Explanation:
The valence electrons within an atom is the number of electrons in its outermost shell.
These electrons are used by an atom to react with one another. They determine the extent to which an atom is ready to combine either by losing, gaining or sharing these electrons.
- Every atom desires to have a completely filled outermost shell.
- Only the elements in group 8 have a complete octet.
- The need to attain stability is driven by the number of electrons in their valence shell.
- Therefore, some atoms are very reactive.
- Those needing one electrons to complete their octet and also those that must lose one electron are very reactive.
Answer:
I would try but i just need points good luck tho
☃️ Chemical formulae ➝ 
How to find?
For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.
Solution:
❍ Molecular weight of
= 2 × 126.90
= 253.80
= 254 (approx.)
❍ Given weight: 12.7
Then, no. of moles,
⇛ No. of moles = 12.7 / 254
⇛ No. of moles = 0.05 moles
⚘ No. of moles of Iodine molecule in the given weight = <u>0.05</u><u> </u><u>moles </u>
<u>━━━━━━━━━━━━━━━━━━━━</u>
Answer: 20) 2365 g
21) 22.39 grams.
22) 29.99 g
Explanation: 20) molarity is the no of moles of solute per unit volume.
We can calculate amount of CaCl2 required to prepare 0.1 M CaCl2 1000 ml solution.
we know that to prepare one ltr of 1 M solution of CaCl2 111 g required
Now consider x gram will require to prepare to
so that comparing above both condition
1000ml ×1M×X g=1000ml×0.1M×111g
X= 11.1 gram
X= 11.1 g of CaCl2
Hence 11.1 g of CaCl2 would be dissolved in 1.0L of a 0.100 M solution of CaCl2
21) How many moles of CaCl₂ in that solution?
;
;
.
What's the mass of that 0.20172 moles of CaCl₂?
Molar mass from a modern periodic table:
Ca- 40.078;
Cl- 35.45.
Molar mass of CaCl₂:
.
Mass of that 0.20172 moles of CaCl₂:
22) its a 3.0m solution so 1 litre of solution contains 3 moles of NaOH, 250ml of solution contains 0.25x39.9971 g/mol, so 250ml of this solution contains 0.75x39.9971=29.99g, or if you round it up 30.0g
