Which of the following is used as an antacid?

If the change in the value of $g$ at a height $h$ above the surface of the earth is the same as at a depth $x$ below it,then (both $x$ and $h$ being much smaller than the radius of the earth)

$75 \ mL$ of $0.2 \ M \ HCl$ is mixed with $25 \ mL$ of $1 \ M \ HCl$. To this solution,$300 \ mL$ of distilled water is added. What is the $pH$ of the resultant solution?

$\int \frac{\sin x+8 \cos x}{4 \sin x+6 \cos x} d x$ is equal to

Every planet revolves around the sun in an elliptical orbit. Consider the following statements:
$A.$ The gravitational force acting on a planet is inversely proportional to the square of the distance from the sun.
$B.$ The gravitational force acting on a planet is inversely proportional to the product of the masses of the planet and the sun.
$C.$ The centripetal force acting on the planet is directed away from the sun.
$D.$ The square of the time period of revolution of a planet around the sun is directly proportional to the cube of the semi-major axis of the elliptical orbit.
Choose the correct statements from the options given above:

Bamboo and grasses elongate by the activity of ......