Dark is just absence of light like if the re container a and container b u nee to pour hcl from a to so a has hcl while b has absence of hcl
tell me if u need more examples.hope it helps
1- Molar solutions: based on number of moles of chemical in 1 litre of solution
2- Weight % solution: the weight of chemical divided by the total weight of the solution (chemical + water) and multiplied by 100.
Element with an atomic number of 58 is actually Cerium, so the symbol should be Ce, not Co because that is Cobalt which has an atomic number of 27. With that being said, the notation for isotopes is the symbol of the element with a superscript and a subscript that are aligned. The superscript represents the mass number.
Mass number = protons + neutrons = 58 + 33 = 91
The subscript is the atomic number which is 58. The notation is written in the picture attached.
2.48 grams.
<h3>Explanation</h3>
Start by finding the formula mass for cobalt (II) chloride and cobalt (II) chloride hexahydrate.
As a transition element in the middle d-block of the periodic table, cobalt can form ions with a plurality of charges. It is thus necessary to indicate its charge in systematic names of cobalt-containing formula.
The cation "cobalt" in the systematic name of the salt has the Roman numeral "(II)" attached to it in brackets. As a metal, cobalt forms positively-charged ion. The one here thu has charge of +2.
Chloride ions have charges -1. Charges cancel out to produce neutral compounds. Each cobalt cation in this salt would thus pair with two chloride anions. Hence the empirical formula:
.
The prefix "<em>hexa-</em>" in the name cobalt (II) chloride <em>hexa</em>hydrate indicates that every formula unit of this salt contains six units of water. The hydrated salt thus has an empirical formula of
.
Given the relative atomic mass for each of the elements, as seen on a modern periodic table of the elements:
- Cobalt- 58.93

- Chloride- 35.45
- Hydrogen- 1.008

- Oxygen- 16.00

Thus the formula mass of each compound
- Cobalt (II) chloride
- 129.83 
- Cobalt (II) chloride hexahydrate
- 262.12 
Cobalt (II) chloride hexahydrate
decomposes under heat to produce cobalt (II) hexahydrate and water. Hence the equation:

Therefore
- Molar ratio:

- Mass ratio:

The mass ratio
indicates that 262.12 grams of cobalt (II) chloride hexahydrate decomposes to produce 129.83 grams of its corresponding anhydrous salt. Accordingly, heating 5.00 grams of the hexahydrate would produce 2.48 grams of its anhydrate.