Answer:
Option A. a chemical change
Explanation:
A chemical change is a change in which new substance is formed and can not be easily reversed. A change of metal color when exposed to air for a long time is simply called rusting. This is a chemical change as new substance is formed. This can be seen when Zn roofing sheets changes color over time on exposure to air.
Answer:
i know the answer but i dont have time bro
Answer:
45) the answer is C.
46) The calculation of quantities in chemical reaction is called Stoichiometry
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47) The phase changed from solid to gas so I think the answer is A.
48) The phase changed from solid to gas as well so I think that the answer is A again.
49) Applying the formula n = m/M, we have n = 1.5 moles, therefore the answer is D.
50) C2H4 + 3O2 -> 2H2O + 2CO2
The answer is C.
51) The answer is C.
52) 2NaHCO3 + CaCl2 -> CaCO3 + H2O + 2NaCl + CO2
Hopefully I got all of them correct.
The mass number can vary without changing the identity of an atom whereas change in atomic number may not be possible.
Atomic number of an atom is the number of protons or electrons in an atom. So the atomic number is an essential criteria for the identification of an element. No two elements will have the same atomic number. Thus atomic number cannot be changed for a particular atom. This is because the number of protons cannot be changed.
Mass number is the sum of the number of protons and neutrons of an atom. This can be varied without changing the identity of atom. We call them isotopes. Some elements have more than one kind of atoms with different mass number but same atomic number. For example, Hydrogen has three isotopes. These are formed by the difference in the number of neutrons in an atom.
Learn more about Atomic and Mass number at brainly.com/question/338808
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match of the unkwown ions to its appropriate description is as below
A-A)= A non metal that gained one electron.
B+B) = A metal that lost one electron
C2-C) = A non ,metal that gained two electrons
D2+D)= A metal that lost two electrons.
<u><em>Explanation</em></u>
<u> </u> Metal - form a positively charged ion by losing valence electrons ( electron in the outermost energy level).
For example Metal D loses 2 electrons to form D2+ ion.
Non metal form a negatively charged ion by gaining one or more electrons in order to fill it's valence shell .
For example non metal A gain 1 electron to form A- ion.