Is it necessary to conserve energy if we are using biofuel ?instead of diesal

yes

Explanation:bio fuel is environment friendly and also would conserve the environment from pollution and destruction in the obtainance of petroleum

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

b) nuclear ive learned that in a pedtrodic table