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Eduardwww [97]
3 years ago
9

Can u please help me I don't understand it and if I don't do it my teacher will get really mad at me pleas

Chemistry
1 answer:
Nana76 [90]3 years ago
6 0

Physical Change: It is a type of change in which matter changes its physical state like shape, size but is not transformed into another substance. It is usually a reversible process.

Chemical Change: It is a type of change in which the rearrangement of atoms of one or more than one substance is involved.  and it changes its chemical composition that is there is a formation of at least one new substance. It is usually an irreversible process.

Now, keeping in mind the definitions, we can easily classify the examples in the question as physical or chemical change.

7. Chemical Change

8. Chemical Change

9. Physical Change

10. Chemical Change

11. Physical Change

12. Physical Change

13. Chemical Change

14. Physical Change

15. Chemical Change

16. Physical Change

17. Chemical Change

18. Chemical Change

19. Physical Change

20. Physical Change

21. Chemical Change

22. Physical Change

23. Chemical Change

24. Chemical Change

25. Physical Change

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Plzzz help me answer this question!!,!
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I can’t see the picture for some reason
7 0
3 years ago
Uranium-267 undergoes alpha decay, what is the mass of the new element?
Firlakuza [10]

Answer:

will this help ?

Explanation:

(108Hs) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 265Hs in 1984. There are 12 known isotopes from 263Hs to 277Hs and 1–4 isomers. The most stable isotope of hassium cannot be determined based on existing data due to uncertainty that arises from the low number of measurements. The confidence interval of half-life of 269Hs corresponding to one standard deviation (the interval is ~68.3% likely to contain the actual value) is 16 ± 6 seconds, whereas that of 270Hs is 9 ± 4 seconds. It is also possible that 277mHs is more stable than both of these, with its half-life likely being 110 ± 70 seconds, but only one event of decay of this isotope has been registered as of 2016.[1][2].

3 0
2 years ago
How many moles of sodium carbonate are contained by 57.3g of sodium carbonate
Lady_Fox [76]

Answer:

\boxed {\boxed {\sf 0.541 \  mol \ Na_2CO_3}}

Explanation:

We are asked to find how many moles of sodium carbonate are in 57.3 grams of the substance.

Carbonate is CO₃ and has an oxidation number of -2. Sodium is Na and has an oxidation number of +1. There must be 2 moles of sodium so the charge of the sodium balances the charge of the carbonate. The formula is Na₂CO₃.

We will convert grams to moles using the molar mass or the mass of 1 mole of a substance. They are found on the Periodic Table as the atomic masses, but the units are grams per mole instead of atomic mass units. Look up the molar masses of the individual elements.

  • Na:  22.9897693 g/mol
  • C: 12.011 g/mol
  • O: 15.999 g/mol

Remember the formula contains subscripts. There are multiple moles of some elements in 1 mole of the compound. We multiply the element's molar mass by the subscript after it, then add everything together.

  • Na₂ = 22.9897693 * 2= 45.9795386 g/mol
  • O₃ = 15.999 * 3= 47.997 g/mol
  • Na₂CO₃= 45.9795386 + 12.011 + 47.997 =105.9875386 g/mol

We will convert using dimensional analysis. Set up a ratio using the molar mass.

\frac {105.9875386  \ g \ Na_2CO_3}{1 \ mol \ Na_2CO_3}

We are converting 57.3 grams to moles, so we multiply by this value.

57.3 \ g \ Na_2CO_3} *\frac {105.9875386  \ g \ Na_2CO_3}{1 \ mol \ Na_2CO_3}

Flip the ratio so the units of grams of sodium carbonate cancel.

57.3 \ g \ Na_2CO_3} *\frac {1 \ mol \ Na_2CO_3}{105.9875386  \ g \ Na_2CO_3}

57.3 } *\frac {1 \ mol \ Na_2CO_3}{105.9875386 }

\frac {57.3 }{105.9875386 } \ mol \ Na_2CO_3

0.5406295944 \ mol \ Na_2CO_3

The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we found that is the thousandth place. The 6 in the ten-thousandth place to the right tells us to round the 0 up to a 1.

0.541 \  mol \ Na_2CO_3

There are approximately <u>0.541 moles of sodium carbonate</u> in 57.3 grams.

6 0
2 years ago
Count the number of bonding pairs and the number of ione pairs around the left chlorine atom
brilliants [131]

Explanation:

I think

Bonding pairs = 4

Lone pairs around the left chlorine atom = 9

7 0
2 years ago
Mostly located on the bottom of the leaf, open close the stomata ​
AlladinOne [14]

Answer:

Guard cells. The guard cells also contain chloroplast.

3 0
3 years ago
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