When energy is needed in order for the reaction to happen, then that reaction is known as endotermic. When the reaction has as a result energy then it is exotermic. An example of an endotermic reaction would be photosynthesis, for an exotermic: combustion.
The freezing point would be 3.72 *C
O = C = O Straight because there is no solitary electrons on C
Chemical properties of matter can only be observed and measured by performing a chemical change.
- Density and boiling are not chemical changes.
- This leaves reactivity and combustion. Reactivity does not need to be observed at STP so the statement is wrong.
Combustion is the best answer.
They have seven electrons in their valence shell, so halogens are very reactive.
Hope this helps! :)
