<u>Answer:</u> The unknown element X is calcium.
<u>Explanation:</u>
We are given:
An ionic compound having chemical formula = 
The given compound is a neutral compound and in a neutral compound, the oxidation states are exchanged.
We know that:
Oxidation state of chlorine ion = -1
So, the oxidation state of X ion will be +2
Atomic number is defined as the number of protons or electrons that are present in a neutral atom.
Atomic number = number of protons = number of electrons
Number of electrons = Number of protons - charge
We are given:
Mass number = 40
Number of electrons = 18
So, number of protons = Number of electrons + Charge
Number of protons = 18 + 2 = 20 = Atomic number
Hence, the unknown element X is calcium having atomic number '20'
Answer:
If a mineral with a density of 6 g/cm3 is broken into 3, the density of each new piece is 6 
Explanation:
Density is a quantity that allows us to measure the amount of mass in a certain volume of a substance. In other words, density is the property that matter, whether solid, liquid or gas, has to compress into a given space, the amount of mass per unit volume.
As density is a physical property of matter that is defined as the ratio of an object's mass to its volume, each material or substance has its own density regardless of its size because the ratio between mass and volume is the same.
<u><em>If a mineral with a density of 6 g/cm3 is broken into 3, the density of each new piece is 6 </em></u><u><em></em></u>
Answer:
Endothermic. The energy is flowing into the molecules causing them to break apart and the ice pop change state.
Pure, crystalline solids have a characteristic melting point, the temperature at which the solid melts to become a liquid. The transition between the solid and the liquid is so sharp for small samples of a pure substance that melting points can be measured to 0.1oC. The melting point of solid oxygen, for example, is -218.4o<span>C.</span>
