Answer:
Antoine Lavoisier and Johann Wolfang Döbereiner organized the elements based on properties such as how the elements reacts or whether they are solid or liquid.
Explanation:
The periodic table of the elements as we have it today was developed as a result of the work of several notable centuries who lived centuries apart, all of who made notable contributions to development of the modern periodic table in use today.
In 1789, Antoine Lavoisier, a French Chemist provided a definition of elemets which he defined as a substance whose smallest units cannot be broken down into a simpler substance. He further grouped the elements into two as metals and nonmetals.
In 1829, German physicist Johann Wolfang Döbereiner arranged elements in groups of three in increasing order of atomic weight and called them triads. His arrangement owasf elements into triads was based on his observation of similarities in physical and chemical properties of certain elements.
John Newlands, a British Chemist was the first to arrange the elements into a periodic table with increasing order of atomic masses.
In 1869, Russian chemist Dmitri Mendeleev developed a periodic table which provided a framework the modern periodic table. He arranged the elements according to their atomic weight, leaving gaps for elements that were yet to be discovered.
The modern periodic table arranges elements based on increasing atomic number.
Answer: i would say D or the last one.
Explanation: According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants. The law of conservation of mass is useful for a number of calculations and can be used to solve for unknown masses, such the amount of gas consumed or produced during a reaction.
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Answer : The number of iron atoms present in each red blood cell are, 
Explanation :
First we have to calculate the moles of iron.
Now we have to calculate the number of iron atoms.
As, 1 mole of iron contains 
number of iron atoms
So, 0.0519 mole of iron contains 
number of iron atoms
Now we have to calculate the number of iron atoms are present in each red blood cell.
Number of iron atoms are present in each red blood cell = 
Number of iron atoms are present in each red blood cell = 
Number of iron atoms are present in each red blood cell =
Therefore, the number of iron atoms present in each red blood cell are,
