<h2>Answer : Option B) The hematite particles rearrange to form a new substance.</h2><h3>Explanation :</h3>
Hematite particles when gets rearranged to form a new substance, is an example of a chemical change.
As a chemical changes is usually a change where a substance undergoes a chemical change and forms a new substance; which cannot be easily reversed into reactants by any simple physical methods.
In this example the hematite ore forms a new substance by an irreversible chemical change.
The number of atoms of gold in the pure ring are 7.18 × 10²² atoms.
<h3>HOW TO CALCULATE NUMBER OF ATOMS?</h3>
The number of atoms in a substance can be calculated by multiplying the number of moles of the substance by Avogadro's number.
The number of moles in the gold (Au) can be calculated by dividing the mass of gold by its molar mass (196.97g/mol).
no. of moles = 23.5g ÷ 196.97g/mol
no. of moles = 0.119mol
Number of atoms in Au = 0.119 × 6.02 × 10²³
no. of atoms = 7.18 × 10²² atoms.
Therefore, the number of atoms of gold in the pure ring are 7.18 × 10²² atoms.
Learn more about number of atoms at: brainly.com/question/15959704
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Answer:
It is termed a buffering agent
Explanation:
A buffering agent consist of a weak acid and a base that is used to maintain the acidity of a solution after the addition of
another acid or base
A buffer is used to prevent any rapid change in ph
The minimum volume of water needed is 0.28 mL. The solution will have
1.7 mg of phthalic acid remaining in solution.
<em>At 100 °C</em>
Volume of water required = 50 mg HPh × (100 mL water/18 000 mg HPh)
= 0.28 mL water
<em>At 25 °C
</em>
Mass of HPh in solution = 0.28 mL water × (620 mg HPh/100 mg water)
= 1.7 mg HPh
