Answer:
The natural phenomenon used to describe the length of a meter is the speed of light. The length of a meter is the length a light path travels in 1/(299792458) seconds through a vacuum.
The definition is better due to the uncertainty involved in the use of the length of a standard meter stick because the length of the meter stick could change due to atmospheric conditions from place to place
Explanation:
The correct answer is B) they operate at a higher efficiency. sorry hope the answers not to late :(
One mole of any element is Avogadro's number, which is 6.02 * 10^23 atoms.
One mole of Calcium is equal to its atomic weight in grams, 1 mole Ca = 40.08 x 1000 mg = 6.02 * 10^23 atoms.
We have 8.6mg of Ca which means 8.6mg / 40,080mg = .00021457 of a mole of calcium.
Now multiply that by Avogadro's number which gives number of atoms = 0.00021457 * 6.02 * 10^23 atoms. So the answer is 1.292 * 10^20 atoms of Ca.
Answer:
(a) ₁₉K: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
(b) ₁₀Ne: 1s² 2s² 2p⁶
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(a) 3
(b) 6
(c) 7
Explanation:
We can state the ground-state electron configuration for each element following Aufbau's principle.
(a) ₁₉K: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
(b) ₁₀Ne: 1s² 2s² 2p⁶
Second part
(a) Al belongs to Group 13 in the Periodic Table. It has 13-10=3 electrons in the valence shell.
(b) O belongs to Group 16 in the Periodic Table. It has 16-10=6 electrons in the valence shell.
(c) F belongs to Group 17 in the Periodic Table. It has 17-10=7 electrons in the valence shell.
Answer: Option (d) is the correct answer.
Explanation:
It is known that polyethene which have high density and these are generally safe plastics which does not transfer any chemicals to food ingredients. In most of the industries, these type of plastics have large application because these can be used to prepare plant pots, plastic woods, furniture etc.
High density polyethene is also known by the short form HDPE.
Whereas low density polyethene (LDPE), PVC, polystyrene and polypropylene are not safe plastics and they tend to harm the environment. So, they are not safe to store or preserve food items.
Thus, we can conclude that out of the given options HDPE polymers is used in plastic bottles and plastic containers.