Which of the following conditions is closely related to a chemical reaction? urgent, kneeling and b

There are the following facts:1Gently rub two pieces of paper of the same size into a paper ball, take another one and fold it in half 4 6 times, and press it into a piece of paper, and light it separately with a match, it can be seen that the paper ball burns vigorously, and the paper piece does not burn vigorously.

From the point of view of the degree of contact with oxygen, there is obviously a gap in the middle of the paper ball, which is easy for oxygen (air) to diffuse to the surface of the paper, while the pressed paper cannot be in good contact with oxygen. It shows that the chemical reaction is related to the size of the surface area of the substance.

2.Cooking oil at home, pour some in a small spoon and light it with a match, it is not easy to burn. And stir-fry is often abrupt**.

Combustion is related to the ignition point of the substance, and the temperature of the match is not as high as the temperature of the pot. Chemical reactions are affected by their own properties.

3.Food is not perishable easily in the winter and spoils easily in the summer.

Deterioration is usually the chemical decomposition of microorganisms, and microorganisms multiply quickly in the summer when the temperature is higher, so the food is more perishable, of course, the higher the better, and the microorganisms will also be killed if the temperature is too high. And low temperatures are the opposite. So the ambient temperature also has an effect on the chemical reaction.

4. According to the amount of alcohol content, liquor is divided into high alcohol and low alcohol alcohol, and 70° high alcohol is easy to ignite. And the 30° one is not easy to ignite.

Based on the above facts, let's talk about the chemical reaction and the external conditions.

The higher the temperature of the reaction system and the greater the concentration of reactants, the easier the reaction is carried out and the faster the reaction rate.

There are no specific conditions for chemical reactions, but there is only one product.

Decomposition reaction, there are no specific conditions, but there is only one reactant.

Metathesis reaction, the condition is to generate a substance that is difficult to ionize, not necessarily in solution (such as NaOH + NaHCO3 = Na2CO3 + H2O, the solid state is mixed with the two, and the reaction will also be slow), as long as the refractory substance is generated. In addition, there are no elemental substances in the reactants and products.

Refractory substances, such as water, gases that are insoluble in water, precipitates (such as barium sulfate), weak acids and bases (such as carbonic acid, ammonia), some salts that are difficult to dissociate (such as lead acetate, soluble in water but not ionized), complexes (such as EDTA chelation reaction), etc.

The displacement reaction, the condition is that the element with low electrode potential can replace the element with high electrode potential, and this property is listed as the "metal activity order table" for metals in middle school, which is actually arranged according to the electrode potential of the metal, and this is also incomplete, because non-metallic elements can also be replaced (Cl2+2Nabr=2NaCl+br2). To determine whether the displacement reaction can occur, just check the electrode potential meter.

There are no specific reaction conditions for chemical reactions and decomposition reactions.

Metathesis reaction:

There are requirements for both reactants and products. The reactants are mainly solubility problems, and there must be a precipitate, gas or water in the products, and the displacement reaction generally requires that in the order table of metal activity, hydrogen can be replaced by hydrogen in water or acid, and the metal in front can remove the metal from them.

of saline solution.

It's all chemical reactions. A chemical reaction is the creation of a new substance.

The arrow is preceded and followed by different substances, i.e., behind the arrows is the creation of new substances. So it's all chemistry.

The question may ask which are the options b and d that belong to the chemical reaction. Because a chemical reaction is defined as a reaction in which two or more substances react with each other to produce only one product.

The answer is questionable. ABCD should be chosen

The front and back are different substances, so it must be a chemical reaction.

Did you make a mistake in the question, where the compounding reactions are b and d?

Well, I haven't touched chemistry for a long time, and I don't know what to choose when I see such a basic problem...

Let's take a look at how the chemistry is described in the book.

This will deepen the memory.

Pick the fourth. There are chemical changes.

There's something wrong with the topic, it's all chemistry.

Calcined limestone: CaCO3 = (high temperature) CaO+CO2

Magnesium burns in carbon dioxide: 2 mg + CO2 = 2 mgo + c

The conditions of chemical reactions often include heating, ignition, high temperature, electrification, etc., and the use of " " indicates that there is gas generation in the reaction; " " indicates that there is a precipitate formed in the reaction

Therefore, the answer is: ignition, high temperature, electricity, etc.; ↑；

It's too cumbersome to type.,The chemical formula ruler is more troublesome than other stupid.,Handwritten to show you with a careful stove.,It may not be very clear.。

DA: Both of these substances are alkanes, so that's correct.

B: For example, methyl formate and acetic acid have the same molecular formula, but they are not homologues.

C: Correct. D: Same as example B.

Landlord, are you sure you made a mistake in your question? I don't think it's a double choice, it's a single choice, or your question is from an open-ended multiple choice question, which means that there are both single and multiple choices.

But I just found a question like yours on the Internet, and the answer is d.

Sometimes there are mistakes in the test paper, and I often make multiple choices in the single choice, or single choice in the multiple choice questions, or directly the answers are wrong.

1.Electrolysis of water.

2.Copper sulphate and iron.

3.Hydrogen combustion.

This one is the easiest, acid-base neutralization.