In late 18th century, people wore rubber soled shoes called plimsolls, but they weren't the best sneakers. Around 1892, a US company named Keds started sneakers with a canvas top and rubber soles. By 1917, these were mass produced.
Ans: As changes in energy levels of electrons increase, the frequencies of atomic line spectra they emit will <u>increase.</u>
The energy (E) is related to the frequency (ν) by the following equation:
E = hν
where h = planck's constant
The change in energy i between levels is:
ΔΕ = h(Δν) -----(1)
Based on the above equation, as the changes in energy levels increase, the frequency of emitted radiation will also increase.
It is important to take note of th temperature in determining the density of a substance because this will set as a basis and will likely be a variable in the experiment because this will also contribute on the effects of the experiment and a basis of how the experiment has turned to be that way.
Answer: Hope this helps
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Explanation: <u><em>
The fertilized egg zygote divides repeatedly as it moves down the fallopian tube to the uterus. First, the zygote becomes a solid ball of cells. ... Inside the uterus, the blastocyst implants in the wall of the uterus, where it develops into an embryo attached to a placenta and surrounded by fluid-filled membranes.</em></u></h3><h3><u><em /></u></h3>
Answer: BF3
Explanation: boron needs 4 electron to obtain octet and Fluorine has just one. For the valence shell to be completely filled it will have to form BF4- with 4 fluorine atom surrounding it.
