Can someone help me pls I don’t have time Time is almost ran out pls help

Answer:

The arrow going directly from the sun to the earth (middle one)!

Explanation:

HOPE THIS HELPS! :)

Answer:  Pb(NO3)2(aq) + 2KI(aq)  —> PbI2(s) + 2KNO3(aq)

1.57x10^22 atoms of Pb

87% yield

Explanation:

10.0 g Pb(II) nitrate = 10/333 moles = 0.03 moles

12.0 g KI = 12/166 moles = 0.072 moles (0.06 moles required)

11.4 g PbI2 = 11.4/421 moles = 0.026 moles

expected yield 0.03 moles, yield = 87%

atoms in 11.4 g = 0.026 moles = 0.026*6.02214076*10^23 atoms = 1.57*10^22

Answer:

This kind of interaction can be expected between any polar molecule and non-polar/symmetrical molecule. The induction-interaction force is far weaker than dipole–dipole interaction, but stronger than the London dispersion force.

Answer:

[tex]m_{Cr_2O_3}^{actual}=62.4gCr_2O_3[/tex]

Explanation:

Hello!

In this case, according to the reaction:

[tex]4Cr+3O_2\rightarrow 2Cr_2O_3[/tex]

We can see there is a 4:2 mole ratio between chromium and chromium (III) oxide, this, for the given 56.2 g of chromium, the theoretical yield of the oxide product is computed down below:

[tex]m_{Cr_2O_3}^{theoretical}=56.2gCr*\frac{1molCr}{52.0gCr}*\frac{2molCr_2O_3}{4molCr} *\frac{151.99gCr_2O_3}{1molCr_2O_3} =82.13gCr_2O_3[/tex]

Now, considering the 76.0-% yield for this reaction, the actual yield turns out:

[tex]m_{Cr_2O_3}^{actual}=82.13gCr_2O_3*\frac{76.0gCr_2O_3}{100gCr_2O_3} \\\\m_{Cr_2O_3}^{actual}=62.4gCr_2O_3[/tex]

Best regards!

Answer:

False

Explanation:

Answer: For most of the life the chromosomes exists in a loose noodle like structure. They become compact to fit into a very small space.

Explanation: The chromosomes consists of a very long DNA that is linear. The liner DNA also has many proteins associated with it which is called as histone proteins.

These proteins fold and gets packed into a compact form from loose noodle or thread like structure.

This is necessary to get into a compact structure because being in linear form would require much space which is not possible. So as to manage the space and many processes like replication, repair and gene expression it is necessary for the chromosomes to get compact.

Answer:

-273.15 degrees celsius

Answer:

Compound 1 - Can't decide

Compound 2 - Can't decide

Compound 3 - molecular

Explanation:

The solid that has been designated as compound 1 is difficult to really classify because, we can see that the solid only became hot when heated but does not soften. This can be an attribute of an ionic solid. However, the same solid is not soluble in water. This insolubility in water is a property of molecular solids. As a result of these, we will find it difficult to classify the solid.

Compound 2 is also difficult to decide upon because ionic solids are crystalline and can not be ground into powder. Amorphous substances can be ground into powder easily. Then, we can see that the substance does not conduct electricity in block form but does so when moistened. This means that we can not conveniently classify it as a molecular solid since molecular substances do not conduct electricity.

A molecular substance usually has a low melting and freezing point and also does not conduct electricity hence compound 3 is molecular solid.

Answer:

A

Explanation:

An ion is a particle, atom or molecule with a net electrical charge.

Answer:

C. An element that has an unequal number of protons and electrons

Explanation:

An element has an equal number of protons and electrons, because the positive and negative energy has to cancel out so the atom is neutral. Ions are versions of atoms that lose electrons so they have a different energy than the initial atom, but they're still that atom because the number of protons determines the identity of the atom, and that number doesn't change.

First you have to find the number of moles , then you have to apply stoichometry to find the number of moles of H2 gas , after that you can determine its mass.

Answer:

the entropy of this system is 4.9452  × 10⁻²³ J/K

Explanation:

Given the data in the question;

we take a look at the Boltzmann formula for entropy;

s = k × In( W )

k is the Boltzmann's constant ( 1.38 × 10⁻²³ m² kg s⁻² K⁻¹ )

W is the number of energetically equivalent possible microstates or system configurations ( 36 )

so we substitute

s = 1.38 × 10⁻²³  × In( 36 )

s = 1.38 × 10⁻²³ × 3.5835

s = 4.9452  × 10⁻²³ J/K

Therefore, the entropy of this system is 4.9452  × 10⁻²³ J/K

Answer:

no of valence electrons

Explanation:

because valence electrons are the electrons present in the outer orbital

Answer:

its actually the number of shells

Explanation:

valence electrons are the same down any group. atomic orbitals, or shells, are the same across periods

Answer:

By the end of this module, you will be able to: ... (a) Calculate the pH of an acetate buffer that is a mixture with 0.10 M acetic acid and 0.10 M ...

Answer:

Susie cooked sausages on a barbecue. (a) Fat and water in the sausages changed state. Draw one line from each statement to the correct change of state.

Explanation:

brailest/ crown please

Answer:

When stargazers go outside at night to look at the sky, they see the light from distant stars, planets, and galaxies. Light is crucial to astronomical discovery. Whether it's from stars or other bright objects, light is something astronomers use all the time. Human eyes "see" (technically, they "detect") visible light.

Answer:

Image result for why is light important in astronomy?

When stargazers go outside at night to look at the sky, they see the light from distant stars, planets, and galaxies. Light is crucial to astronomical discovery. Whether it's from stars or other bright objects, light is something astronomers use all the time. Human eyes "see" (technically, they "detect") visible light.

Explanation:

Answer:

Electrons repel each other due to electrostatic force of attraction between both of them as a result prevent the electron from entering the nucleus preventing it from collapsing

Electrons repel each other because they have the same charge present in

them.

Law of magnetism states that:

Electrons are subatomic particles which are negatively charged which

depicts them possessing like poles.

This explains why electrons which are in contact with each other will repel as

a result of the repulsive force present in like poles.

Read more about Law of Magnetism here https://brainly.com/question/12529206

Answer:

[tex]V=14.76mL[/tex]

Explanation:

Hello!

In this case, since the given 5.00 % (w/v) can also be represented in terms of mass of solute over volume of solution, we need to make sure that the same system of units is used, in this case, the appropriate units for that unit of concentration should be g/mL, and therefore, we first need the mass of citric acid in grams:

[tex]m=738mg*\frac{1g}{1000mg} =0.738 g[/tex]

Thus, by using the w/v percent, we obtain the following volume of solution:

[tex]V=\frac{m}{m/w}*100\%[/tex]

So we plug in to obtain:

[tex]V = \frac{0.738g}{5.00\%}*100\% \\\\V=14.76mL[/tex]

Best regards!

Answer:

19

Explanation:

Here,

[Ar] = Argon = atomic no. = 18

4s1 = 1 electron

so 18 + 1 = 19

19 = Potassium (K)

Answer:

A - combustion

B - photosynthesis

C - respiration

The chemical change involved in each action is combustion, photosynthesis and respiration respectively.

Chemical changes are defined as changes which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical change.

There are several characteristics of chemical changes like change in color, change in state , change in odor and change in composition . During chemical change there is also formation of precipitate an insoluble mass of substance or even evolution of gases.

There are three types of chemical changes:

1) inorganic changes

2)organic changes

3) biochemical changes

During chemical changes atoms are rearranged and changes are accompanied by an energy change as new substances are formed.

Learn more about chemical change,here:

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Answer:

the IS unit for measuring the amount of a substance

Explanation:

that's what it is

Answer:

Explanation:

It probably would have been broken down to smaller pieces and spread out around the world. Hope this help! :)

To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil.

Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.

In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.

Each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil. This conclusion was the direct result of the gold foil experiment.

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Answer:

[tex]87.3 + 0.001 = 87.301[/tex]

[tex]0.201 + 0.92 =1.121[/tex]

[tex]320 + 8.41 =328.41[/tex]

[tex]1200-60=1140[/tex]

Explanation:

Solving (a): 87.3 + 0.001 =

87.3 --> 3 significant figures

0.001 --> 1 significant figure

So, the answer must be in at least 3 significant figures

[tex]87.3 + 0.001 = 87.301[/tex]

Solving (b): 0.201 + 0.92 =

0.201 --> 3 significant figures

0.92 --> 2 significant figures

So, the answer must be in at least 3 significant figures

[tex]0.201 + 0.92 =1.121[/tex]

Solving (c): 320 + 8.41 =

320 --> 2 significant figures

8.41 --> 3 significant figures

So, the answer must be in at least 3 significant figures

[tex]320 + 8.41 =328.41[/tex]

Solving (d): 1200 – 60 =

1200 --> 2 significant figures

60 --> 1 significant figure

So, the answer must be in at least 2 significant figures

[tex]1200-60=1140[/tex]

The number of particles of atoms depends on the ratio of their composition in the compound

Given

5.432 g of table sugar

Required

moles of sample

moles of C, H and O

number of atoms

Solution

Table sugar : Sucrose : C₁₂H₂₂O₁₁

= 5.432 : 342,3 g/mol

= 0.016

C = 12 x 0.016 = 0.192

H = 22 x 0.016 = 0.352

O = 11 x 0.016 = 0.176

C = 0.192 x 6.02 x 10²³ = 1.16 x 10²³

H = 0.352 x 6.02 x 10²³ = 2.12 x 10²³

O = 0.176 x 6.02 x 10²³ = 1.06 x 10²³

Answer:

2.3?

Explanation: