Answer:early models of telephones were used with a twirl of numbers
Explanation:
Not advanced technology
Chemical,when you light a match stick, you are starting a chain reaction of the substance chemical formula, making it a chemical change
Answer:
B) Protons and Neutrons
Explanation:
In every atom, there is a Nucleus which contains protons and Neutrons. Protons being positive and Neutrons not having a charge (neutral).
Answer:
- <em>The net charge of the ionic compound calcium fluoride is </em><u><em>zero (0).</em></u>
<em>Explanation:</em>
<em>Ionic compounds,</em> such as covalent ones, have zero net charge; this is, they are neutral.
Substances with net positive charge are cations and substances with net negative charge are anions.
The charges in the <em>ionic compound calcium flouride</em> are distributed in this way:
- Calcium charge: Ca²⁺: this is, each calcium ion has a 2 positive charge
- Fluoride charge: F⁻: each fluoride ion has a 1 negative charge.
- Then, the <em>net charge</em> is: 1 × (2+) + 2 × (1-) = +2 - 2 = 0.
So, a two positve charge, from one calcium ion, is equal to two negative charges, from two fluoride tions, yielding a <u>zero net charge</u>.
Answer : The concentration of solution is, 8.53 M.
Explanation :
As we are given, 45.0 mass % solution of ethanol in water that means 45.0 g of ethanol present in 100 g of solution.
First we have to calculate the volume of solution.
Now we have to calculate the molarity of solution.
Mass of 
= 45.0 g
Volume of solution = 114.5 mL
Molar mass of = 46.07 g/mole
Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.
Formula used :
Now put all the given values in this formula, we get:
Therefore, the concentration of solution is, 8.53 M.
