Randy is building a house. he wants to put stucco on the outside walls of his house. to make stucco, he needs sand. he lives on the beach, so he decides to use the soil in his backyard. before he can use the sand, he must remove the other substances from the soil. he separates the larger pebbles and other debris from the finer sand by sifting it with wire mesh. randy mixes the sand with concrete and water to make the stucco he needs. which sentence provides the best evidence that randy's backyard soil is a heterogeneous mixture?
(a)-before he can use the soil, he must remove the substances other than sand in the soil.
(b)-to make stucco, he needs sand.
(c)-he separates the larger pebbles and other debris from the finer sand by sifting it with wire mesh.
(d)-randy mixes the sand with concrete and water to make the stucco he needs.

(c)-He separates the larger pebbles and other debris from the finer sand by sifting it with wire mesh.

Explanation:

A mixture is an association of substances that not react between them. It can be homogeneous when it's not possible to see the substances, or heterogeneous when it's possible to see each the substances.

Randy separates the substances of the soil with a wire mesh, so it's possible to define the substances, then the mixture is heterogeneous.

the dependant variable is spilled water

the independent is the heat

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.