There are 4 things that are evidence of a chemical change.
1)Change in color
2)Change in shape (gas being let out)
3)Change in temperature
4)Change in smell
Burning wood is a chemical change because it has a change in color, and shape.
<u>Answer:</u> The uncertainty in the velocity of oxygen molecule is 
<u>Explanation:</u>
The diameter of the molecule will be equal to the uncertainty in position.
The equation representing Heisenberg's uncertainty principle follows:

where,
= uncertainty in position = d = 
= uncertainty in momentum = 
m = mass of oxygen molecule = 
h = Planck's constant = 
Putting values in above equation, we get:

Hence, the uncertainty in the velocity of oxygen molecule is 
<span>(4) The dissolving of the LiBr(s) in water is an exothermic process</span>
Answer: The atomic weight of the metal would be 85.47.
Explanation:
Mass of isotope 1 of metal = 84.9118
% abundance of isotope 1 of metal = 72.15% =
Mass of isotope 2 of metal= 86.9092
% abundance of isotope 2 of metal = 27.85% =
Formula used for average atomic mass of an element :

Therefore, the atomic weight of the metal would be 85.47.
Answer:
It'll be the same as 58.44 amu. This is because of the law of conservation of mass which states that total mass of reactants is always equal to the total mass of products formed.
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