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.
B- is the answer
Hope this helps
Have a nice day~
Answer: 318 K
Explanation:
Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.
The combined gas equation is,
where,
= initial pressure of gas = 231 kPa
= final pressure of gas = 168 kPa
= initial volume of gas = 3.25 L
= final volume of gas = 4.35 L
= initial temperature of gas = 
= final temperature of gas = ?
Now put all the given values in the above equation, we get:
At 318 K of temperature will the same gas take up 4.35 liters of space and have a pressure of 168 kPa
