The value of $x$,where $x>0$ and $\tan \left(\sec ^{-1}\left(\frac{1}{x}\right)\right)=\sin \left(\tan ^{-1} 2\right)$ is

Carbon,silicon,and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by $(Eg)_C$,$(Eg)_{Si}$,and $(Eg)_{Ge}$ respectively. Which one of the following relationships is true in their case?

What is the method of using predators for the control of pests called?

One mole of alkene $\underline{X}$ on ozonolysis gave one mole of acetaldehyde and one mole of acetone. The $IUPAC$ name of $\underline{X}$ is

$A$ cell is connected between the points $A$ and $C$ of a circular conductor $\text{ABCD}$ of center $O$ with angle $\angle AOC = 60^{\circ}$. If $B_1$ and $B_2$ are the magnitudes of the magnetic fields at $O$ due to the currents in arc $\text{ABC}$ and arc $\text{ADC}$ respectively,the ratio $\frac{B_1}{B_2}$ is

The acute angle between the two lines whose direction ratios $(l, m, n)$ satisfy the equations $l+m-n=0$ and $l^2+m^2-n^2=0$ is