Yes, they are the same. They are equivalent.
I think the answer is (1) Co. Because the element of Cobalt also has 2 electrons at the outer layer which is the same as Calcium. And the outer layer is an important factor which can affect the property of an element.
Symbol "X" represents Nitrogen, phosphorus, and arsenic.as they have five valence electrons in their valance shell.
<h3>What is a Lewis notation?</h3>
A Lewis form is a completely simplified illustration of the valence shell electrons in a molecule. it's miles used to expose how the electrons are organized round man or woman atoms in a molecule. Electrons are proven as dots or for bonding electrons as a line between the 2 atoms.
Lewis systems, also known as electron-dot structures or electron-dot diagrams, are diagrams that show the bonding between atoms of a molecule, and the lone pairs of electrons that can exist within the molecule.A Lewis form is based totally at the idea of the octet rule, wherein atoms percentage electrons in order that every atom has 8 electrons in its outer shell. for example, an oxygen atom has six electrons in its outer shell.
Learn more about valence electrons :-brainly.com/question/371590
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Answer:
b. 54.9%
Explanation:
An emerald gemstone has the formula Be₃Al₂Si₁₆O₁₈. We can find the mass of each element in 1 mole of Be₃Al₂Si₁₆O₁₈ by multiplying the molar mass of the element by its atomicity.
Be: 3 × 9.01 g = 27.03 g
Al: 2 × 26.98 g = 53.96 g
Si: 16 × 28.09 g = 449.4 g
O: 18 × 16.00 g = 288.0 g
Total mass = 818.4 g
The mass percentage of silicon is:
(449.4 g / 818.4 g) × 100% = 54.91%
