Answer:
- <em><u>A. isotopes </u></em>
<em><u></u></em>
Explanation:
The <em>periodic table</em> was organized by Dimitry Mendeleiev by 1869, as he showed the connection between the atomic mass and the properties of the elements.
Nevertheless, the order of some few elements had to be altered because the properties did not follow the order of the atomic masses.
Henry Mosely by 1913 determined that atoms of a same element had different number of neutrons, leading to different atomic masses. These atoms of a same element (with the same number of protons) with different number of neutrons are known as<em> isotopes.</em>
By arranging the elements in increasing order of the number or protons (atomic number), instead of the atomic masses, all the elements resulted ordered according with a repetitive (periodic) pattern of chemical properties.
Answer:
K8S4O16 or K8(SO4)4 depending on if the SO4 is supposed to represent sulfate or not
Explanation:
Find the molar mass of K2SO4 first:
2K + S + 4O ≈ 174 g/mol
Divide the goal molar mass of 696 by the molar mass of the empirical formula:
696 / 174 = 4
This means you need to multiply everything in the empirical formula by 4:
K2SO4 --> K8S4O16 or K8(SO4)4 depending on if the SO4 is for sulfate or not
Answer: 20 mg Te-99 remains after 12 hours.
Explanation: N(t) = N(0)*(1/2)^(t/t1/2)
N(t) = (80 mg)*(0.5)^(12/6)
N(t) = 20 mg remains after 12 hours
Answer:
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