Which of the following statements is false? The following statement is false

Definitely go wrong with AD! But the explanations upstairs are all problematic!

Item A is not formaldehyde but methanol, and there is no problem with this.

But in item d, of course, there are benzene and toluene components in coal! How could it not be? A very important way to obtain aromatic hydrocarbons is through the dry distillation of coal, which is obtained from coal tar!

But d is wrong in the back, they can't be separated by the method of fractional distillation, because their boiling points are too close, benzene is degrees Celsius, toluene degrees Celsius. Such a small boiling point difference cannot be separated by fractionation.

The abc I made with the elimination method is all right glycerol is actually glycerol, so it's not oil, and dry ice is a solid of CO2, and it's not ice.

The composition of coal is usually called coal, and in some places it is customary to call it coal. But coal is not carbon. Coal is formed by ancient plant remains buried under the strata or in the earth's crust through a series of very complex changes.

It is a complex mixture of organic and inorganic substances, mainly containing carbon, in addition to small amounts of hydrogen, nitrogen, sulfur, oxygen and other elements, as well as inorganic minerals (mainly silicon, aluminum, calcium, iron and other elements).

Look it up elsewhere! ~

So I don't know why, because I didn't study chemistry, and you == someone else's.

AA industrial alcohol contains methanol.

b Glycerol is glycerol, from time to time oil, dry ice is CO2

c Coal is obtained by the long-term action of animal and plant corpses, so there are both organic and inorganic matter.

d Dry distillation separates the coal from the other two substances, and benzene and toluene are then fractionated, correct. So choose A

ADA is methanol, so it is false.

b Glycerol is glycerol, which is an alcohol; Dry ice is CO2, so it's correct.

c Common sense, correct.

It is true that benzene and toluene can be obtained by dry distillation of coal, but the coal itself does not contain benzene and toluene. Because dry distillation itself is a chemical separation method, it is to decompose the macromolecular substance into small molecules, and then obtain the fraction according to the different boiling points. Hence the error.

It should be chosen A, it should be said that industrial alcohol contains methanol, so it cannot be used to prepare beverages with industrial alcohol.

Is the following statement false?

a.The impulse is a vector quantity and the direction is the same as which is earlier in the force base.

b.The magnitude of the impulse is independent of the mass.

c.The impulse is equal to the product of force and stroke time.

d.Impulse is independent of momentum.

Correct Answer: Impulse is equal to the product of force and time.; Impulse is independent of momentum.

The opposite of d (+1 8) is 1 8, not -1 8

Answer B test question analysis: a, the concept of electric field: a special substance that exists around the charge and is produced by it So as long as there is an electric charge, there must be an electric field around the charge, this statement is correct, do not choose ab, the electric field does exist, it is a substance, not transferred by the objective will of people, not imaginary, this statement is not correct, there is no direct contact between the charges, but there will be a strong effect between them, this force is generated by the electric field, this statement is correct, Do not choose cd, the electric field force is the force of the electric field received by the charge in the electric field, so the electric field will have a strong effect on the charge put into it (whether it is stationary or moving), this statement is correct, do not choose d, so choose b test point:

Comment on the concept of electric field: This question is a simple question that reveals the nature of the electric field, which is a substance.

Answer C analysis: To answer this question, you need to master: how to correctly record the measurement results, and the accuracy of the measurement needs to be achieved, which is related to the requirements of the measurement

Answer: a. The accuracy of measurement needs to be achieved is related to the requirements of measurement, and has nothing to do with the person and tool of measurement, so a is correct

b. When recording the measurement results, the data and units should be recorded, and it is meaningless to write only the numbers, so B is correct

c. When recording the measurement results, the number of digits after the decimal point should be determined according to the accuracy of the scale used, not the more digits the more accurate the more digits are high accuracy, but the measurement results are not necessarily accurate, so c is wrong

d. When recording the measurement results, the size of the value is related to the unit used, the smaller the unit, the larger the value, so D is correct

Therefore, choose C Comment: This question mainly tests whether students can record the measurement results correctly, and the requirements for the accuracy of the measurement results

Answer D analysis: a. Compared with ordinary materials, nanomaterials have more special functions, such as copper particles become unable to conduct electricity when they reach the nanometer size; Insulating silica particles begin to conduct electricity at 20 nanometers For example, knives made of polymer materials and nanomaterials are harder than diamond products

b. Coal, oil, and natural gas are formed after a long geological time, and cannot be supplemented from nature in the short term, and are non-renewable energy, because of their non-renewable characteristics, so they need to be exploited in a planned manner;

c. The conductivity of semiconductor materials is between conductors and insulators, and the resistivity usually increases with the increase of temperature; If it is doped with reactive impurities or irradiated with light and rays, its resistivity can change by several orders of magnitude, which is used in the electronics industry and high-tech fields;

d. Malleability is one of the physical properties of matter, which refers to the degree to which it can be tempered and calendered, and silver ingots can be drawn into filaments, indicating that silver has good ductility

Answer: a. Nanomaterials have special functions in mechanical, thermal, acoustic, optical, electrical, magnetic and other aspects, so a is correct;

B. Coal, oil, and natural gas cannot be supplemented from nature in the short term, and it is not renewable energy, and the more non-renewable energy is used, the less it is, and it must be exploited in a planned way, so B is correct;

c. The conductivity of semiconductor materials can change with the change of various external factors, between conductors and insulators, so C is correct;

d. Silver ingots can be drawn filaments because silver has good ductility, so d is wrong

Therefore, choose D Comment: This is a comprehensive question, which examines nanomaterials, non-renewable energy, semiconductors and ductility, these knowledge points are rare in the usual questions, easy to ignore, and need attention

Answer D Analysis: According to the theory of molecular motion and its application in life Answer: According to the theory of molecular motion, the molecules of all objects never stop moving irregularly, so a, b, and c do not fit the topic

d. Pinch the bread by hand, the volume of the bread is reduced, there are air bubbles in the bread, which cannot prove that there is a gap between the molecules, so it is in line with the topic

Therefore, the selection d comment: The knowledge points of molecular kinetic theory and its application in life were examined

Answer D Analysis: Judge one by one according to the multiplication rule of rational numbers and the definition of opposite numbers Answer: a, true;

b. Correct; c. Correct;

d. The opposite of 0 is 0, 0 0=0

Therefore, the following concepts are used to answer this question:

1) Opposite number: Only two numbers with different symbols are called opposite numbers to each other, and the opposite number of zero is zero 2) Reciprocal: The product of two numbers multiplied by one is 1, and these two numbers are called reciprocal numbers to each other