Which of the following is an example of a decomposition reaction? numbers in parenthesis are subscripts
1. 2cr + 3cl(2) yields 2crcl(3)
2.cro3 yields cr(2)o(3) + o(2)
3. ca + 2h(2)o yields ca(oh)(2) + h(2)
4. 2hcl + ca(oh)(2) yields cacl(2) + 2h(2)o

Achemistry student weighs out of phosphoric acid , a triprotic acid, into a volumetric flask and dilutes to the mark with distilled water. he plans to titrate the acid with solution. calculate the volume of solution the student will need to add to reach the final equivalence point. round your answer to significant digits.

The enthalpy of formation of water is -285.8 kj/mol. what can be inferred from this statement?

Compare and contrast physical changes with chemical changes.