Answer: The correct option is A.
Explanation: In a chemical reaction, reactants react to form a number of products.
For the formation of products, the bonds of the individual reactants must be broken and the bonds of the products must be formed.
For example: Formation of water from hydrogen gas and oxygen gas. Reaction follows:

The Bonds of hydrogen and oxygen molecule are broken and new bonds between hydrogen and oxygen atoms are formed to give water molecule.
Answer:
it is also know as biological diversity
Explanation:
it refers to the varieties or various forms of plants and animals species
Answer:
The electrons are supplied by the species getting oxidized. They move from anode to the cathode in the external circuit. The external battery supplies the electrons. They enter through the cathode and come out through the anode
Answer:
24m/s
Explanation:
a=change of v/change of t
6m/s^2=v/4s
multiply both sides by 4s
v=24m/s