If you do not perceive a color change, or the emission of light or heat, it is still possible a chemical reaction has taken place.
A chemical change involves a change in the composition of a substance. It leads to the rearrangement of atoms and formation of a new substance.
Some cues may help us to know when a chemical change has taken place such as;
- Change in color
- Formation of a solid
- Evolution of heat
- Evolution of a gas
It is possible for a chemical change to occur without noticing these cues. For instance, two colorless solutions may react with each other and the product of the reaction remains colorless.
In this case, there is no physical cue signifying that a chemical change has taken place even though it actually happened.
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Humans and animals need oxygen to survive so oxygen in the atmosphere maintains life on earth for humans and animals to breathe to survive
Cells can repair themselves in a molecular level through its DNA and the process involve, either the old damage cells are renewed and resynthesized by new ones as cell divides and undergoes such division.
<span><span>Organelles
are tiny parts of a cell, in analogy are like organs. They perform
various tasks vital for a cell to survive. They deliver information,
send nutrients and excrete waste and protect cells from antibodies and
other microorganisms that could and possible harm the cell itself.<span> </span></span>
Cells repair themselves through the process of cell division and mitotic process. <span>Mitosis
occurs more in your body since it changes, modifies and requires cell
division at maximum rate in many useful situations with the stand to a
particular system and organ. Mitosis and meiosis are simply cell
division processes that occurs differently, they're characteristically
divergent from each other according to their function and structure.<span>
</span></span></span>
B. alternating phosphate groups and pentose residues
