A group of 500 people are selected at age 2 no0 and followed for 15 years. The people who go on to develop a certain type of cancer are compared those who do not. The researchers attempted to determine different factors that could increase cancer risk

Use the standard enthalpies of formation for the reactants and products to solve for the δhrxn for the following reaction. (the δhf of c2h4 is 52.26 kj/mol, co2 is -393.509 kj/mol, and h2o is -241.818 kj.) c2h4 (g) + 3o2(g) 2co2 (g) + 2h2o(g) δhrxn = the reaction is .

The answer for #3 is c but i don't know why

Idon't really understand this can you me and show your work.☺☺[ chemistry b] subject [ electron transfer in lonic bonds]grade( 12)