The correct answer is D:
it involves breaking molecular bonds between copper compounds
.
The explanation :
-when we melt a copper it is a physical change because the substance is still copper and have the same shape.
- but for example Burning a copper it is a chemical change. Fire activates a chemical reaction between copper and oxygen.
-The oxygen in the air reacts with the copper and the chemical bonds are broken.
- the chemical change is changing the other compound bonded to the copper atoms.
So, the correct answer is D
2Pb(NO₃)₂ = 2PbO + 4NO₂ + O₂
m{Pb(NO₃)₂}=9.9 g
m'{PbO}=5.5 g
M{Pb(NO₃)₂}=331.2 g/mol
M{PbO}=223.2 g/mol
w-?
w=m'{PbO}/m{PbO}
m{PbO}=M{PbO}m{Pb(NO₃)₂}/M{Pb(NO₃)₂}
w=m'{PbO}M{Pb(NO₃)₂}/[M{PbO}m{Pb(NO₃)₂}]
w=5.5*331.2/[223.2*9.9]=0.8244 (82.44%)
Explanation:
Alkali metal cations reacts vigorously with halogens to form ionic/electrovalent compounds.
- The alkali metals are about the most reactive metals and they belong to group I .
- In their outermost shell, they have one valence shell electron.
- Alkali metals are largely electropositive willing to release their valence electron to attain stability.
- The halogens have seven electrons in their outermost shell. To complete their configuration, they need just one electron.
- All the halogens are strongly electronegative and they are readily reactive.
- In the vicinity of group 1 elements, they react vigorously.
- This is due to the electrostatic attraction between the metal and non-metal ion formed.
- Therefore, they form strong ionic bonds between their compounds.
Learn more:
sodium alkali and halogens brainly.com/question/6324347
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