Answer:
a. positive
b. negative
c. positive
d. negative
Explanation:
In a exothermic reaction, heat is written as a product (del H is negative), whereas in an endothermic reaction heat is written on the reaction side (del H is positive).
For a, it is endothermic process. We know this because to go from solid to liquid you need to put energy into the system. When we put energy into a chemical system it is said to be an endothermic reaction.
For b, it is exothermic reaction. This is because you have to lose the extra energy to go from less ordered states (gas) to more ordered state (liquid). Gas is less ordered because its molecules are freely moving and such. Another way of thinking about this question is just putting the heat on product side and think if I was going in reverse direction I would put heat in product because I would need to add heat to liquid to turn to gas (and if heat is added to product side we know its exothermic). Two ways of thinking whichever you prefer.
The rest have similar explaination.
Answer:
This question is hard :( I dont know im so sorry
Explanation:
I have written it out and explained it. I hope it helps! Here:
Answer:
There is no chemical symbol for paper since it is not an element but rather a mixture of several different compounds. Mixtures in two or more phases are heterogeneous mixtures.
Explanation:
She has the sea (water), the sand could be viewed as the geosphere and clearly the biosphere. I think for the environment to apply here I would hope to see something about it in the analysis.
Truly, I could go whichever way on this one.
<span>Observe how the sand and plants are displaced by the waves.</span>
