Answer:- The formula 
tells us that one formula unit of this compound is composed of one calcium atom, two nitrogen atoms, and six oxygen atoms.
Explanations:- Subscripts tell us about the number of atoms of the element for which they are used. For example, here the subscript of Ca is one, it means there is one calcium atom in the given one formula unit.
When we have subscripts inside and outside the parenthesis then they are multiplied and the outside subscript is considered for all the atoms present inside the parenthesis.
Here, for the given chemical formula, the subscript of N is 1 and the subscript present outside is 2. So, 1 x 2 = 2 and for oxygen, 3 x 2 = 6
So, we have one calcium atom, two nitrogen atoms and six oxygen atoms for one formula unit of given compound.
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%
Answer is (1) - N
<em>Explanation:</em>
I think the given chart is electronegativity chart.
Electronegativity is a
value that tells us how an atom can attract electrons towards itself. <span><u>If the electronegativity is
high, then the attraction to the electrons is high unless the attraction to the
electrons is low. </u>
Electronegativity increases from left to right of the periodic table and decreases from up to down.
Hence, highest electronegative atom is F which has 4.0 and lowest electronegative atoms are Cs and Fr (0.7).
The electronegativity values for given atoms are
N - 3.0
Na - 0.9
P - 2.1
Pt - 2.2
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