Answer:
We know based on the charges of each ion and the fact that they must always sum to 0
Explanation:
Na only has one outer electon to give so it is always +1
Mg has two outer electrons so it always gets +2
Halogens have one "missing" electron in their outer shell so they get a -1
For NaCl (+1) + (-1) = 0
For MgI2 (+2) + 2(-1) = 0
Explanation:
Because when you move the decimal point once, it it equal to 10 and to convert in the metric system, you must multiply or divide by 10. For example, when converting 4 centimeters to millimeters, you can multiply by 10 to get 40 millimeters or you can move the decimal point to the right and add another 0 to get 40.
Complete question is;
A drop of water has a volume of approximately 7 × 10⁻² ml. How many water molecules does it contain? The density of water is 1.0 g/cm³.
This question will require us to first find the number of moles and then use avogadro's number to get the number of water molecules.
<em><u>Number of water molecules = 2.34 × 10²¹ molecules</u></em>
We are given;
Volume of water; V = 7 × 10⁻² ml
Density of water; ρ = 1 g/cm³ = 1 g/ml
Formula for mass is; m = ρV
m = 1 × 7 × 10⁻²
m = 7 × 10⁻² g
from online calculation, molar mass of water = 18.01 g/mol
Number of moles(n) = mass/molar mass
Thus;
n = (7 × 10⁻²)/18.01
n = 3.887 × 10⁻³ mol
from avogadro's number, we know that;
1 mol = 6.022 × 10²³ molecules
Thus,3.887 × 10⁻³ mol will give; 6.022 × 10²³ × 3.887 × 10⁻³ = 2.34 × 10²¹ molecules
Read more at; brainly.in/question/17990661
