Answer: The ion is
. The chemical symbol of the noble gas this ion is isoelectronic with Kr.
Explanation:
The given electronic configuration is,

The number of electrons = 2 + 2 + 6 + 2 + 6 = 18 electrons
As the ion has a charge of +2 , that means it has lost two electrons so the the neutral element will have 2 more electrons i.e 18+2 = 20. The element has atomic number of 20 and the element will be Calcium with electronic configuration of

Thus the symbol of ion is
. the nearest noble gas with 18 electrons is Krypton with symbol Kr.
The dye molecules move in a directed way from high to low concentration
Explanation:
The statement that best describes the motion of dye molecule in water is directed from a region of high to low concentration. The motion of the particles of the dye in water is described as diffusion:
- diffusion is the movement of molecules of a substance from one position to another.
- diffusion occurs from a region of high concentration to that of a low concentration.
- the dye in the water solution causes an increase in concentration of an area where it is dropped.
- this causes the particles to spread outward in the solution.
- a concentration gradient is set up between the two parts of the solution.
- this gradient facilitates the movement of the dye particles.
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Mg(OH)2
Mg: 1
O: 2
H: 2
Mg. O H
24.3g 32g. 2
58.3g in 1 mol of Mg(OH)2
3.2mol of Mg(OH)2 x 58.3g of Mg(OH)2
-------------------------
1 mol of Mg(OH)2
= 186.56 g of Mg(OH)2 in 3.2 mols of Mg(OH)2
(1) A,B,C is your answer, a decreasing pH means there is a higher H+ concentration