There are as many reactions as possible for the following substances

Potassium dichromate is converted to potassium chromate under NaOH or KOH, a yellow solid that is easily soluble in water. (k2cro4)

HF can be neutralized with NaOH and KOH acids and bases to produce sodium fluoride and potassium fluoride, but the reaction is very violent.

Aluminum sulfide is produced by ignition of sulfur and aluminum, and the product is hydrolyzed when exposed to water and releases toxic hydrogen sulfide.

Iodine and sulfur are heated and combined.

Aluminum and iodine produce aluminum iodide in the presence of water, and the reaction is very beautiful!

Sodium chlorate reacts violently with aluminum, producing alumina and sodium chloride.

Boric acid, phosphoric acid, sodium hydroxide, and potassium hydroxide can also be neutralized to form positive salts or acid salts.

Fe+S==δ==Fes, insoluble in water, hydrogen sulfide is liberated when exposed to acidic water;

KNO3 is an oxidizing agent that can react with carbon, sulfur, sodium, magnesium, etc.;

Aluminum can reduce SiO2: Al + SiO2==Si + Al2O3, which can be ignited with potassium nitrate + magnesium strips.

Ammonium persulfate is a strong oxidizing agent and can react with carbon.

Cu and sulfur vapor can react, and the sulfur can be burned and boiled.

Sodium and water reaction: 2Na +2 H2O == 2NaOH + H2 sodium thiosulfate can also neutralize potassium persulfate oxygen.

Perchloric acid can react with ammonia to precipitate insoluble ammonium perchlorate. Ammonium perchlorate is decomposed by heat.

Magnesium reacts with perchloric acid to reduce hydrogen and chlorine dioxide.

The answer is C.

First of all, B is not right, ferric oxide and sodium hydroxide solution can not react, A can react, but white precipitate is generated, which is also not right.

d can also react, and there is also a white precipitate to form (or become turbid). Not right either.

Solution: A. Na2CO3 solution will generate white precipitate when added to clarified lime water, so this is wrong;

B. Fe2O3 is added to NaOH solution, and the two do not react, which is wrong;

C. Dilute HCl is dropped into Ba(OH)2 solution, and the neutralization reaction occurs, but there is no precipitation and gas generation, and there is no obvious phenomenon, so this item is correct

D. CO2 is passed into the clarified lime water, and the solution will become turbid, so C is selected for this error

1.Produces a white precipitate. na2co3+ca(oh)2=caco3↓+2naoh

2.It is supposed that FeCl3 reacts with NaOH to produce a reddish-brown precipitate. Fe2O3 does not react with NaOH. fecl3+3naoh=fe(oh)3↓+3nacl

3.There is no obvious phenomenon. ba(oh)2+2hcl=bacl2+2h2o4.Produces a white precipitate. co2+ca(oh)2=caco3↓+h2o

Both A and D produce turbidity, and B does not react, so the answer is C. Chloride is insoluble silver chloride and mercurous chloride, and bacl2 is a soluble salt. Therefore, HCl and Ba(OH)2 have a neutralization reaction, but there is no precipitation and no gas production.

The answer is C

Item C can be reactive, and there is no obvious phenomenon; Everything else has precipitation;

The landlord is entangled in "Isn't BACL2 precipitated", because the precipitation table is not well remembered. Both BaSO4 and AGCL are white precipitates, but BaCl2 is soluble in water to form a solution.

A. The reaction is: FeCl

fecl3fe(h

o)fecl2

znfe, so a is correct;

b、naalo2

If you don't want to return to the ear, you can directly generate al2 in one step

O3 should react with acid to form Al(OH)3

After that, pyrolysis is used to form Al2

o3 is therefore b error;

c. The reaction is: hno3cunoo

no2hohno3

Therefore c is correct; d. Guess the trembling hunger CO2mgco

cooco2 so d is correct hole touch.

Therefore, choose B

Whether a metathesis reaction occurs depends on whether the ion concentration decreases, i.e., whether precipitation, gas, and water are formed.

And whether the reactants are soluble or not, that is, there is acid or insoluble, and no acid needs to be soluble.

And in line with the redox reaction conditions, that is, strong acids can be used to make weak acids, and vice versa.

1.Yes because the reactants are acidic and produce water.

2.No ion concentration has not decreased, i.e. no precipitation, gas and water have been generated.

3.No ion concentration decreases, i.e. no silver difference is generated to precipitate, gas and water.

4.Yes, the reactants have acids and form carbonic acid, which is easily decomposed into water and carbon dioxide.

The answer is daMagnesium reacts with dilute sulfuric acid to produce magnesium chloride and hydrogen.

b.Zinc reacts with a copper sulfate solution to form zinc sulfate and copper.

c.Aluminium and silver nitrate are combined to form aluminium nitrate and silver.

This question examines the law of displacement reactions, in which the metal in front of the metal in the order of activity table can replace the metal (or hydrogen ion) in the back. d The mercury is behind the copper and cannot be replaced.

The metal activity of mercury (Hg) in option d is after copper (Cu), so mercury cannot be displaced from the aqueous solution of copper to produce elemental copper, so it cannot react.

d.Hydrochloric acid and carbon dioxide.

Because carbon dioxide dissolves in water to produce carbonic acid, acid does not react, so D is chosen

1. Na2CO3 + 2Hno3 === H2O + CO2 (gas) + 2nano3

2. K2SO4+HNO3 cannot: reactants are soluble 3, CuCl2+Fe(OH)3: No:

The salt solution does not react with insoluble alkali 4, Ca(OH)2+Na2CO3===2NaOH+CaCO3(precipitate)5, Cu+HCl: No: the activity of copper is behind hydrogen 6, Zn+MgSO4:

No: the activity of zinc is behind magnesium.

The sodium carbonate solution limb was added to the clarified lime water, and the phenomenon was that the clarified lime water became turbid and hail hungry. The reaction equation is as follows:

na2co3+ca(oh)2=caco3↓+h2o