Answer:
A
Explanation:
Because it is the greatest
Answer:
the specific shape of letters, e.g. their roundness or sharpness.
regular or irregular spacing between letters.
the slope of the letters.
the rhythmic repetition of the elements or arrhythmia.
the pressure to the paper.
the average size of letters.
the thickness of letters.
Answer:
Explanation:
so u can work out the amount of moles in FeO3 by doing mr of fe3o3 is 55.8*3+16*3=215.4
moles= mass/mr so you do 15.5g/215.4=0.0719 moles
then using 1 to 1 ratio so O2 moles is 0.0719
then use the equation mass=mole*mr
so 0.0719*16=1.15g
hope this make sense :)
Answer:
- <em><u>Mendeleev produced the first orderly arrangement of known elements.</u></em>
- <em><u>Mendeleev used patterns to predict undiscovered elements.</u></em>
Explanation:
- <u>Mendeleev produced the first orderly arrangement of known elements and used patterns to predict the undiscovered elements.</u>
Those two statments are true.
For the time being there were some 62 known elements. Before Medeleev some schemes to order part of the elements were proposed, but Medeleev showed the relationship between the atomic mass and the properties of the elements (supports second choice). This arrangement is known as the periodic table.
More importantly, Mendeleev predicted correctly the existance and properties of unknown elements, which is his major contribution: he left blanket spaces which where gradually filled when new elements where discovered (this supports the fourth choice).
The first modern chemistry book was written by Antoine Lavoisier (this discards first option).
Mendeleev ordered the elements by increasing mass number (this discards third choice), which was corrected later by the scientist Henry Moseley, who ordered the elements by increasing atomic number (number of protons).
Isotopes were not known by Mendeleev times, so this discards the last option.
When an electron absorbs energy, it will move up from a lower energy level to a higher energy level, called the "excited state" of the negatively-charged subatomic particle.<span> However, the absorbed energy is released within a small interval of time and the electron moves down to its "ground state."</span>
