Science...............

Answer:

1.61 x 10²⁰ molecules

Explanation:

Given parameters:

Mass of the hydrogen gas  = 8.01 x 10⁻⁴g

Unknown

Number of molecules of NH₃ = ?

Solution:

Given reaction:

                     N₂  +  3H₂   →   2NH₃

We have to solve from the known to the unknown

             find the number of moles of the specie;

    number of moles = [tex]\frac{mass}{molar mass}[/tex]

     Molar mass of H₂ = 2(1) = 2g/mol

   Number of moles  = [tex]\frac{0.0008}{2}[/tex]   = 0.0004mol

      0.0004 moles of H₂ will produce [tex]\frac{0.0004 x 2}{3}[/tex]   = 0.00027moles of NH₃

   1 mole of a substance contains 6.02 x 10²³ molecules

     0.00027mole of NH₃ will contain 0.00027 x 6.02 x 10²³

                               = 1.61 x 10²⁰ molecules

Answer:

no d

Explanation:

it has a permanent dipole

CH₃F compound contains polar covalent bonds in its structure, hence option D is correct.

This happens when the electronegativity of the relevant atoms differs significantly.

The electronegativities of the carbon and fluorine atoms in CH3F are dissimilar. Because fluorine is more electronegative than carbon, it attracts the shared electrons to it, giving the fluorine atom a partial negative charge and the carbon atom a partial positive charge.

A polar covalent bond is created as a result of this unequal charge distribution. CH₃F compound contains polar covalent bonds in its structure.

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Answer:

NH₂O

Explanation:

Given compound:

       N₄H₈O₄

Unknown:

The empirical formula of the compound  = ?

Solution:

The empirical formula of a compound is its simplest formula. It expresses the composition of a the compound in the simplest whole ratio of atoms of the different elements present in the compound.

 For the given compound:

                                  N₄H₈O₄

  Number of moles of N = 4

                                      H = 8

                                      O = 4

 the highest common factor is 4 and we simply divide through by this number;

                                      N = 1

                                      H = 2

                                      O = 1

So, the empirical formula of compound is NH₂O

Dull black surface are good absorbers of radiation.

The process by which energy in the form of electromagnetic radiation is emitted by a heated surface and travels directly to its absorption point at the speed of light.

The rate at which a body absorbs or radiates thermal radiation relies upon the nature of the surface as well.

According to the Kirchhoff's radiation law, the objects, which are good emitters are also good absorbers.

A blackened surface is an excellent absorber as well as an excellent emitter.

A black body refers to a body, which is regarded as a perfect radiator and absorber of electromagnetic radiations, a dull black surface is a good absorber of heat radiation.

Thus, dull black surface is the best surface for absorbing heat radiation.

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Answer:

Percent error

Explanation:

Percent error is defined as the percentage of the difference between the measured( accurate value) and the known value of a substance.

It is usually calculated by:

Measured value — Known value/ known value * 100%

Percent error is the calculated value that is used to evaluate accuracy for a set of data

Answer:

Oxygen is used up

Explanation:

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Answer:

Covalent bond involves the sharing of electrons, while metallic bonds have strong attractions and ionic bonds involve the transferring and accepting of electrons from the valence shell. The adhering property of an atom, in order to arrange themselves in a most stable pattern by filling their outermost electrons orbit

Explanation:

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Answer:

Explanation:

pituitary gland

Answer:

B

Explanation:

The pituitary gland is a pea-sized structure that is attached to the undersurface of the brain by a thin stalk.

Answer:

5;11

Explanation:

Answer:

C) Reactants absorb a minimum amount of energy and then release a smaller  

amount of energy as products form.

Explanation:

The statement that best describes how to read a reaction pathway from the graph of an endothermic reaction is that, reactants absorb a minimum amount of energy and then release a smaller amount of energy as products form.

In an endothermic change, heat is absorbed from the surrounding.

Answer: B

Explanation: a calcium ion has a charge of +2 because it has 2 more protons than electrons giving it a positive charge instead of neutral or negative.

Answer:

False

Explanation:

From the question given above, the following data were obtained:

Electron number = 6

Proton number = 6

Neutron number = 6

From the question given above, we can see clearly that the model has the same number of protons and electrons. Hence the model is not an ion.

This can further be explained if we determine the charge.

Electron number = 6

Proton number = 6

Charge =?

Charge = Proton – Electron

Charge = 6 – 6

Charge = 0

Since the charge is zero, the model is not an ion.

Answer:

NaCl(aq)

Explanation:

Nacl(aq) is an electrolyte when it melts and it conducts electricity. This is due to the fact that when it is in solution, it dissociates to be Na+ and Cl-. These ions are conductors of electricity. It conducts electricity because of the movements and also the discharge of ions. CH3OH(aq) is not a conductor of electricity therefore the first option is the answer.

Answer:

a. 0.183 mol C

b. 0.366 mol H

Explanation:

Assuming total combustion, all of the carbon in the unknown compound turned into carbon dioxide, CO₂.

So first we calculate the CO₂ moles produced, using its molecular weight:

This means in the unknown compound there were 0.183 moles of carbon, C.

Conversely, all of the hydrogen in the unknown compound turned into water, H₂O.

Calculating the H₂O moles:

We multiply the water moles by two, as there are 2 H moles per H₂O mol:

Answer:

Silver.

Explanation:

Hello!

In this case, we can consider the specific heat as the property that we can analyze in order to answer to this question. In such a way, as the specific heat is known as the energy required to modify the temperature of 1 g of the substance by 1 °C, since the masses of all the substances are the same, we can that their specific heats are respectively 0.240, 0.444 and 4.184 J/(g°C), from the equation:

[tex]Q=mCp\Delta T[/tex]

We can see that the higher the specific heat (Cp) the lower the change in temperature considering their inversely proportional relationship. However, as 100 J of energy is applied to all the substances, we can see that silver will exhibit the largest temperature change because a higher change is needed to fit with the provided energy.

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Answer:

Kc = 4.86×10⁻⁶

Explanation:

We begin from the equation:

N₂  +  2H₂ ⇄  2NH₃

We start from 3.47×10⁻² moles of N₂(g) and 6.38×10⁻² moles of H₂(g), so when we reach the equilibrium, we get 6.25×10⁻² moles of H₂.

This data means, that in the reaction we made react:

6.38×10⁻² - x = 6.25×10⁻²

x = 1.3×10⁻³ moles of H₂

As stoichiometry is 1:3, we will know that the moles of N₂ that have been reacted were:

1.3×10⁻³ moles / 3 = 4.33×10⁻⁴ moles of N₂

So, in the equilibrium we would have:

3.47×10⁻² moles of N₂ - 4.33×10⁻⁴ moles of N₂ = 0.0343 moles of N₂

How many ammonia, would we have in the equilibrium?

4.33×10⁻⁴ mol . 2 = 8.66×10⁻⁴ moles (from stoichiometry with N₂, 1:2)

(1.3×10⁻³ mol . 2) / 3 = 8.66×10⁻⁴ moles (from stoichiometry with H₂, 2:3)

Let's make the expression for Kc

Kc = [NH₃]³ / [N₂] . [H₂]²

(8.66×10⁻⁴ )³ / (0.0343 . (6.25×10⁻²)² = 4.86×10⁻⁶

Answer:

Explanation:

Al(s) + 3/2 Br₂(l) = AlBr₃(s)

K = [  AlBr₃] / [ Al] [  Br₂]³/²

K² =  [  AlBr₃]² / [  Al ] ² [ Br₂]³

2 AlBr₃ = 2 Al(s) + 3 Br₂(l) =

K₁ =  [  Al ] ² [ Br₂]³ /  [  AlBr₃]²

K₁ =  ( 1 / K² ) = K⁻²

2 ) 2 Al(s) + 3 Br₂(l) = 2 AlBr₃(s)

K₂ = [ AlBr₃ ]² / [  Al ]² [  Br₂ ]³

K₂ = K²

3 )

AlBr₃(s) =   Al(s) + 3/2 Br₂(l)

K₃  = [ Al ] [ Br₂ ] ³/² / [ AlBr₃ ]

=  ( 1 / K ) = K⁻¹

Answer:

Explanation:

Significant figure implies number of digits that are to be considered. Some rules are required to be considered when writing a given expression to an expected significant figures.

So that:

1) 0.00004050 is 4 significant figures

2) 54.7000 is 6 significant figures

3) 1,000.09 is 6 significant figures

4) 0.039 is 2 significant figures

Answer:

4

Explanation:

24/6 is 4.

Answer:

Mathematically: D = m/v. If you know what liquid you have, you can look up its density in a table. Once you know that, all you have to do to find the mass of the liquid is to measure its volume. Once you know density and volume, calculate mass using this relationship: mass = density • volume.

Explanation:

Answer:

The plant uses carbon dioxide and water to make an entirely new chemical hence chemical change.

Explanation:

Plants create their own 'food', they turn carbon dioxide water and sunlight to create starch and glucose..

Answer:

The properties of carbon dioxide and oxygen are different.

Explanation:

im taking the exam right now and Im pretty sure it's D The properties of carbon dioxide and oxygen are different.

Answer:

2.75 g

Explanation:

The number of moles of KOH is obtained from the equation;

n=CV

C= concentration

V= volume of solution

n= 0.527 × 25.6/1000

n= 0.0135

Reaction equation;

KOH(aq) + KHC8H4O4(aq) --->(KC8H4O4)K(aq) + H2O(l)

1 mole of KHP reacts with 1 mole of KOH

Hence; 0.0135 moles of KHP reacts with 0.0135 moles of KOH

From;

Number of moles = reacting mass/molar mass

Reacting mass = 0.0135 × 204

= 2.75 g of KHP

Answer:

2 C 2 H 2 ( g ) + 5 O 2 ( g ) ⟶ 4 C O 2 ( g ) + 2 H 2 O ( l )- combustion reaction

N H 4 N O 3 ( s ) ⟶ N 2 O ( g ) + 2 H 2 O ( l )- decomposition reaction

C O ( g ) + 2 H 2 ( g ) ⟶ C H 3 O H ( l ) - combination reaction

2 F e ( s ) + 6 H C l ( a q ) ⟶ 2 F e C l 3 ( a q ) + 3 H 2 ( g )- Redox reaction

C a C l 2 ( a q ) + N a 2 C O 3 ( a q ) ⟶ 2 N a C l ( a q ) + C a C O 3 ( s )- double displacement reaction

Explanation:

We can determine the type of reaction by considering the reactants and products.

Combustion is a reaction between a substance and oxygen which produces heat and light. The first reaction is the equation for the combustion of ethyne.

A decomposition reaction is one in which a single reactant breaks down to form products. The second reaction is the decomposition of ammonium nitrate.

A  combination reaction is said to occur when two elements or compounds react to form a single product. The third reaction is the combination of carbon dioxide and methane to form  methanol.

An oxidation-reduction reaction is a reaction in which there is a change in oxidation number of species from left to right of the chemical reaction equation. The fourth reaction is the oxidation of iron (0 to +3 state) and reduction of hydrogen (+1 to 0 state).

A double displacement reaction is a reaction in which ions exchange partners from left to right in the reaction equation. The fifth reaction is a double displacement reaction. Both Na^+ and Ca^2+ exchanged partners from left to right of the reaction equation.

Reactions are the formation of the products from the reactant. The types of reactions are combustion, decomposition, combination, Redox and double displacement.

The reaction is a chemical change in the properties of the reactant that forms the products. It can be of various types based on the formation of the product.

The first reaction is combustion as the reactants react and use oxygen to form heat, carbon dioxide and water. The combustion reaction of ethyne can be shown as,

[tex]\rm 2 C _{2} H _{2} ( g ) + 5 O _{2} ( g ) \rightarrow 4 C O _{2} ( g ) + 2 H _{2} O ( l )[/tex]

The second reaction is decomposition in which a single reactant decomposes to form two or more products. The decomposition of ammonium nitrate can be shown as,

[tex]\rm N H _{4} N O _{3} ( s ) \rightarrow N _{2} O ( g ) + 2 H _{2} O ( l )[/tex]

The third reaction is a combination reaction in which two compound or elements combines to form one product. The combination reaction between carbon monoxide and hydrogen to form methanol can be shown as,

[tex]\rm C O ( g ) + 2 H _{2} ( g ) \rightarrow C H _{3} O H ( l )[/tex]

The fourth reaction is redox and includes the oxidation and the reduction of the species of the reaction. In the reaction, iron undergoes oxidation and hydrogen reduction. The redox reaction can be shown as,

[tex]\rm 2 F e ( s ) + 6 H C l ( a q ) \rightarrow 2 F e C l _{3} ( a q ) + 3 H _{2} ( g )[/tex]

The fifth reaction is a double displacement reaction in which the calcium and sodium interchange their position in the product formation. The reaction can be shown as,

[tex]\rm C a C l _{2} ( a q ) + N a _{2} C O _{3} ( a q ) \rightarrow 2 N a C l ( a q ) + C a C O _{3} ( s )[/tex]

Therefore, the type of reactions is 1. combustion, 2. decomposition, 3. combination, 4. redox and 5. double displacement.

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Answer:

Ecological islands is just a terminology used, since it isn't surrounded by water like an actual island, instead, it's something isolated from other things, which is the same thing as an island in a way:

Island (geographical) - Land isolated from bigger "main" land masses by water.

Island (ecological) - Land which contains certain isolated features (habitat, plants, etc.).

Explanation:

An ecological island is an area of land, isolated by natural or artificial means from its surrounding land while geographical islands are a body of land surrounded by water.

An ecological island refers to an area of land which is not necessarily an actual island but isolated by natural or artificial means from the surrounding land. A natural micro-habitat exists on sich lands amidst a larger differing ecosystem.

In artificial ecological islands, all non-native species are eradicated, native species are reintroduced and nurtured, and the natural or artificial border is maintained to prevent the reintroduction of non-native species.

A geographical island is a body of land surrounded by water. Continents are also surrounded by water as they are so big but they are not considered islands. Islands may be categorized as either continental or oceanic.

There are so many islands in the lakes, oceans, and rivers around the world. They vary in climate, size, and the types of organisms that inhabit them.

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Answer:

You feel warm when you stand near a campfire because the flames of the fire warm your body. The heated waves are hit towards you and your body feels warm.

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Explanation:

Answer:

[tex]a=\frac{f}{d-e}-\frac{b}{c}[/tex]

Explanation:

Hello.

In this case, for the equation:

[tex](a+b/c)(d-e)=f[/tex]

For isolating a, we must first pass (d-e) to divide at the other side as it is initially multiplying:

[tex]a+b/c=\frac{f}{(d-e)}[/tex]

Next, as b/c is adding, it passes to subtract at the other side in order to finally isolate a:

[tex]a=\frac{f}{d-e}-\frac{b}{c}[/tex]

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Answer: The mass of blue copper sulfate is 3.5 g

Explanation:

Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.

This also means that total mass on the reactant side must be equal to the total mass on the product side.

The chemical equation for the heating of copper sulfate crystals is:

Let the mass of blue copper sulfate be 'x' grams

We are given:

Mass of copper sulfate powder = 2.1 grams

Mass of water = 1.4 grams

Total mass on reactant side = x

Total mass on product side = (2.1 + 1.4) g

So, by applying law of conservation of mass, we get:

Hence, the mass of blue copper sulfate is 3.5 grams