Keystone species deserve protection because these

In which of the following reactions is hydrogen gas not liberated?

Which of the following is the correct decreasing order of thermal stability of alkaline earth metal carbonates?

The electric field component of an electromagnetic wave in vacuum is given as $\vec E = 3\cos(1.8y + 5.4 \times 10^8 t)\hat i$. Its direction of propagation and wavelength are:

Two identical blocks $A$ and $B$,each of mass $m$,resting on a smooth floor,are connected by a light spring of natural length $L$ and spring constant $k$. $A$ third identical block $C$ (mass $m$) moving with a speed $v$ along the line joining $A$ and $B$ collides with $A$. The maximum compression in the spring is proportional to:

The eccentricity of the conic $36x^2 + 144y^2 - 36x - 96y - 119 = 0$ is