The catalyst (4) decreases the activation energy required for a reaction, by holding reactants in place
Because during combustion reaction, heat energy is released and it's this energy that is converted to work
<span>A covalent bond is a bond formed by atom sharing.
In water molecule, there are twice the number of hydrogen atoms than the oxygen atoms. Its structure is H-O-H. The electronegative difference between the H and O allows them to be polar because on side there is positive charge and on another side there is negative charge.</span>
Well the organism that is producing an offspring is already very adapted to it's surroundings. So, the organism has developed characteristics that help it survive in it's environment. These traits are passed down to the offspring. Creating adaptations to this particular species.