The main pieces of evidence that an exothermic reaction has occurred is an increase in temperature due to the release of energy, a release of energy in the form of light, or a release of gas.
Answer:
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Explanation:
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Answer:
0.004522 moles of hydrogen peroxide molecules are present.
Explanation:
Mass by mass percentage of hydrogen peroxide solution = w/w% = 3%
Mass of the solution , m= 5.125 g
Mass of the hydrogen peroxide = x



Mass of hydregn pervade in the solution = 0.15375 g
Moles of hydregn pervade in the solution :

0.004522 moles of hydrogen peroxide molecules are present.
Answer:
<h3>The answer is option B</h3>
Explanation:
To calculate the number of atoms we must first calculate the number of moles
Molar mass = mass / number of moles
number of moles = mass / Molar mass
Molar mass (K) = 39.10mole
mass = 2.10g
number of moles = 2.10/ 39.10
= 0.0537mol
After that we use the formula
N = n × L
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10^23 entities
Number of K atoms is
N = 0.0537 × 6.02 × 10^13
<h3>N = 3.23×10^22 atoms of K</h3>
Hope this helps you.