Answer:
- <em>He realized that some elements had not been discovered.</em>
Explanation:
Some scientists that tried to arrange the list of elements known before Mendeleev include Antoine Lavoisier, Johann Döbereiner, Alexandre Béguyer de Chancourtois, John Newlands, and Julius Lothar Meyer.
<em>Dimitri Mendeleev</em> was so succesful that he is recognized as the most important in such work.
Mendeleev by writing the properties of the elements on cards elaborated by him, and "playing" trying to order them, realized that, some properties regularly (periodically) repeated.
The elements were sorted in increasing atomic weight (which is not the actual order in the periodic table), but when an element did not meet the pattern discovered, he moved it to a position were its properties fitted.
The amazing creativity of Mendeleev led him to leave blanks for what he thought were places that should be occupied by elements yet undiscovered. More amazing is that he was able to predict the properties of some of those elements.
When years after some of the elements were discovered, the genius of Mendeleev was proven because the "new" elements had the properties predicted by him.
A gauge records the pressure over atmospheric pressure (0kpa on the gauge is actually the atmospheric pressure and a reading of 276kpa is 276kpa over atmospheric pressure). That means that means that to find absolute pressure you just add atmospheric pressure (around 1atm (101kpa)) to 286kpa to get 387kpa. I hope this helps.
Answer:
The 3rd option is correct
Explanation:
The element in group 13 and period 3 is aluminium which has the electron configuration

or [Ne] 3s^2 3p^1
Answer:
An Acid Test
An acid test is any qualitative chemical or metallurgical assay which uses acid ( most commonly), and historically, the use of a strong acid to distinguish gold from base metals.
Explanation:
I hope it helps
Answer:
5.85 g C2H6O has more carbon
Explanation:
Weight of carbon in 4.71 g of C6H12O6
grams
Weight of carbon in 5.85 g of C2H6O
grams
Hence, 5.85 g C2H6O has more carbon