Is C2H4 + 3 O2 → 2 CO2 + 2 H2O a combination

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

7. in the cycle, a virus integrates its dna into the host's dna, and its dna is replicated when the host dna is replicated. a. infectious b. retroviral c. lysogenic d.lytic

Chemistry worksheet - i am not sure what they are asking for exactly?