In a surface wave (like water) the water goes up and down, but the wave travels across (parallel to) the surface.
Answer:
The correct answer option is C
Explanation:
In a balanced chemical reaction mass of the reactant are always equal to mass of the products. Also known as Law of Conservation of Mass which states that " mass can nor be created nor be destroyed in a chemical reaction."
So, the mass of the reactant will be equal to the mass of products.That is 120 grams.
Hence, the correct answer option(C).
For a concave mirror, the radius of curvature is twice the focal length of the mirror:

where f, for a concave mirror, is taken to be positive.
Re-arranging the formula we get:

and since the radius of curvature of the mirror in the problem is 24 cm, the focal length is