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.
Answer:
The cat
Explanation:
1) You need to find how many meters per second each thing is sprinting, so you can divide the meters by seconds for each.
2) Per second, the sprinter is able to achieve 8 meters, while the cat can do around 10.5 meters. 10.5 is greater than 8, making the cat faster than the sprinter.
is the Lewis base in the following reaction:
→
<h3>What is lewis base? </h3>
Lewis base is a species that donates an electron pair.
In the above-given chemical equation, the is the lewis base which is donating an electron pair to the central atom of to form .
Hence, is the Lewis base in the following reaction:
→
Learn more about the lewis base here:
brainly.com/question/15570523
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Answer:
E. a small yellow ball that represents the Sun
Explanation:
key word on the question, 'physical'
Place the mixture in hot water and stir well.
<span>The KNO3 is very soluble in hot water. </span>
<span>Use a fine filter paper and filter off the sand. </span>
<span>The sand will be separated from the KNO3 solution. </span>
<span>The water can now be evaporated from the solution by further, gentle heating leaving the solid in the container.</span>