This seems like an incomplete question..
Mechanical digestion is chewing, and chemical digestion is the saliva in your mouth breaking down food.
Its because the molecules in the solid structures are very close to each other and rigidly packed, thus due to this quantum structure they have pretty awesome speed of sound in them
<h3><u>Answer and explanation;</u></h3>
-Rate of reaction is the speed at which the reactants are converted to products.
-Rate of reactions depends on a number of factors which includes<u>;</u>
- <em><u>Concentration of reactants</u></em>;<u><em> increasing the concentration of reactants</em></u> increases the rate of reaction.
- <u><em>Temperature;</em></u><u><em> </em></u>An <u><em>increase in temperature results to an increased rate of reaction.</em></u> Increase in temperature increases the kinetic energy of molecules thus the collision per unit time also increases and hence the rate of reaction increases.
- <u><em>Decreasing the size of particles of solid reactants</em></u> also increases the rate of reaction. This is because smaller particles increases the surface area on which more collisions can occur thus a faster rate of reaction.
- <em>Adding a catalyst also increases the rate of reaction.</em> This is because catalysts lower the activation energy of reactants, minimum energy require by reactants for the reaction to take place. This thus increases the rate of reaction.
Which is a drawback of solar energy?
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A. It depends on the climate.
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B. It is not a renewable resource.
C. It is difficult to use for electricity.
D. It can be a source of water pollution.