}$ is

$A$ radioactive material of half-life $T$ was produced in a nuclear reactor at different instants. The quantity produced the second time was twice that produced the first time. If their present activities are $A_1$ and $A_2$ respectively,then their age difference equals:

If $x$ is real,then the minimum value of $y = \frac{x^2-x+1}{x^2+x+1}$ is

What is the unit of $K_p$ for the reaction?
$CS_{2(g)} + 4H_{2(g)} \rightleftharpoons CH_{4(g)} + 2H_2S_{(g)}$

$A$ person running horizontally observes that rain is falling on his head vertically with a speed of $10\,m/s$. When he stops,he observes that the rain is falling at an angle of $30^{\circ}$ with the vertical. Find the speed of the rain with respect to the ground.