Answer:
Isotopes of an element have same number of protons but different number of neutrons. Which means isotopes of an element have same atomic number but different mass number.
The chemical property of an element is determined by the number of electrons. And as all the isotopes have same number of electrons, they have same chemical properties.
Thus as isotopes of an element have same atomic number , they have same number of electrons and protons. As they have different mass number, the number of neutrons will be different. Hydrogen has three isotopes , 
, 
and 
. Thus has no neutron.
One way they are different is that they show elevation
Answer:
Explanation:
exothermic reactions are the reactions which involve the release of energy.
the energy released can be of any forms ,for example heat,light .
all the combustion reactions are exothermic reactions
Analyzing a biomolecule X, a scientist verifies that it is made up of Carbon, Hydrogen, Oxygen and Nitrogen, in addition to releasing water when it joins with other similar molecules to form polymers. Considering these antecedents, it can be inferred that biomolecule X corresponds to: A Steroids B fatty acid C nucleotide D amino acid E monosaccharide (for people who dont speak spanish)
ok you answer is probably A
if wrong C maybe
~hope~
Answer:
1. Dmitri Mendeleev
2. Johann Dobhereiner
3. John Newlands
4. Henry Moseley
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