Scientists believe that our galaxy, the Milky Way, is home to millions of black holes. Only 60 of them have been officially detected. The correct answer is B. The largest known type of black hole is termed as a supermassive black hole and is located in the center of each galaxy. In the Milky Way, this is called Sagittarius A*.
Answer:
External factors include physical and chemical signals. Growth factors are proteins that stimulate cell division. – Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.
Explanation:
From Google
The periodic chart was first arranged by atomic mass by Dmitri Mendeleev. By grouping the columns into groups, Henry Moseley later refined the periodic table's layout. Thus, the correct option is D.
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What is periodic table?</h3>
The periodic table is a tabular collection of chemical elements arranged according to atomic number, starting with hydrogen and going up to oganesson, which has the highest atomic number. The quantity of protons in the nucleus of an element's atom is known as the element's atomic number.
Mendeleev set up the periodic table by the atomic mass, also leaving spaces blank for elements that had not yet been discovered. Many elements that Mendeleev put on his periodic table are the same elements.
The last piece of the puzzle came together six years after Mendeleev's passing. The atomic mass used to arrange the periodic table almost always yields the same order as the atomic number. There were a few exceptions, though, that didn't work (like iodine and tellurium, as mentioned above). Mendeleev had recognized that they needed to be switched around, but Moseley was the one who made the decisive discovery.
For more information regarding Mendeleev, visit:
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Remember that sodium channels are necessary for action potentials to take place. When a neuron receives a signal from a presynaptic cell, the membrane on the postsynaptic cell depolarized slightly. When this occurs, if the membrane reaches a certain threshold, voltage-gated sodium channels will open, allowing sodium ions to rush into the neuron. If these channels were non-functional, the neuron would be unable to depolarize, therefore inhibiting its ability to produce an action potential. This would keep the neuron from communicating with other cells. I hope this helps you!
