Ask a few chemistry questions, note that change is not a property, but also a reason 50

Air is a gas without color and odor: physical properties.

Grain as a raw material can make wine: chemical properties (changes).

The density of copper is, and the melting point is 1083 degrees: physical properties.

Carbon dioxide can make clarified lime water turbid: chemical properties (change).

The first sentence is nature! Physical. Because these properties have nothing to do with chemical reactions.

The second sentence ......It should also be chemical. But it can be said that the chemical changes are related to the anaerobic respiration of yeast. For details, read the biology book (junior high school has it, and it talks about fungi).

The third sentence is also physical! It is also not related to chemical reactions.

The fourth sentence is chemical properties (it is okay to say chemical change, but the expression is properties). Because this property requires a chemical reaction (CO2 + Ca(OH)2 = CaCO3 (precipitation) + H2O, new substances are formed) to be revealed.

What a strange question......

You're asking about "change", but it's definitely nature! You just change the word "nature" to "change". However, like the first and third, there is no change in this sentence at all!

In the other two, it is not a change to say "can". It's like saying that you can do this question, but it doesn't mean that you have done this question! This is just about "nature" (will do), not "change" (done).

..lz..It's very simple. First of all, chemical changes are the creation of new substances. Physics is not.

The first. airy. It's physics because he hasn't changed. No new matter is generated.

The second. Winemaking. It's chemical, because he produces new substances.

The third. density. It's also physical because he doesn't change. No new matter is generated.

The fourth. carbon dioxide. And this is chemical, because the clarified lime water becomes cloudy, which means that new material is formed.

1.Air is a mixture, and the composition does not change when there is no change in temperature and pressure. (See the concept of degrees of freedom in physical chemistry).

2.Grains are mainly composed of starch and polysaccharides, and in the process of winemaking, starch is hydrolyzed to form monosaccharides (lactulose and glucose), which are further decomposed into alcohols. Alcohols are then oxidized to become aldehydes and even acids. The wine is sour.

3.Density and melting point reflect the properties of the monomer, which do not change until the monomer reacts or changes its crystal shape.

Ca(OH)2 and CO2 in water react to form calcium carbonate precipitates.

The r element is sThe highest oxide has a relative molecular mass of 80 and is known to be SO3.

The hydrate corresponding to the most ** oxide of calcium is.

Ca(OH)2 so the relative molecular mass is 74

Calcium is element 20, so the atomic structure is 4 layers, from the inside to the outside, in order of 2, 8, 8, 2

Hello. 1) Chemical properties refer to the properties that occur when a chemical reaction occurs.

Whereas, a is a physical change, and there is no material change.

c and d are both physical properties.

2）a。Because there is CO2 dissolved in Sprite, there is carbonic acid in the Sparrow, dripping.

Purple litmus turns red, but when the carbonic acid is heated and decomposes, the carbonic acid will decompose and the color will fade.

3）d。Because it is H2CO3 (acid) and not CO2 that changes the color of the purple litmus paper, it is not possible to do it "dry".

Thank you for the high age. Good luck with your studies.

1c Dry ice rainfall is sublimated, endothermic, physical.

Activated carbon adsorption.

Diamond is hard.

In 2D, carbon dioxide reacts with water to form carbonic acid electricity, which leaves the hydrogen ion collapse front, which is acidic first, making litmus red.

Ba is the physical and clever property of CO2, C is adsorption, D is hardness, and B, and combustible ice is denier methane with crystalline water.

A At first, the acidity makes the test strip red, and then the CO2 overflows and turns purple.

DCO2 can only be acidic when it is dissolved in water to form a carbonic acid pin.

1.Option B takes advantage of the flammability of CH4.

A is the use of dry ice temperature is very low, so it is a physical property.

c is the adsorption with activated carbon, so it is a physical property.

d. Diamond hardness,So it's a physical property of Ponna.

2. Sprite is a carbonated drink containing H2CO3, which is acidic and makes the purple litmus solution red. Heating H2CO3 decomposes into CO2 and H2O acidity disappears, so it turns purple.

3. Select DH2O+CO2=H2CO3 acidity.

aLime water is alkaline.

Turn blue. b neutral.

No change. cAcid gas.

However, it is not acidic when dried.

1. A soluble in rivers, rivers and lakes: carbon dioxide is both soluble in water and reacts with water; b is absorbed by lime water is carbon dioxide and calcium hydroxide reaction.

c. Support dry ice (made into dry ice) carbon dioxide into solid.

Participate in photosynthesis, which you learned in biology class, is chemical change.

2. Activated carbon makes the magenta solution fade by using the adsorption and physical changes of activated carbon.

Copper sulfate crystals lose part of the crystal water when heated and the copper sulfate crystals are decomposed by heating.

Carbon monoxide is inhaled into the lungs and binds to hemoglobin in the blood, which is a chemical change.

The reddening of phenolphthalein test solution when exposed to alkali is a chemical change.

Heated saturated and clarified lime water becomes turbid, and it is turbid. It is because the solubility of calcium hydroxide becomes smaller, and you will know it when you learn the unit "solution".

3. The displacement reaction is a reaction in which the element and the compound react to form the element and the compound, so there must be the generation of the element.

1 Among the following methods of obtaining oxygen, the one that is considered a physical change is ( ).

a. Electrolyze water b. Heat potassium permanganate

c. Separation of liquid air d. Heating the mixture of potassium chlorate and a small amount of manganese dioxide

2 The properties of the following substances are chemical ( ).

Hydrogen is flammable, oxygen is a colorless gas, and carbon dioxide is twice as dense as air;

Carbon monoxide is reducing, acid solution can make litmus solution red, carbon monoxide is toxic. 

a、①②b、④⑤c、①④d、②③

3. The following changes are chemical changes ( ).

a. Ice melts into water b. Wood burns c. Chalk is ground into powder, and stones are carved into stone statues.

E, animal respiration f, purification of coarse salt g, solder melting h, white sugar turns black when exposed to concentrated sulfuric acid i, diamond turns into graphite j, plant light and action k, boiler occurrence ** m, electric light emitting heat n, saturated lime water at room temperature becomes turbid after heating o, lime water becomes turbid after entering an appropriate amount of CO2 p, lumpy quicklime gradually turns into white powder in the air q, bile alum slowly turns from blue to white under heating r, concentrated hydrochloric acid is stored openly, and the concentration becomes smaller after a period of time s, CO2 turns purple litmus reagent red, and iron products are corroded in the air.

4. The following changes will not occur in the process of chemical change ( ).

a. Zinc granules are soluble in dilute hydrochloric acid b. Diluted concentrated hydrochloric acid

c. White phosphoryl dew is placed in the air d. Copper powder is heated in the air

5. The basis for judging that the combustion of iron wire in oxygen is a chemical change is ( ).

A. A large amount of heat is emitted B. Sparks are radiant C. Iron wire melts into balls D. Black Fe3O4 is generated

6. The following changes must be chemical changes ( ).

a, ** b, combustion c, sublimation d, discoloration e weathering f deliquescent.

7. Distinguish the following groups of substances by simple methods, generally according to the chemical properties to distinguish ( ) a, water and gasoline b, water and clarified lime water c, sugar and salt d, copper wire and iron wire

Choosing BCB hard water will produce scum stearic acid with soapy water, also known as octadecylic acid, saturated fatty acid. The chemical formula is C17H35COOH, a solid that is insoluble in water, with a density less than water, weakly acidic, and cannot change the color of litmus solution. It is one of the products of oil hydrolysis.

It reacts with sodium hydroxide to form sodium stearate, commonly known as hard soap.

Hard water contains more calcium, magnesium, and plasma, and it is easy to combine stearic acid in soap to form calcium stearate and magnesium stearate that are insoluble in water. These precipitates are suspended solids.

c17h35coo- +ca2+ = ca(c17h35coo-)2

c17h35coo- +mg2+ = mg(c17h35coo-)2

c Soapy water adsorbs the metal of hard water is a chemical change, which is introduced as soap containing sodium stearate, which will react with magnesium ions and calcium ions in hard water to form magnesium stearate and calcium stearate precipitation, which is a chemical change.

b.Limescale is formed when hard water is heated, which is a chemical change.

c.Soap is chemically dissolved in hard water and undergoes chemical changes with hard water.

c. Soap is dissolved in hard water and reacts with some metal elements in hard water, such as magnesium, to form a precipitate.

The answer is correct, hard water contains calcium and magnesium ions to form insoluble calcium and magnesium compounds after heating, and the higher fatty acid salts in the soap (mainly sodium of higher fatty acids) react with the calcium and magnesium plasma in hard water to form a precipitate.

True or False H2O molecule.

Wrong: Air is a mixture, and if it's a molecule, it's pure, and noble gases are made up of atoms, and air can only contain noble gases.

A false molecule is a particle that keeps the chemical properties of a substance to a minimum.

Error n278%, o2 21%.

Chemistry is a kind of natural science, which studies the composition, properties, structure and change laws of matter at the molecular and atomic levels. The science of creating new matter. The world is composed of matter, and chemistry is one of the main methods and means used by human beings to understand and transform the material world.