Answer:
Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance to change into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions.
Explanation:
Nickel is the 28th chemical in the periodic table and the chemical symbol of copper (II) nitrate is Cu(NO₃)₂. The chemical reaction that occurs between these compounds is a single-replacement reaction.
From the activity series of metals, nickel is able to replace copper in the compound and this is expressed in the balanced equation,
Ni(s) + Cu(NO₃)₂(aq) --> Cu(s) + Ni(NO₃)₂(aq)
The phases are also written in the equation.
Answer : The boron-11 isotope is the most abundant.
Explanation :
As we are given that:
Average atomic mass of boron = 10.81 amu
Mass of boron-10 = 10.0129 amu
Mass of boron-11 = 11.0093 amu
As we know that the average atomic mass of an element is always closest to the most abundant isotope.
Out of the two boron isotopes, B-11 is closest in mass to the weighted average. Therefore, it is the most abundant.
Hence, the boron-11 isotope is the most abundant.
I believe that the delta h formation or enthalpy of
formation is only zero for pure elements. They are zero because they are the
most basic substances, that is you cannot form an element from an element.
Since Ozone is already a compound, a mixture of 2 oxygen O2 atoms, therefore
the δh∘<span>f is
not necessarily zero.</span>
In the given chemical reaction iron is less electropositive metal and aluminum is more electropositive and behave as a reducing agent also.
<h3>What is electropositivity?</h3>
Electropositivity is the ability of an atom of donation or losing of electrons easily.
From the given chemical reaction it is clear that oxidation state of iron changes from +3 to 0 & of aluminum is from 0 to +3. So in the above chemical reaction aluminum is more electropositive than iron metal. And aluminum is behave as a reducing agent as it helps in the reduction process by providing electrons.
Hence aluminum is electropositive metal and reducing agent, iron is less electropositive.
To know more about electropositivity, visit the below link:
brainly.com/question/21819287
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