When $NaCl$ is dissolved in water,the sodium ion becomes

If $m_1$ and $m_2$ are the roots of the equation $x^2+(\sqrt{3}+2) x+(\sqrt{3}-1)=0$,then the area of the triangle formed by the lines $y=m_1 x, y=m_2 x$ and $y=c$ is:

$A$ polygon has $54$ diagonals. Then,the number of its sides is

In a $YDSE$,bichromatic light of wavelengths $\lambda_1 = 400\, nm$ and $\lambda_2 = 560\, nm$ are used. The distance between the slits is $d = 0.1\, mm$ and the distance between the plane of the slits and the screen is $D = 1\, m$. The minimum distance between two successive regions of complete darkness is.......$mm$.

The phenomenon of 'industrial melanism' demonstrates:

The minimum deviation produced by a hollow prism filled with a certain liquid is found to be $30^o$. The angle of refraction is also found to be $30^o$. The refractive index of the liquid is