The ratio of anion radius to cation radius of a crystal is $10: 9.3$. Then,the coordination number of the cation in the crystal is

Assertion $(A)$: The boiling points of noble gases increase from $He$ to $Xe$.
Reason $(R)$: The interatomic van der Waals' attractive forces increase from $He$ to $Xe$.
The correct answer is:

If one of the lines in the pair of straight lines given by $4x^2+6xy+ky^2=0$ bisects the angle between the coordinate axes,then $k \in$

In an interference experiment,the third bright fringe is obtained at a point on the screen with light of wavelength $700 \, nm$. What should be the wavelength of the light source in order to obtain the $5$th bright fringe at the same point (in $, nm$)?

The limiting friction between two bodies in contact is independent of

The point of intersection of the lines $l_1: r(t)=(i-6j+2k)+t(i+2j+k)$ and $l_2: R(u)=(4j+k)+u(2i+j+2k)$ is