Answer:
Scandium
Explanation:
Mendeleev played an important role in the development of the modern periodic table. His periodic table was filled with gaps. He said that these gaps were elements that were yet to be discovered. He rightly predicted many elements which have now been discovered and fitted in their proper places in the periodic table.
He used the prefix ''eka'' to refer to elements whose properties were alike but were yet to be discovered at that time.
The compound named ekaboron which he predicted to have an atomic weight between 65 (zinc) and 75 (arsenic) with a valence similar to aluminum was later discovered in 1879 and properly named scandium.
- The molar mass of 0.458-gram sample of gas having a volume of 1.20 l at 287 k and 0.980 atm is 9.15g/mol.
- If this sample was placed under extreme pressure, the volume of the sample will decrease.
<h3>How to calculate molar mass?</h3>
The molar mass of a substance can be calculated by first calculating the number of moles using ideal gas law equation:
PV = nRT
Where;
- P = pressure
- V = volume
- T = temperature
- R = gas law constant
- n = no of moles
0.98 × 1.2 = n × 0.0821 × 287
1.18 = 23.56n
n = 1.18/23.56
n = 0.05moles
mole = mass/molar mass
0.05 = 0.458/mm
molar mass = 0.458/0.05
molar mass = 9.15g/mol
- Therefore, the molar mass of 0.458-gram sample of gas having a volume of 1.20 l at 287 k and 0.980 atm is 9.15g/mol
- If this sample was placed under extreme pressure, the volume of the sample will decrease.
Learn more about gas law at: brainly.com/question/12667831
I believe the answer is a because 2 times 12 is 24. Hope this helped
The answer is 7. Valence electrons are the electrons in the very last shell, so we need to look at the outer “circle” and count the electrons, or the little black dots. There are 7 in the last shell.
Chlorine gas reacts to potassium bromide to form potassium chloride in solution and liquid bromine.
I hope this helps/answers your question! I vaguely remember getting this question before too
