There are many important laws and theories in science. Which of the following is a law of science?
A living thing is made of at least one cell.
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An atom is made of electrons orbiting a nucleus.
Gravity will pull two objects toward each other.
Natural selection will change species to fit their environments.

Answer:

Explanation:

1:) A

Mostly just use context clues

2:) D

The climate on earth is mostly due to earth's atmosphere. So, no, the moon doesn't have similar weather

Answer:

The ability to do work is energy.

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According to the mole concept, there are 4.54 moles present in 200 grams of carbon dioxide.

Mole is defined as the unit of amount of substance . It is the quantity measure of amount of substance of how many elementary particles are present in a given substance.

It is defined as exactly 6.022×10²³ elementary entities. The elementary entity can be a molecule, atom ion depending on the type of substance. Amount of elementary entities in a mole is called as Avogadro's number.

It is widely used in chemistry as a suitable way for expressing amounts of reactants and products.For the practical purposes, mass of one mole of compound in grams is approximately equal to mass of one molecule of compound measured in Daltons. Molar mass has units of gram per mole . In case of molecules, where molar mass  in grams present in one mole  of atoms is its atomic mass.Number of mole= mass /molar mass which is 200/44=4.54 moles

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Answer:

There are 54.03 grams in 3 moles of H2O

There are 3.2 moles in 519.3 g FeCl3

There are 56.0 g in 2 moles of CO

Explanation:

H2O molar mass: 18.01 g/mol

   to calculate the grams:  3 mol H2O * 18.01 g/mol

FeCl3 molar mass: 162.2 g/mol

   to calculate moles:  519.3g FeCl3 / 162.2 g/mol

CO molar mass: 28.01 g/mol

   to calculate grams: 28.01 g/mol CO * 2 mol CO

Answer:

288g

Explanation:

Given parameters:

Number of moles of H₂O  = 16moles

Unknown:

Mass of the water = ?

Solution:

To solve this problem, first find the molar mass of H₂O;

     Molar mass of H₂O = 2(1) + 16  = 18g/mol

Mass of H₂O = number of moles x molar mass

                      =  16 x 18

                      = 288g

Answer:

4d orbital.

Explanation:

Hello!

In this case, since zirconium's atomic number is 40, we fill in the electron configuration up to 40 as shown below:

[tex]1s^2,2s^2,2p^6, 3s^2,3p^6,4s^2,3d^{10},4p^6,5s^2,4d^2[/tex]

Thus, the orbital 4d is partially filled.

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This question is incomplete, the complete question is;

A 17.0 g sample of quartz, which has a specific heat capacity of 0.730 J.g⁻¹°C⁻¹, is dropped into an insulated container containing 200.0 g of water at 85°C and a constant pressure of 1 atm . The initial temperature of the quartz is 7.2°C.  

Assuming no heat is absorbed from or by the container, or the surroundings, calculate the equilibrium temperature of the water. Be sure your answer has the correct 3 number of significant digits.  

Answer:

the equilibrium temperature of the water is 83.9°C

Explanation:

Given the data in the question;

Since no heat is absorbed from or by the container, or the surroundings;

Then  Heat lost by the quartz = heat gained by water

ΔH1 = ΔH2

DH = mcΔT

where m is mass, C is specific heat capacity and ΔT is temperature change;

so

(mcΔT)1 = (mcΔT)2

we know that; specific heat capacity of is 4200 Joule/Kilogram K (J/kg∙K) = 4.2 (J/g∙°C)

we substitute

17.0g × 0.730 J.g⁻¹°C⁻¹ × ( 7.2°C - T2)  = 200.0g × 4.2 J/g∙°C × ( T2 - 85°C)

89.352 -  12.41T2 = 840T2 - 71400

840T2 + 12.41T2 = 89.352 + 71400

852.41T2 = 71489.35

T2 = 71489.35 / 852.41 = 83.86°C ≈ 83.9°C

Therefore, the equilibrium temperature of the water is 83.9°C

Answer:

The bending of light as it passes from one medium to another is called refraction

Explanation:

Answer:

The lumps should be removed in brown sugar and to be rolled with rolling pin.

Explanation:

In preparing brown sugar as ingredients in baking and pastry, it is important to check if the sugar is lumpy. Although it is not the main ingredient in baking, it is important to check because it could affect the texture of the mixtures. Brown sugar is also much nutritious to white sugar  that is why it is more commonly use. The brown sugar become lumpy because when brown sugar is exposed to air it gets harder because the molasses that keeps its soft evaporates that makes the sugar stick together. The rolling pin helps the lump to break up.

Answer:

To answer this question we would need the Molecular empirical formula that relates the reactant of N2 to the final product of CH3NH2. Then it would be easily solved by using stoichiometric ratios. Basically it is done similar to unit conversion problems.

Answer:

Hate to take up this answer spot, but there is no statements about phase changes.

Here are some phase changes to help: when matter changes phase.  Most common ex. is water(liquid) to ice(solid).  It is created by particles coming together, or spreading apart.

Brainliest?

Answer:

4 orbits in the fourth period.

19 electrons in the atom from group 1 and fourth period.

Explanation:

Potassium has 19 electrons distributed in its 4 orbits

The number of periods in a periodic table, tells the number of shells or orbitals of the atoms in that row in which the electrons are filled. Thus the fourth period elements have 4 orbitals and the first element in group one of the fourth period is potassium containing 19 electrons.

All elements in a periodic table are classified into different groups and periods. The vertical columns in the periodic table is called groups and the horizontal rows are called periods.

A group contains elements with same number of valence electrons and similar physical and chemical properties. In a period from left to right the atomic number increases but the number of orbitals in which the electrons are filled will be the same.

Down a group the number of orbitals increases by one. Thus, each elements contains electrons in an increment of 8, 18, 18 and 32 down a group. Thus, from third period to fourth period the number of orbital increases to 4.

The number of electrons will be +8 from the previous element in the group in third period. Thus, below sodium (11) the first element in fourth period is potassium with 19 electrons.

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Answer:

The group number in the periodic table represents number of valence electrons of the elements in a certain group.

Explanation:

There are s, p, d, and f blocks, which you can see in periodic table

The s-block and p-block together are usually considered main-group elements, the d-block corresponds to the transition metals, and the f-block encompasses nearly all of the lanthanides (like lanthanum) and the actinides (like actinium)

There are three main principles, which may useful for you:

Hope this helps!

Answer:

[tex]n_{FeS}=0.686molFeS \\\\n_{H_2S}=23.3gH_2S[/tex]

Explanation:

Hello!

In this case, according to the given chemical reaction, it is possible to apply the following stoichiometric setups in order to compute the moles of reacting FeS and the grams of produced H2S, given the mass of HCl (molar mass = 36.46 g/mol) as shown below:

[tex]n_{FeS}=50.0gHCl*\frac{1molHCl}{36.46gHCl}*\frac{1molFeS}{2molHCl}\\\\n_{FeS}=0.686molFeS \\\\\\m_{H_2S}=50.0gHCl*\frac{1molHCl}{36.46gHCl}*\frac{1molH_2S}{2molHCl}*\frac{34.04gH_2S}{1molH_2S} \\\\n_{H_2S}=23.3gH_2S[/tex]

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Answer:

Hope this helps! （；＿；)/

Explanation:

Answer:B

Explanation:

Maybe

Answer:B is correct

Explanation:

Answer:

See explanation

Explanation:

Let us have it behind our minds that the dielectric constant reveals the degree of polarity of a molecule. This implies that the more polar a molecule is, the greater its dielectric constant.

Chloroform is a polar molecule while carbon tetrachloride is a nonpolar molecule due to its symmetrical nature. Thus Chloroform has  a greater degree of polarity and consequently a higher dielectric constant.

Methanol is more polar than ethanol because polarity of the molecule decreases as more CH2s are added to the molecule, that is, polarity of the molecule decreases with increase in the length of the carbon chain. Since methanol is more polar than ethanol, it should have a greater dielectric constant.

Again, the presence of more akyl groups in acetone makes it less polar than formamide. Consequently, formamide has a greater dielectric constant than acetone.

Answer:

Concave Lenses Are for the Nearsighted, Convex for the Farsighted. Concave lenses are used in eyeglasses that correct nearsightedness.

Explanation:

The numbers inside the box represent the number of protons or atomic number while the circles represent the energy levels or shells in the atom. The dots represent the electrons occupying those shells.

The atomic number refers to the number of protons in the nucleus of an atom. It is shown as the number inside the boxes. It serves as the identity of an element.

The electrons occupy shells of particular energy levels according to Bohr model. The circles represent these energy levels. The dots in the circles represent the electrons that occupy those energy levels.

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The question is incomplete, the complete question is;

In a laboratory experiment, students synthesized a new compound and found that when 12.23 grams of the compound were dissolved to make 228.1 mL of a benzene solution, the osmotic pressure generated was 4.55 atm at 298 K. The compound was also found to be non-volatile and a non-electrolyte. What is the molecular weight they determined for this compound?

Answer:

287.76 g/mol

Explanation:

From;

π = M R T

M = molarity

R= gas constant

T = temperature

number of moles = π * volume/RT

number of moles = 4.55 * 228.1/1000/0.082 * 298

number of moles = 1.037855/24.436

number of moles = 0.0425 moles

Molar mass = mass/number of moles

Molar mass = 12.23 grams/0.0425 moles

Molar mass = 287.76 g/mol

Answer:

3rd

Explanation:

Answer: Ca(NO3)2(aq) + 2NaOH(aq) —> Ca(OH)2(s) + 2NaNO3(aq)

Substitution

Explanation:

The given reaction is a substitution reaction in which hydroxil group is exchanged between compounds.

Substitution Reaction:

It is a reaction in which functional group of a compound replaced by the another functional group.

For example-

[tex]\bold {Ca(NO3)_2(aq) + 2NaOH(aq) \rightarrow Ca(OH)_2(s) + 2NaNO_3(aq)}[/tex]

In the reaction hydroxil group is exchanged between compounds.

1 mole of aqueous calcium nitrate react with  2 moles aqueous sodium hydroxide to produce  1 mole of solid precipitate calcium hydroxide and 2 moles aqueous sodium nitrate.

Therefore, the given reaction is a substitution reaction in which hydroxil group is exchanged between compounds.

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Answer:

8 × 10³ mol N₂

Explanation:

Step 1: Write the balanced equation

2 C₃H₅N₃O₉ ⇒ 6 CO₂ + 5 H₂O + 0.5 O₂ + 3 N₂

Step 2: Convert the mass of C₃H₅N₃O₉ from tons to grams

We will use the conversion factor 1 t = 907185 g.

1.320 t × 907185 g/1 t = 1.197 × 10⁶ g

Step 3: Calculate the moles corresponding to 1.197 × 10⁶ g of C₃H₅N₃O₉

The molar mass of C₃H₅N₃O₉ is 227 g/mol.

1.197 × 10⁶ g × 1 mol/227 g = 5.27 × 10³ mol

Step 4: Calculate the moles of N₂ formed from 5.27 × 10³ moles of C₃H₅N₃O₉

The molar ratio of C₃H₅N₃O₉ to N₂ is 2:3.

5.27 × 10³ mol C₃H₅N₃O₉ × 3 mol N₂/2 mol C₃H₅N₃O₉ = 7.91 × 10³ mol N₂ ≈ 8 × 10³ mol N₂