Answer:
Both <u>elements </u>and <u>compounds</u> can be classifies as pure substances because they have distinct properties and composition.
Explanation:
Elements and compounds are considered as pure substances because both are always formed form are have same kind of atoms.
For example,
Carbon dioxide is compound. It always consist of one carbon atom and two oxygen atoms.
Water is compound it always have same kind of atoms two hydrogen and one oxygen that's why compounds are considered as pure substances.
Same is the case with elements. For example,
Hydrogen is element and it always consist of H atoms.
Iron is another element and it always have iron atoms.
So elements and compounds are always consist of same substances that's why they are considered as pure.
"Endothermic" is the way among the following choices given that you would <span>classify the following chemical reaction, in terms of energy. The correct option among all the options that are given in the question is the second option or option "B". I hope that the answer has come to your help.</span>
Answer:
d. 127 g/mol.
Explanation:
Hello!
In this case, since we have the amount of molecules of this this compound, we are able to compute the moles out there by using the Avogadro's number:

Which correspond to the moles of X2. Then, by using the mass we are able to compute the molar mass of X2:

It means that the atomic mass of X halves the molar mass of X2, which is then d. 127 g/mol.
Best regards!
Explanation:
The similarities between chemical and physical changes include change in state of matter and both process involve change in energy.
Chemical changes of a substance results in the formation of entirely new substances. These changes are not reversible.
Physical changes results in the change of the state of the substance which can be reversed.
However, both chemical and physical changes results in change of state of matter and both process results in change in energy.
Thus, we can conclude that the similarities between chemical and physical changes include change in state of matter and both process involve change in energy.
(it's alre answered but here it again 'NOTE: not my answer')