Physics questions help plz whoever gives me the correct answer and explains gets the 10 points thanks?

Question

Which of the following indicates that a reaction is endothermic?
a. The products of the reaction include gases
b. The reactants are in either solid or liquid form.
c. The products of the reaction include light and heat.
d. The reactants must be heated for the reaction to occur.

The primary way that an iron rod held in a flame absorbs heat is through
a. conduction
b. reflection
c. radiation
d.convection

Green plants turn light into energy from the sun into:
a. thermal energy
b. kinetic energy
c. gravational potential energy
d. chemical energy

Answer 1

1. D; endothermic... "endo" pretty much means "inside" and thermic, like thermal, relates to temperature particularly with heat. So we know that it has to do with temperature and thus can eliminate A and B; there is a possibility that A and B can be right as well, (for instance, ice melting is an endothermic reaction but produces liquid and could also produce a gas) but I'm assuming your looking for the best possible answer. We also derive from the word endothermic that whatever reaction we are considering is occurring "within" something. Going with our ice example we could also eliminate C, with our current understanding of our physical world one would be on the higher echelon of genius if they figured out a way that one correct. Ice converted into light... even better pure energy? The implications are rad, if not seemingly impossible. E = mc^2 is energy = matter x constant speed of light squared... I'm digressing. Just pick D.

2. A ; well it's not reflection, because that means heat is being lost from the system (iron rod and flame) into something else. When one thinks of convection, one thinks of "convection currents" which is how liquids transmit their heat/energy and some gases. Radiation, maybe, would depend on the system to determine propagation... but it's doubtful that's what the question is looking for. Only one left is conduction. I don't really know how to break the word "conduction" down further, it seems rather obvious what it means to me... but I suppose you can think of it like the word "conducive" (which may not help anymore then conduction). Um, something flowing through something else; the essence of conduction. Like water through a straw... but in this case, heat through iron for the iron rod is conductive.
3. D; lol, I don't even want to try and explain the other ones in layman's terms... but just remember that most plant life receive energy through a process called photosynthesis. "photo" in relation to "light" and synthesis to say it is synthesized. Light is synthesized into energy for the plant. This is a chemical process.

I could explain these examples more scientifically if you'd like, for I feel I can do such much more proficiently. But I'm assuming you didn't need convoluted responses, and being that I'm studying undergraduate level theoretical physics I have to try my hand at explaining things in a simple manner one day or another.

Answer 2

An endothermic reaction will feel cold to the touch because it is taking in the heat from your hand. Answers a. and b. describe many kinds of reactions. I say the answer is d since heat is absorbed.

If the iron rod is held in the heat then the heat is transferred by conduction. That is the direct contact of molecule to molecule. Solids are generally not heated by convection since convection requires the moving of molecules from one place to another. (liquids and gases)

Green plants change light into chemical energy. Glucose is the stored chemical energy.

Answer 3

D - "endothermic" describes a process or reaction that absorbs energy in the form of heat. If a reaction is endothermic, it must absorb heat in order for it to occur. Hence you must heat the reactants.

A - a flame is hot gas. Physical contact between the hot gases and the iron rod is responsible for most of the heat transfer. Radiation (electromagnetic radiation in the form of infrared and visible light) from the hot gas molecules to the iron rod is secondary.

D - Chlorophyll in plants absorb energy from photons and via a complicated chemical cascade, stores it as ATP, then as sugar, and then as starch. All of these count as chemical energy carriers.

Answer 4

Second question
- a (much in the way that rubber conducts electricity)
Third
-d (It's not any of the others. And it turns it into food for the plant.)

Answer 5

cad endo=inside therm=heat .metal conducts heat.photosynthesis is a chemical reaction

Answer 6

C, A (assuming flame touches rod. if the air heated heats the rod, then it would be...convection. if it refers to the heat going through the air toward the rod (USUALLY　ＤＯＥＳ　ＲＥＦＥＲ　ＴＯ　ＴＨＡＴ　ＷＡＹ）ＴＨＥＮ　ＩＴ　ＷＯＵＬＤ　ＢＥ　ＲＡＤＩＡＴＩＯＮ）．ＬＡＳＴ　ＯＮＥ　ＩＳ　Ａ

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Answer 7

1) no ideal
2) not sure.. a or d i think d
3) D it turns it into glucose

Answer 8

c
a
d

Answer 9

1)d
2)a
3)a