Use the equations below to calculate the enthalpy of formation for propane gas, C3H8, from its elements, hydrogen gas and solid carbon. Please hurry!! ​

The diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

Which of the following elements would you expect to have the lowest ionization energy value? fluorine, lithium, neon, nitrogen

If 1.8 l of water is added to 2.5l of a 7.0 molarity koh solution, what is the molarity of the new solution