I need help on deciding which one i should get

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

Fill in the blanks for the following statements: the rms speed of the molecules in a sample of h2 gas at 300 k will be times larger than the rms speed of o2 molecules at the same temperature, and the ratio µrms (h2) / µrms (o2) with increasing temperature. a not enough information is given to answer this question b sixteen, will not change c four, will not change d four, will increase e sixteen, will decrease

Which of the following is an example of a crystalline solid