Answer:
The correct answer is C. element
Explanation:
The sample cannot be an element because an element - or <em>elemental substance</em> - cannot be decomposed into simpler substances. Thus, it cannot be composed by differents types of atoms. For example, an element is carbon (C).
As the sample contains <u>three types of atoms</u>, it can be a compound, a molecule or a mixture, because they can be composed by different types of atoms - of different chemical elements. For example, the sample could contain the element carbon (C) combined with other elements, for example oxygen (O) or hydrogen (H), amoing others.
Answer:
13.5 years
Explanation:
Initial Concentration [Ao] = 10g
Final Concentration [A] = 0.768g
Time t= 50 years
Half life t1/2 = ?
These quantities are related by the following equations;
ln[A] = ln[Ao] - kt ......(i)
t1/2 = ln(2) / k ...........(ii)
where k = rate constant
Inserting the values in eqn (i) and solving for k, we have;
ln(0.768) = ln(10) - k (50)
-0.2640 = 2.3026 - 50k
50k = 2.3026 + 0.2640
k = 2.5666 / 50 = 0.051332
Insert the value of k in eqn (ii);
t1/2 = ln(2) / k
t1/2 = 0.693 / 0.051332 = 13.5 years
Cotton a thin membrane like skin dye and a liquid that helps absorb things
Answer:
O A. A metal higher on the activity series list will replace one that is
lower.
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.
