PLS HELP!! Need help with this asap.

Answer:

I found on internet may be it helps

Explanation:

Here, we provide a general review of recent studies into the genetic basis of human brain evolution. The insights gleaned from these studies can be broadly divided into three categories: (i) positive selection on protein-coding regions of the genome that lead to changes in the sequences of existing proteins; (ii) duplication and deletion of genes; and (iii) evolutionary changes in non-coding regions of the genome, especially those in cis-regulatory sequences that lead to altered gene expression .

Answer: 2.5 moles

2H2 + O2 = 2H2O

This implies that 2 moles of oxygen is needed to react with one mole of oxygen to form 2 moles of water

It also implies that

2 moles of hydrogen requires 32 grams of oxygen

? moles of hydrogen would require 40 g of oxygen

2 x 40/32 = 2.5 moles

Answer:

15. 2.66 moles .

16. 2.09L.

Explanation:

Molarity of a solution is simply defined as the mole of solute per unit litre of the solvent. Mathematically, it is represented as:

Molarity = mole /Volume.

With the above formula, let us answer the questions given above

15. Data obtained from the question include the following:

Volume of solution = 1.4L

Molarity = 1.9M

Mole of solute =.?

Molarity = mole /Volume

1.9 = mole / 1.4

Cross multiply

Mole = 1.9 x 1.4

Mole = 2.66 moles

Therefore, the mole of the solute present in the solution is 2.66 moles.

16. Data obtained from the question include the following:

Mole of solute = 0.46 mole

Molarity = 0.22M

Volume of solvent (water) =.?

Molarity = mole /Volume

0.22 = 0.46/Volume

Cross multiply

0.22 x Volume = 0.46

Divide both side 0.22

Volume = 0.46/0.22

Volume = 2.09L

Therefore, 2.09L of water is required.

Answer:

molar mass of C₃H ₈ = 44 g/mole

Explanation:

Computation of the amount of oxygen that reacts .

⇒ 75 - 12.5

⇒ 62.5 cm³

Computation of  proportion of hydrocarbons

2 mole hydrocarbons 3n+1 oxygen

⇒ 3 n + 1 = [62.5 × 2] / 12.5

⇒ 3 n + 1 = 10

⇒ n = 3

So,

Formula of the hydrocarbon is C₃H ₈

Computation of molar mass of C₃H ₈

⇒ [12×3] + [1×8]

⇒ 44 g/mole

Answer:

CaCO3 + 2HCl = CaCl2 + CO2 + H2O

Explanation:

CaCO3 + HCl = CaCl2 + CO2 + H2O

Error in equation should be HCl on left hand side not HC

Left Side

Ca = 1

C = 1

O = 3

H = 1

Cl = 1

Right Side

Ca = 1

C = 1

O = 3

H = 2

Cl = 2

So we'll try and balance the Chlorine

CaCO3 + 2HCl = CaCl2 + CO2 + H2O

Left Side

Ca = 1

C = 1

O = 3

H = 2

Cl = 2

Right Side

Ca = 1

C = 1

O = 3

H = 2

Cl = 2

Yay it worked

Answer:

b

Explanation:

i got it right on edge

To balance a reaction means to make the number of atoms the same on both the reactants and products side. The steps for balancing is as follows:-

According to the question, there are third reactions. the reaction third has the 3 coefficient before the compound.

The balanced reaction is as follows:-

[tex]3H_2So_4 + 2B (OH)_3------->B_2(So_4)_3 + 6H_2O[/tex]

Hence the correct compound is[tex]3H_2SO_4[/tex].

For more information, refer to the link:-

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Answer:

Percent Yield = 91.97%

Explanation:

Aluminum hydroxide Formula: Al(OH)3 Molar mass: 78 g/mol

Stomach acid Formula: HCl Molar mass: 36.46 g/mol

Aluminum Chloride Formula: AlCl₃ Molar mass: 133.34 g/mol

14g Al(OH)3

2Al(OH)3 + Cl2 → 2Al(OH)3Cl

Balanced equation

14/156 = 0.0897 Moles of Al(OH)3

Ratio is 2:1:2 so same ratio for Al(OH)3 to AlCl₃

0.0897 x 266.68 = 23.92grams of AlCl₃

Theoretical yield of aluminum chloride

Actual yield aluminum chloride 22.0 g

Percent yield?

Percent Yield = (actual Yield/Theoretical yield) x 100

Percent Yield = (22/23.92) x 100

Percent Yield = 91.97%

The percent yield of aluminum chloride in the neutralization reaction has been 91.97%.

The balanced reaction for neutralization of stomach acid with aluminum hydroxide has been:

[tex]\rm Al(OH)_3\;+\;3\;HC\l\rightarrow\;AlCl_3\;+\;3\;H_2O[/tex]

The reaction has been determined that 1 mole of aluminum hydroxide forms 1 mole of aluminum chloride. The moles of aluminum hydroxide has been given as:

Moles =  [tex]\rm \dfrac{Mass}{Molecular\;mass}[/tex]

Moles of Aluminum hydroxide = [tex]\rm \dfrac{14}{156}[/tex]

Moles of Aluminum hydroxide = 0.0897 mol.

Thus, the aluminum chloride formed has been:

1 mole Aluminum hydroxide = 1 mole aluminum chloride

0.0897 mole aluminum hydroxide = 0.0897 mole aluminum chloride

The mass of Aluminum chloride formed has been:

0.0897 mole aluminum chloride = [tex]\rm \dfrac{Mass}{266.68}[/tex]

Mass of Aluminum chloride = 0.0897 mol × 266.68 g/mol

Mass of Aluminum chloride = 23.92 grams

The %yield can be given as:

%Yield = [tex]\rm \dfrac{Actual\;yield}{Theoretical\;yield}\;\times\;100[/tex]

The theoretical yield = 23.92 grams

The actual yield = 22 grams

% Yield = [tex]\rm \dfrac{22}{23.92}\;\times\;100[/tex]

% Yield = 91.97%.

The percent yield of aluminum chloride in the neutralization reaction has been 91.97%.

For more information about the neutralization reaction, refer to the link:

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Answer:

d Rubidium

Explanation:

The atomic radius of an atom is the distance from the center of the nucleus to its outermost electron.

The atomic radius of elements varies in the periodic table, it increases as you go down in a group and decreases along the period from left to right.  

All the elements listed: Hydrogen, Sodium, Lithium and Rubidium belong to the same group in the periodic table (group 1), Since atomic radius increases from top to bottom in a group, Rubidium has the largest atomic radius.

Answer:

Foliation is developed by stress and fire while layering is developed by the embedding of fine and coarse deposits. Foliation is caused due to an alteration of minerals from pressure and heat while layering is developed by seasonal changes

Explanation:

Banding occurs when two different mineral compositions alternate in thin layers (typically 1 mm to 1 cm). The two types of layers typically contain the same minerals, but in different proportions, giving the rock a striped appearance. A foliation is defined by its banding.

To learn more about foliation, refer to:

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#SPJ2

Answer:

The HWA attacks eastern hemlock trees in forests and ornamental hemlock trees found in our residential landscaping. It feeds on the hemlock trees' young twigs by sucking the sap, causing their buds to die and needles to dry out and drop from the plant prematurely i think

hope i helped!!

Answer:

Not sure what the answer is

Explanation:

I did this a while ago and dont remember sorry

Answer:

11 grams

Explanation:

Answer:

A. formation of snow

Explanation:

The formation of snow is an example of interactions between the atmosphere and hydrosphere.

As snow formation takes place when water vapor converted into liquid through condensation in the clouds. As water droplets rises high in clouds, cooler air present in atmosphere allow to lower the temperature and water droplets form ice or snow.

Hence, the correct option is A.

Answer:

A:formation of snow

Explanation:

Answer:

Energy, [tex]E=5.3\times 10^{-21}\ J[/tex]

Explanation:

It is required to find the energy of an electromagnetic wave with a frequency of [tex]8\times 10^{12}\ Hz[/tex]. The energy of a wave in terms of its frequency is given by :

[tex]E=h\nu[/tex]

[tex]\nu[/tex] = frequency of em wave

[tex]E=6.63\times 10^{-34}\times 8\times 10^{12}\\\\E=5.3\times 10^{-21}\ J[/tex]

So, the energy of an electromagnetic wave is [tex]5.3\times 10^{-21}\ J[/tex]

Answer:

D. [tex]5.3 * 10^-21 J[/tex]

Answer:

Oxygen

Explanation:

A glowing splint applied to a sample of gas "oxygen" will relight.

Answer:

-4

Explanation:

[tex]log 10^{-4} = -4 log 10[/tex]

log 10 = 1

Therefore -4 log 10 = -4 x 1 = -4

Answer:

they move faster

Explanation:

Answer:

They move faster.

Answer:

Potential energy is the amount of energy calculated from an object's height off the ground.

Explanation:

Potential energy = Mass x Height x Gravity

Answer:

Water H2O

Explanation:

A solvent is defined as being able to dissolve other substances, the fertilizer is being dissolved in the water prior to watering the plants, therefore the water is the solvent in this case.

Answer: thats alot of reading

Explanation:

Answer:

it causes alot of harm to the earth.

Explanation:

earthquakes

an so on

Answer:

           1s², 2s², 2p³  

Explanation:

The atomic number of Nitrogen is seven. So it contains seven protons and seven electrons in neutral form. Also, the electronic configuration cited above contains seven electrons among which two electrons are present in first shell and five electrons are present in valence shell respectively.

Answer: E. 78%

Explanation:

Diborane (B2H6), a chemical compound made up of approximately 78% Boron and 22% Hydrogen.

Answer:

E

Explanation:

#edmentumgang

Answer:

None of them, answer seems to be 24 unless I messed up

Explanation:

How many electrons appear in the balanced equation

What the heck do they mean, do they mean transferred?

N2O5 --> NH4+

Left Side

N 5+  Electrons 2 in central shell, 5 in outer

O 2- Electrons 2 in central shell, 6 in outer

Right Side

H  1+ Electrons 1 in central shell

N 3- Electrons 2 in central shell, 5 in outer

Hmm, ok so need to balance the half equation first, this is a redox reaction.

Hmm, so it's going to be something like

H2 + N2O5 → NH + O3  

Step 1. Write down the unbalanced equation ('skeleton equation') of the chemical reaction. All reactants and products must be known. For a better result write the reaction in ionic form.

H2 + N2O5 → NH + O3  

Step 2. Separate the process into half reactions. A redox reaction is nothing but both oxidation and reduction reactions taking place simultaneously.

a) Assign oxidation numbers for each atom in the equation. Oxidation number (also called oxidation state) is a measure of the degree of oxidation of an atom in a substance (see: Rules for assigning oxidation numbers).

H02 + N+52O-25 → N-1H+1 + O03  

b) Identify and write out all redox couples in reaction. Identify which reactants are being oxidized (the oxidation number increases when it reacts) and which are being reduced (the oxidation number goes down). Write down the transfer of electrons. Carefully, insert coefficients, if necessary, to make the numbers of oxidized and reduced atoms equal on the two sides of each redox couples.

When one member of the redox couple is oxygen with an oxidation state of -2 or hydrogen with an oxidation state of +1, it is best to replace it with a water molecule.

O:3H+12O-2 → O03 + 6e-(O)

H02 → H+12O-2 + 2e-(H)

R:N+52O-25 + 12e- → 2N-1H+1(N)

c) Combine these redox couples into two half-reactions: one for the oxidation, and one for the reduction (see: Divide the redox reaction into two half-reactions).

O:3H+12O-2 + H02 → O03 + H+12O-2 + 8e-  

R:N+52O-25 + 12e- → 2N-1H+1  

Step 3. Balance the atoms in each half reaction. A chemical equation must have the same number of atoms of each element on both sides of the equation. Add appropriate coefficients (stoichiometric coefficients) in front of the chemical formulas to balance the number of atoms. Never change any formulas.

a) Balance all other atoms except hydrogen and oxygen. We can use any of the species that appear in the skeleton equations for this purpose. Keep in mind that reactants should be added only to the left side of the equation and products to the right.

O:3H+12O-2 + H02 → O03 + H+12O-2 + 8e-  

R:N+52O-25 + 12e- → 2N-1H+1  

b) Balance the charge. For reactions in an acidic solution, balance the charge so that both sides have the same total charge by adding a H+ ion to the side deficient in positive charge.

O:3H+12O-2 + H02 → O03 + H+12O-2 + 8e- + 8H+  

R:N+52O-25 + 12e- + 12H+ → 2N-1H+1  

c) Balance the oxygen atoms. Check if there are the same numbers of oxygen atoms on the left and right side, if they aren't equilibrate these atoms by adding water molecules.

O:3H+12O-2 + H02 + H2O → O03 + H+12O-2 + 8e- + 8H+  

R:N+52O-25 + 12e- + 12H+ → 2N-1H+1 + 5H2O  

Balanced half-reactions are well tabulated in handbooks and on the web in a 'Tables of standard electrode potentials'. These tables, by convention, contain the half-cell potentials for reduction. To make the oxidation reaction, simply reverse the reduction reaction and change the sign on the E1/2 value.

Step 4. Make electron gain equivalent to electron lost. The electrons lost in the oxidation half-reaction must be equal the electrons gained in the reduction half-reaction. To make the two equal, multiply the coefficients of all species by integers producing the lowest common multiple between the half-reactions.

O:3H+12O-2 + H02 + H2O → O03 + H+12O-2 + 8e- + 8H+| *3

R:N+52O-25 + 12e- + 12H+ → 2N-1H+1 + 5H2O| *2

O:9H+12O-2 + 3H02 + 3H2O → 3O03 + 3H+12O-2 + 24e- + 24H+  

R:2N+52O-25 + 24e- + 24H+ → 4N-1H+1 + 10H2O  

Step 5. Add the half-reactions together. The two half-reactions can be combined just like two algebraic equations, with the arrow serving as the equals sign. Recombine the two half-reactions by adding all the reactants together on one side and all of the products together on the other side.

9H+12O-2 + 2N+52O-25 + 3H02 + 24e- + 3H2O + 24H+ → 3O03 + 4N-1H+1 + 13H2O + 24e- + 24H+

Step 6. Simplify the equation. The same species on opposite sides of the arrow can be canceled. Write the equation so that the coefficients are the smallest set of integers possible.

2N+52O-25 + 3H02 → 3O03 + 4N-1H+1 + H2O

Answer:

The answer to your question is given below

Explanation:

1. Data obtained from the question include:

Hydrogen ion concentration, [H+] = 1x10^-9M

pH =..?

pH = - log [H+]

pH = - log 1x10^-9

pH = 9

2. Data obtained from the question include:

pOH = 3

pH =.?

Recall:

pH + pOH = 14

pH + 3 = 14

Collect like terms

pH = 14 - 3

pH = 11

3. Data obtained from the question include:

Hydroxide ion concentration, [OH-] = 1x10^-2M

pH =..?

First, we shall determine the pOH. This is illustrated below

pOH = - Log [OH-]

pOH = - Log 1x10^-2

pOH = 2

Finally, we can obtain the pH as follow:

pH + pOH = 14

pOH = 2

pH + 2 = 14

Collect like terms

pH = 14 - 2

pH = 12

4. Data obtained from the question include:

pOH = 7

pH =.?

Recall:

pH + pOH = 14

pH + 7 = 14

Collect like terms

pH = 14 - 7

pH = 7

Answer:

D.

Explanation:

CH₃C≡ CCH₂CH₂Cl

Since there are 5 carbons so the suffix used is "pent"

There is a triple bond so its alkyne

So the compound becomes 2-pentyne (2 because the triple bond is with the 2nd carbon)

Then,

The functional group of chlorine is attached with 5th carbon So the compound becomes

5-chloro,2-pentyne

Answer:

C. Stir rapidly

Answer:

If the reaction is going from left to right it would be synthesis, if going right to left it would be decomposition.

Explanation:

Na2O (s) + 2CO2 (g) + H2O (g) = 2 NaHCO3 (s)

Left Side

Na = 2

O = 6

C = 2

H = 2

Right Side

Na = 2

O = 6

C = 2

H = 2

Ok so is balanced already, though initial equation in question had an error in regards to the left hand side the ) should have been an O.

Hmm

Na2O (s) + 2CO2 (g) + H2O (g) = 2 NaHCO3 (s)

If it was going from right to left would be decomposition

But going from left to right it would be synthesis

Answer:

0 C.

Explanation: