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lesya692 [45]
3 years ago
15

some constellations, such ad Ursa Minor, are visible in the sky year-round; other contellations appear for only part of the year

. explain why this happens.
Chemistry
1 answer:
worty [1.4K]3 years ago
5 0
While most constellations are only visible to us in different seasons, some are always there 24/7/365 because they are positioned close to the Polar Axis, or the Polaris.
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Density is a physical property that is determined by dividing the mass of a given amount of a substance by its volume.

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Why is a homogeneous mixture not considered a pure substance? Question 6 options: A pure substance can be separated by physical
krok68 [10]

1. Why is a homogeneous mixture not considered a pure substance?

<u><em>Answer:</em></u>

  • A pure substance can be separated by chemical means, while a mixture can be separated by physical means.

2. What is true if mass is conserved in a reaction?

<em><u>Answer:</u></em>

  • There are equal numbers of atoms on both sides.

3. <em>Methane reacts with oxygen then what are the products?</em>

<u><em>Answer:</em></u>

  • carbon dioxide and water

4. Which one of the following is not a homogeneous mixture?

<u><em>Answer:</em></u>

  • vegetable soup

5. The substance is not uniform in appearance and each part of the mixture contains a combination of different ingredients in different ratios.

<u><em>Answer:</em></u>

  • heterogeneous mixtures

6. If a solution is saturated, which of these is true?

<u><em>Answer:</em></u>

  • More solvent can be dissolved

7. Which of these substances are molecules?

<u><em>Answer:</em></u>

  • All compounds are molecules but not all molecules are compounds. Molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element. So correct option is 3 and 4.

8. What makes a solution a homogeneous mixture?

<u><em>Answer:</em></u>

  • It is uniform in composition.

9. When a solute is added to a solution, why does it remain homogeneous?

<em>Answer:</em>

  • The solute dissolves.

10. The chemical formula of glucose is C6H12O6, so it is classified as a(n)

<u><em>Answer:</em></u>

  • pure substance.

11. <em>How many chlorine (Cl) atoms would be in 4 molecules of salt (4 NaCl)?</em>

<u><em>Answer:</em></u>

  • 4

12. <em>In a solution of salt and water, which component is the solute?</em>

<u><em>Answer:</em></u>

  • Salt

13. These substances are all   H2O2,   Li , NaCl , O2

<u><em>Answer:</em></u>

  • Pure Substances

14. If you have 5 grams of product after a chemical reaction, how many grams of reactants did you have at the start of the reaction?

<em>Answer:</em>

  • 5

15. What is the difference between a compound and a mixture?

<u><em>Answer:</em></u>

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16. A firework exploding would be an example of a(n) ________.

<u><em>Answer:</em></u>

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17. If Lavoisier heated 100 grams of powdered mercuric oxide to produce 93 grams of liquid mercury, how much oxygen would be released?

Solution

                       2HgO ==> 2Hg + O2

Mass of HgO = 100 g

Molar mass of HgO = 216.59 g/mol

Moles = mass/molar mass = 0.46 moles

From balance chemcial equation

   HgO :  O2

      2  =    1

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mass of O2 = moles× molar mass = 0.23 × 32 = 7.36 g

18. Using the Law of Conservation of Matter, determine the number of grams of iron sulfide (FeS) that will be produced in this reaction.

<em><u>Solution</u></em>

                         12g Fe + 64g S → _____ g FeS

  • According to Law of Conservation of Matter, The total mass of reactant is equal to total mass of  product , so the number of grams of iron sulfide (FeS) that will be produced in this reaction as follow.

                              12 + 64 = 76 g of FeS


Hope this Help.

 





3 0
3 years ago
Read 2 more answers
PLZ HURRY
Aliun [14]

Hello.

The answer is: False

The current theory of the formation of our solar system is that the planets formed more or less in their present orbits and they were made balls of gas but they were never comets captured by the sun.

Have a nice day

5 0
3 years ago
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