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dezoksy [38]
3 years ago
14

A substance undergoes a change. Which of the following indicates that the change was a chemical change?

Chemistry
1 answer:
hoa [83]3 years ago
4 0
The answer is A. <span>The substance changed shape.

There you go!</span>
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A moist red litmus paper is used for testing ammonia gas ,why​
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Answer:

when the red litmus paper is placed in a jar of ammonia, the red litmus paper turns into blue as ammonia gas is basic in nature. It confirms the alkalinity of the ammonia gas.

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Describe the reactions role in earths natural processes?
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energy flow and nutrient cycles ( photosynthesis , food webs, decomposition webs) sediment transport and soil formation. the water cycle. reproduction/ regeneration mechanisms.

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3 years ago
If 38.5 grams of potassium react with excess oxygen gas, how many grams of potassium oxide can be produced? 4K + O2 yields 2K2O
Lera25 [3.4K]

Answer:

46.40 g.

Explanation:

  • It is a stichiometric problem.
  • The balanced equation of the reaction: 4K + O₂ → 2K₂O.
  • It is clear that 4.0 moles of K reacts with 1.0 mole of oxygen produces 2.0 moles of K₂O.
  • We should convert the mass of K (38.5 g) into moles using the relation:

<em>n = mass / molar mass,</em>

n = (38.5 g) / (39.098 g/mol) = 0.985 mole.

<em>Using cross multiplication:</em>

4.0 moles of K produces → 2.0 moles of K₂O, from the stichiometry.

0.985 mole of K produces → ??? moles of K₂O.

∴ The number of moles of K₂O produced = (0.985 mole) (2.0 mole) / (4.0 mole) = 0.4925 mole ≅ 0.5 mole.

  • Now, we can get the mass of K₂O:

∴ mass = n x molar mass = (0.5 mole) (94.2 g/mol) = 46.40 g.

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3 years ago
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The ion will repel the substance because it has more protons than electrons.

Explanation:

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