Fuel cells can make an electricity from a simple electrochemical
reaction in which oxygen and hydrogen combine to form water. There are several
different types of fuel cell but they are all based around a central design
which consists of two electrodes, a negative anode and a positive cathode.
These are separated by a solid or liquid electrolyte that carries electrically
charged particles between the two electrodes. A catalyst, such as platinum, is
often used to speed up the reactions at the electrodes. Fuel cells are
classified according to the nature of the electrolyte. Every type needs
particular materials and fuels and is suitable for any applications. The
article below uses the proton exchange membrane fuel cell to illustrate the
science and technology behind the fuel cell concept but the characteristics and
applications of the other main designs are also discussed. Proton Exchange Membrane Fuel Cells (PEMFC)
The hydrogen ions permeate across the electrolyte to the
cathode, while the electrons flow through an external circuit and provide
power. Oxygen, in the form of air, is supplied to the cathode and this combines
with the electrons and the hydrogen ions to produce water. These reactions at
the electrodes are as follows:
Anode: 2H24H+ + 4e-
Cathode: O2 + 4H+ + 4e- 2H2O
Overall: 2H2 + O22H2O + energy
PEM cells operate at a temperature of around 80°C. At this
low temperature the electrochemical reactions would normally occur very slowly
so they are catalysed by a thin layer of platinum on each electrode.
Explanation:
Because people who answer first tend to rush their answers and not do a clear explanation, they often get less recognition than the second person, who usually puts more effort into their answer. The example you gave is an example for that, as the second person has an explanation and more words.
The fruit flys population would be less since the apples isn’t there anymore. The reasoning behind that is because it’s a fruit fly they like being around fruit.
The blood cells likely placed in a "hypotonic solution".
<u>Option: A</u>
<u>Explanation:</u>
When human blood cells are immersed in a solution with a low concentration of solute than is present in cells, osmosis allows water to pass through the cells, allowing the cells to get swollen; such a fluid is hypotonic to the cells. But when held in a solution with a greater concentration of solute, osmosis allows water to pass out of the cell, the cell is smaller and crenated in form; then a solution is hypertonic to the cells.
Healthcare facilities preserve human blood cells in a plasma solution that has the proper salt and protein ratios. Such solution is formulated to be mildly hypertonic to the red cells, thus maintaining the integrity of the cells and avoiding hemolysis.
Answer:
b. giving birth to live young (viviparous)
Explanation:
Monotremes include duck-billed platypus and few other mammalian species that are oviparous. These mammalian species do not give birth to young ones, that is, they are not viviparous. Rather they lay eggs and are oviparous.
These species are also characterized by the absence of teeth. The primitive monotremes also exhibit external fertilization.
Examples of egg-laying mammals include anteaters or echidnas and the duck-billed platypus. The laid eggs are carried by females in an abdominal ouch to keep them warm.
