Answer:

Explanation:
We are asked to find the density of a brick. Density is a substance's mass per unit volume. The formula for calculating density is as follows.

The mass of the brick is 100 grams and the volume is 25 cubic centimeters.
Substitute the values into the formula.

Divide.

The density of the brick is <u>4 grams per cubic centimeter.</u>
Answer:
Elements only contain one type of atoms while compounds contain two or more types of atoms.
Explanation:
An example of an element is sodium --> Na (only Na atoms)
An example of a compound can be water --> H2O (contain H and O atoms)
*But the particles within a compound are all the same.
Answer:
= 0.014 g of BaCO3
Explanation:
Let x = mol/L of BaCO3 that dissolve.
This will give;
x mol/L Ba2+ and x mol/L CO32-
But;
Ksp = 5.1x10^-9.
Therefore;
Ksp = 5.1 x 10^-9 = (x)(x)
Thus;
x = molar solubility
= √ (5.1 x 10^-9)
= 7.1 x 10^-5 M
Therefore;
Mass BaCO3 = 7.1 x 10^-5 M x 1 L x 197.34 g/mol
= 0.014 g
It’s C because the oak trees create a population