Find a few chemistry problems and solve a few chemistry problems

Main family elements. The highest positive price is the ordinal number (except for the family).The sum of the absolute value of the lowest price and the highest positive price is 8

Now know that they differ by 4Comparing 1-7 main families yields a maximum positive value of +6 and a negative value of -2

is the sixth main element.

The most stable should be the seventh main element.

Gaseous hydrides are associated with the lowest price. H is +1, so the chemical formula is H2R2It can be determined that the former maximum is +5

So the minimum is -3The gaseous hydride is H3X

Hydrogen occupies, so the formula amount is 3

X is 64 grams more than the AS mole of HXROY than the 1 mole of HXR.

The mass of more ymol oxygen is 64g

The total number of electrons outside the nucleus of r in hxroy of y = 41 moles is 16 moles less than that of hydrogen and oxygen.

Hxro4O has 8 electrons. h has 1.

There are x+32 electrons in total.

16 less means 16+x electrons.

Because it is the third cycle, the number of electrons is up to 18.

x can only take 1 proton number as 17

So the atomic number is 17It's cl

Not necessarily. The outermost layer of he, cu, and zn is also 2

c.From cycle 4 onwards, there is an over-element next to the second main group, which is obviously not.

But MN is not a primary element.

1) If the most ** is x, the lowest price is x-8∴x+(x-8)=4.Cycle 6 d

2) The highest positive price is +5, so the negative price is -3Rh3 753) is known to have 64 grams more Hxroy mass than 1 mole of Hxr y=4 Let R be the main group of p, the total number of electrons outside the nucleus of R is 10+p, and the total number of electrons outside the nucleus of hydrogen and oxygen atoms.

8y+(2y-p) (x+p=2y∴x=2y-p) ∴10+p+16=8y+(2y-p)

So p=7 so atomic number 17

4) d a) subfamily e.g. cu b) semi-filled c subfamily.

I'm also not quite sure why d is right.

1.Suppose 50g of 98% sulfuric acid can be prepared into 20% of sulfuric acid x grams, sulfuric acid mass balance: 50 * 98% = x * 20% x = 245 grams.

The amount of water to be added is: 245-50 = 195 grams.

Special attention: when preparing dilute sulfuric acid, do not pour water to acid, in case of liquid splashing).

2.The composition of the filter residue is to determine which solids are still present. Because there are silver ions in the solution, it means that the amount of iron is not enough to replace all the silver, and all of it is reacted into iron ions, and part of the silver becomes a precipitate.

Whereas, iron does not react with zinc ions. It should be c, only silver ag.

1 H2SO4 quality unchanged, later think yourself.

2 C (means that there is still Ag+ in the solution, so the filter residue is only Ag).

The first question will definitely not be done, because the water will be heated and evaporated, which can only tell you to add water to the whole solution with a constant mass of 245g.

Why? 50g of H2SO4 solution contains 49g of H2SO4, so 49g 20% = 245g

The first step is to add iron, because the order of activity of iron is after Zn and before Ag, so Fe will become Fe2+, and Ag+ will become Ag. Then add NaCl to have a white precipitate, so there is still AG in the solution, so there is no iron in the filter residue. So there is only ag

1.The mass of H2SO4 is: 50* The total mass after preparing 20% sulfuric acid is: 48 So water should be added: 240-50=190g

2. c。The reaction between the nitrate solution and the NaCl solution can only produce AGCL, so the nitrate solution is added.

Fe powder, the new nitrate solution formed after full reaction still has the presence of AGNO. Therefore, Fe and Agno are not completely reacted, so there should be only Ag in the filter residue.

1) I didn't understand it.

2) Because aluminum reacts with oxygen to form a dense film, alumina, to prevent aluminum from being further oxidized, and iron is oxidized to form a dark red loose substance, which cannot prevent iron from being further oxidized, so aluminum products are more corrosion-resistant than iron products, and the chemical equation is: 4Al+3O2=2Al2O3

3) Reacting with oxygen is fake, not reacting is real. Because real gold is not afraid of fire, the chemical properties of gold are stable.

2cu+o2=(heating)2cuo

1) The mass ratio of sulfur in sulfur dioxide gas to sulfur trioxide gas is 5*1, which is 5SO2

and SO3, 5SO2

Mass = 5 32 + 16 2 = 320, SO3 mass = 32 + 16 3 = 80

The mass ratio of sulfur dioxide to sulfur trioxide is 320:80=4:1Pick B.

1. After mixing, the thick Hedu shirt is (2*52%+3*38%) 2+3)=

2. It is necessary to add or concentrate hydrochloric acid to 100*10% (37%*).

The volume of water that needs to be added is (

1.Acid Hno3 Base Fe(OH)2 or Fe(OH)3 Salt Fe(NO3)3 or Fe(NO3)2 (you don't standardize the valency, the compound is uncertain).

2.If you can't do it, you can see for yourself: soluble in water and reduced in volume Soluble in lime water, the volume decreases c and d should not.

3.NaCl and HCl do not react Na2CO3+2HCl=2NaCl+CO2+H2O

1) m(Na2CO3)=106 10= m(NaCl)=(2) The solute after the reaction is NaCl, and its mass is:

The mass of the solution is w=18

In the first question, y > z>x, according to the order of activity, y is in front of h, xz is after h, and z is replaced by x, which means z is in front of x.

In the second question, choose C, the mass of mg plus Cu is twice that of Cuo, x+64=2*(64+16), then x=96, 64:96=2:3

The third question, choose b, Zn can be replaced by Fe and Ag, so there must be iron and silver, and zinc may be all replaced or more, not necessarily.

The fourth question, d,2Fe+3CuCl2=2FeCl3+3Cu, Fe and Cu are solids, and according to the conservation of mass, the mass of the solution becomes lighter.

1) Y>x>z directly produces gas, indicating that y is a reactive metal, and x displaces z, indicating that x is more active than z.

2) c reacts with acid, magnesium is all consumed, copper is oxidized, assuming there is nmoi, the mass is 80N, the total mass is 160N, the copper is 64N, the magnesium mass is 96N, and the mass ratio is 2:3

3) b The activity of silver is the weakest, so it is precipitated first, and zinc and iron can react with hydrochloric acid to release gas, so there must be iron in the mixture, but zinc may not be there.

4) d reacts with dilute hydrochloric acid and dilute sulfuric acid to release gas, but the iron is dissolved, the mass of the solution increases, it does not react with ferrous sulfate, the quality of the solution does not change, and the iron can replace the copper in the copper chloride solution, the mass: copper" iron, so the quality of the solution decreases.

In the physical change, the molecule of the substance does not change, but the volume changes, and in the chemical change, the molecular structure changes, giving rise to the molecules of other substances.

A molecule is a particle that makes up matter, and he represents a microscopic concept.

The following statement is wrong (c).

a.Elemental matter must be made up of one molecule bAir is a mixture of multiple components.

c.A substance composed of only one molecule must be pure CThere is definitely more than one type of atom contained in the molecule of a compound.

Among the following changes, the particles that make up matter have undergone essential changes (d).

a.Alcohol and water blend with each other bSugar dissolves in water cSalt crystals are obtained by evaporation of salt water.

d.Carbon dioxide is introduced into the clarified lime water, which becomes turbid.

When the steamed bread encounters solid iodine, the iodine solution and iodine vapor can turn blue, which illustrates (a).

a.A molecule is the smallest particle that maintains the chemical properties of a substance.

b.The smallest particle in a chemical change in molecular formula.

c.A molecule is a type of particle that makes up matter.

d.Molecules are separable in chemical changes.

The molecule of a compound is made up of multiple atoms, and the molecule of a single element is made up of a single atom. In a chemical change, the atoms of the molecules that make up the reactants reconstitute a new molecule

The following statement about filtration is incorrect (a c).

a.Filtration is the separation of an insoluble liquid (?) from a liquidSolid? ).

b.The liquid should be injected into the funnel along the glass rod.

c.To speed up filtration, a glass rod should be stirred.

d.The filter paper in the filter should be close to the inner wall of the funnel.

Why does the water purification in the waterworks have to be disinfected at the end? (Be brief).

Because chlorine is also poisonous... So disinfect ......-

In the physical change, there is no change, only there is a change, and in the chemical change, there is a change, and the molecules of other substances are formed.

A molecule is a microscopic particle that denotes a microscopic concept.

The following statement is wrong (c).

a.Elemental matter must be made up of one molecule bAir is a mixture of multiple components.

c.A substance composed of only one molecule must be pure CThere is definitely more than one type of atom contained in the molecule of a compound.

Among the following changes, the particles that make up matter have undergone essential changes (d).

a.Alcohol and water blend with each other bSugar dissolves in water cSalt crystals are obtained by evaporation of salt water.

d.Carbon dioxide is introduced into the clarified lime water, which becomes turbid.

When the steamed bread encounters solid iodine, the iodine solution and iodine vapor can turn blue, which illustrates (a).

a.A molecule is the smallest particle that maintains the chemical properties of a substance.

b.The smallest particle in a chemical change in molecular formula.

c.A molecule is a type of particle that makes up matter.

d.Molecules are separable in chemical changes.

The molecule of a compound is made up of 2 or more atoms, and the molecule of a single element is made up of 1 atom. In a chemical change, the molecules that make up the reactants are reconstituted into new ones

The following statement about filtration is incorrect (c).

a.Filtration is a method of separating insoluble liquids from liquids.

b.The liquid should be injected into the funnel along the glass rod.

c.To speed up filtration, a glass rod should be stirred.

d.The filter paper in the filter should be close to the inner wall of the funnel.

Why does the water purification in the waterworks have to be disinfected at the end? (

Sterilization back. Degradable substances have been removed.

I did my best.

In physical change, there is no change in (both molecules and atoms), but only in (state) change, and in chemical change, (both properties and mass) change, molecules of other substances are formed.

A molecule is a particle (that retains its chemical properties), which represents a microscopic concept.

a.Elemental matter can be directly composed of atoms, such as helium is made up of helium atoms.

d.There was a chemical change.

c.A molecule is a type of particle that makes up matter.

The molecule of a compound is composed of two or more atoms, and the molecule of an element is composed of one or more atoms. In a chemical change, the molecules (atoms) that make up the reactants are reconstituted into new ones.

a.Filtration is a method of separating solids from liquids.

Disinfect with alum to make impurities such as dust precipitate faster; Disinfection with hypochlorous acid is sterilizing.