If an element is found in group 2 on the periodic table, you can infer that it has two valence electrons, it has a high reactivity (alkaline earth metals), and the oxidation number is 2+
Three signs that a chemical change has taken place is 1) color change 2) formation of gas bubbles 3) a change in temperature ( if you have ever bleached your hair the reason why it is warm to the touch is because of a chemical reaction)
<u>Answer:</u>
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<u>Explanation:</u>
Balancing is making the number of atoms of each element same on both the sides (reactant and product side).
To find the number of atoms of each element we multiply coefficient
subscript
For example
contains
5 × 1 = 5 ,Ca atoms and
5 × 2 = 10, Cl atoms
If there is a bracket in the chemical formula
For example
we multiply coefficient × subscript × number outside the bracket to find the number of atoms
(Please note: 3 is the coefficient, and if there is no number given then 1 will be the coefficient )
So
3 × 3 = 9 , Ca atoms
3 × 1 × 2 = 6, P atoms
3 × 4 × 2 = 24, O atoms are present.
So
Let us balance the equation given

(balanced equation)
<u>Reactant side </u> <u>Elements</u> <u>Product side
</u>
1 Ba 1
2 Cl 2
4 H 4
2 O 2
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Balanced!!!
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this aint in question form so can answer......
Not sure, is it <span>:
</span>B.
<span> 1.9 3 1027 NiCl2
formula units</span>