<h3><u>
The following events are identified as chemical weathering:</u></h3>
- The minerals in a marble statue react with water to form acids and pores in the structure.
- The rocks in a region are streaked orange after being exposed to repeated rains.
<em><u>Reason: </u></em>
When the weathering process occurs due to <em>chemical reaction</em>, then it is considered as chemical weathering. 
In <em>the first case</em>, minerals of marble statue are <em>reacting</em> with water to cause weathering. In the <em>second case</em>, due to the <em>acidificaion reaction</em>, the change of the color has happened after exposure to the repeated rains.
<h3><u>
The following events are identified as Mechanical weathering:</u></h3>
- A piece of rock crumbles after being constantly thrashed by strong waves.
- Industrial runoff forms cracks in a rocky structure in its path.
<em><u>Reason:</u></em>
When the rock is broken into simple pieces <em>without any chemical reaction </em>it is considered as mechanical weathering. 
In the <em>first cause</em>, due to the <em>abrasion</em> caused by the strong waves, weathering has happened, in the <em>second case</em> industrial run off may be of varying temperature and thus may cause <em>heating or cooling</em> of the rock and causes weathering.
 
        
             
        
        
        
Porosity
Porosity refers to the space inside the rock that is taken up by pore space.
        
             
        
        
        
Translation proceeds in three phases: Initiation: The ribosome assembles around the target mRNA. The first tRNA is attached at the start codon. Elongation: The tRNA transfers an amino acid to the tRNA corresponding to the next codon.