Tijuan mixed a solid and a liquid together in a beaker. He determined that a chemical change occurred. If his conclusion is correct, which substances could he have been observing and why?

ice mixed into warm oil, because the change of state that occurred when the ice melted cannot be reversed
baking soda mixed into vinegar, because the production of bubbles indicates that a new substance formed
sugar mixed into hot water, because the disappearance of solid indicates that the chemical identity of the sugar changed
sand mixed into water, because when sand was added the mass of the beaker increased

The last few miles of the marathon are the most difficult for heather, her hair plastered to her head, sweat clinging to her arms, and her legs already feeling as if they had nothing left, just dead weight. after grabbing a cup of ice water, she feels the ice cubes smash against her nose as she gulps some cool refreshment and keeps on running. in these last few miles, the breeze kicks up and she finally feels some coolness against her skin. drips of sweat, once clinging to her forehead, now spill down, and heather feels more pain as the sweat flows into her eyes.which of the following is the most likely reason why the ice struck heather’s nose when she took a drink? a) water can function as a solvent. b) water can store large amounts of heat. c) water can moderate temperatures through evaporative cooling. d) the density of water decreases when it freezes. e) water has a cohesive nature.sweat remained on heather’s forehead and arms because of the a) high salt content of sweat b) cohesive nature of water c) ability of water to moderate heat d) high evaporative cooling effect of water e) ability of water to act as a solvent

F1.5 mol of nabh4 react, how many moles of b2h6 are formed? 2 nabh4(aq) + h2so4(aq) → 2 h2(g) + na2so4(aq) + b2h6(g)

Which statement is true according to the kinetic theory? a. molecules of different gases with the same mass and temperature always have the same average density. b. molecules of different gases with the same mass and temperature always have the same average volume. c. molecules of different gases with the same mass and temperature always have the same pressure. d. molecules of different gases with the same mass and temperature always have the same molecular mass. e. molecules of different gases with the same mass and temperature always have the same average kinetic energy.