Answer:

Explanation:
Alkaline earth metals are in group 2. The number of valence electrons of elements in group 2 is 2.
Answer:
you can identify the properties of an element by studying its_____ on the ... between metals and nonmetals on the periodic table are the _____ which have ...
Explanation:
According to the calculation, set I is both the most accurate and most precise.
Exactness is a quality or state of being precise. 2a: comparison accuracy sense: the degree of precision with which an action is carried out or a measurement expressed 2b. The novel was fact-checked for historical authenticity. 2a: conformance to truth, to a standard, or to a model: exactness It is impossible to estimate the number of casualties with accuracy. Let's calculate the precision for the fourth set, considering
Δ1 = ∣(8.41−8.56)∣ g=0.15 g
Δ2 = (8.72−8.56) g=0.16 g
Δ3 = ∣(8.55−8.56)∣ g=0.01 g
Therefore: 
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Answer:
1)Na2O
let the valency of Na is x
2(x)+(2)=0
2x+2=0
2x=-2
x=-1
2)ZnO
let the valency of Zn is x
x+2=0
x=-2
3)Al2O3
let the valency of Al is x
2(x)+3(2)=0
2x+6=0
2x=-6
x=-3
4)MgO
let the valency of Mg is x
x+2=0
x=-2