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
Explanation:
The problem basically wants you to find a way to convert between the number of atoms present in the sample and the number of moles they are equivalent to.
To convert between atoms and moles we use something called Avogadro's constant, which basically acts as the definition of a mole.
More specifically, in order to have one mole of an element you need
6.022 x 10^23 atoms of that element. You can thus use this number as a conversion factor to take you from atoms to moles or vice versa.
In your case, you will have
3.90 x 10^ 26 atoms Zn x 1 mole Zn ( Avogrado’s constant) / 6.022 x 10^23 atoms Zn
= 6.5 x 10^8 is the answer
Answer : The correct answer is, Halide hydrocarbon.
Explanation :
Freon : Freon are the simple aliphatic organic compounds which may contains fluorine, carbon, hydrogen, chlorine or bromine. So, they are a type of chlorofluoro carbons (CFCs).
They are considered as refrigerants which are used in air-conditioning and refrigeration system.
Fluorine will always form an anion. That is because at its basic form, it is electronegative, which means that it attracts electrons who give it a negative charge. This is why it will form an anion.
Explanation:
It is given that the total volume is (10 mL + 60 mL) = 70 mL.
Also, it is known that 
= 
Where, 
= total volume
= initial volume
Therefore, new concentration of 
= 
= 
= 0.43 M
New concentration of NaOH =
= 
= 0.14 M
So, the given reaction will be as follows.
Initial: 0.43 0.14 0
Change: -0.14 -0.14 0.14
Equilibrium: 0.29 0 0.14
As it is known that value of 
= 4.74
Therefore, according to Henderson-Hasselbalch equation calculate the pH as follows.
pH = ![pK_{a} + log \frac{[CH_{3}COO^{-}]}{[CH_{3}COOH]}](https://tex.z-dn.net/?f=pK_%7Ba%7D%20%2B%20log%20%5Cfrac%7B%5BCH_%7B3%7DCOO%5E%7B-%7D%5D%7D%7B%5BCH_%7B3%7DCOOH%5D%7D)
= 
= 4.74 + (-0.316)
= 4.42
Therefore, we can conclude that the pH of given reaction is 4.42.
