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

The body of the ovule is fused with the funicle at:

If the area of an equilateral triangle inscribed in the circle $x^2 + y^2 + 10x + 12y + c = 0$ is $27\sqrt{3}$ sq. units,then $c$ is equal to:

$A$ person observes the top of a tower from a point $A$ on the ground. The angle of elevation of the tower from this point is $60^{\circ}$. He moves $60 \ m$ in the direction perpendicular to the line joining $A$ and the base of the tower. The angle of elevation of the tower from this new point is $45^{\circ}$. Then,the height of the tower (in metres) is

Assertion $A$: An astronaut inside a massive spaceship orbiting around the Earth will experience a finite but small gravitational force.
Reason $R$: The centripetal force necessary to keep the spaceship in orbit around the Earth is provided by the gravitational force between the Earth and the spaceship.

The function $f(x) = x e^{-x}, \forall x \in R$ attains a maximum value at $x$ equal to