The decreasing order of bond dissociation energies of $C-C$,$C-H$,and $H-H$ bonds is:

The vector sum of two forces is perpendicular to their vector difference. In that case,the forces

Which one of the following equations is correct for the reaction $N_{2(g)} + 3H_{2(g)} \longrightarrow 2NH_{3(g)}$?

If the circle $x^2+y^2+8x-4y+c=0$ touches the circle $x^2+y^2+2x+4y-11=0$ externally and cuts the circle $x^2+y^2-6x+8y+k=0$ orthogonally,then $k$ is equal to

The condition that the roots of $x^3-b x^2+c x-d=0$ are in geometric progression is

When a sound wave of wavelength $\lambda$ is propagating in a medium,the maximum velocity of the particle is equal to the wave velocity. The amplitude of the wave is: