11.
In the 1930s, how did Dobzhansky and Mayr explain the origin of species?

Species originate due to gradual adaptations to the environment.

Species originate from interbreeding.

Species originate through allopatric speciation.

Species originate due to behavioral changes.

Answer:

= 6.56 × 10²⁴ ions

Explanation:

We are given;

10.9 moles of Iron (iron doesn't exists as a molecules, so we can't have 10.9 molecules but we can have 10.9 moles)

We are required to determine the number of ions

We need to know that;

1 mole of iron = 6.022 × 10²³ ions

Therefore;

10.9 moles of iron will contain;

= 10.9 moles × 6.022 × 10²³ ions/mol

= 6.56 × 10²⁴ ions

Hence, 10.9 moles of iron contains 6.56 × 10²⁴ ions

Answer:

dioxide

Explanation:

Answer:

4 moles

Explanation:

N is 1 atom and H has a subscript of 3 meaning there are 3 hydrogen atoms. (3+1=4). We know that N is a separate element of H, because they are both uppercase.

Moles are defined as the smallest base unit that is equivalent to [tex]6 .02214 \times 10^{23}[/tex] units.

In the given molecule of NH[tex]_4[/tex], there will be 4 moles of each atom.

NH[tex]_4[/tex] consists of 1 mole of the Nitrogen atom and 3 moles of the Hydrogen atom, which is then equivalent to the 4 moles of each atom in the molecule of NH[tex]_4[/tex].

Moles are chemical entities, which are used to measure the mass or molecular mass of the compound, molecule, or atom. The moles are, for example can be explained as equal to the mass of the atom. For example, there is one mole in 12 grams of carbon.

Thus, the correct answer is Option D.

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Answer:

Moles of NaCl formed is 6.0 moles

Explanation:

We are given the equation;

2 Na(s) + Cl₂(g) → 2 NaCl(s)

From the reaction;

2 moles of sodium reacts with 1 mole of chlorine gas to form 2 moles of NaCl

In this case;

6 moles of Na would require 3 moles of Cl₂, this means that chlorine gas is in excess.

Thus, the rate limiting reagent is sodium.

But, 2 moles of sodium reacts to form 2 moles of NaCl

Therefore;

Moles of NaCl = Moles of Na

                      = 6.0 moles

Thus, moles of sodium chloride produced is 6.0 moles

Answer:

The periodic table

Explanation:

The periodic table can show the atomic number and atomic mass of any atoms easily. To convert grams of water to moles of water, you need to know the atoms that made up water molecules then find out their molecular mass. Water is made of two hydrogens and one oxygen atoms. Then you can find the atomic mass of hydrogens is 1 while oxygen is 16. The molecular mass of water will be 2*1 + 16= 18g/mol.

Use the molecular weight of water as a conversion factor to convert grams to moles. Then, use the number of moles and the mass of solvent to determine the molality of the solution.

The most useful scientific tool when trying to convert a known amount of grams of water to moles of water is the molecular weight of water, which is used as a conversion factor. The process involves converting from grams to moles using the molecular weight of water (18.01528 g/mol).

In general, a mole of any substance has a mass in grams numerically equal to its molecular mass. So the molecular weight is a very convenient conversion factor for such calculations.

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The pressure of helium gas in the given condition is 948.45 mm of Hg.

Explanation:

As per ideal gas law, the product of pressure and volume will be equal to the product of number of moles, gas constant and temperature of gas molecules. This is formed by the combination of three basic laws of kinetic theory of gases.

[tex]PV = nRT[/tex]

As the pressure P is unknown, but the volume V, temperature T and number of moles n is given for helium gas.

R = 8.314 J mol⁻¹ K⁻¹ = 62.363 mmHg L mol⁻¹ K⁻¹.

Then, pressure can be found as

[tex]P = \frac{nRT}{V}[/tex]

As T = 50°C = 50 + 273 K = 323 K and volume V = 223 mL = 0.223 L and n = 0.0105 mol

Then, [tex]P = \frac{0.0105*62.363*323}{0.223}=948.45 mm of Hg[/tex]

So, the pressure of helium gas in the given condition is 948.45 mm of Hg.

A mixture is a substance made by combining two or more different materials in such a way that no chemical reaction occurs.

A mixture can usually be separated back into its original components. Some examples of mixtures are a tossed salad, salt water and a mixed bag of M&M's candy.

Explanation:If the mass of the object stays the same but the volume of the object decreases then its density becomes greater. If the volume of the object stays the same but the mass of the object increases then its density becomes greater.

Answer: 960 degrees celsius

Explanation:

The freezing point of silver is 960 degrees Celsius.

The melting point and freezing point of a pure substance are the same temperature, just described from different states of matter. When a substance transitions from solid to liquid, it is melting, and the temperature at which this occurs is called the melting point. Conversely, when a substance transitions from liquid to solid, it is freezing, and the temperature at which this occurs is called the freezing point. For silver, the temperature at which it melts (melting point) is 960 degrees Celsius, and this is also the temperature at which it freezes (freezing point). The value given for the freezing point in the question, 2162 degrees Celsius, is incorrect and is likely a typographical error. The correct freezing point of silver is 960 degrees Celsius.

Answer:

At high temperature and pressure, reactions become faster

Explanation:

Collision theory or reaction particle model state that reacting particles must collide before reactions occur.

Reaction rate of reaction is dependent on the frequency of collision.

Kinetics of gases increases at higher temperature and pressure.

As the temperature and pressure of nitrogen and oxygen increased, they bound to move more faster, collide more frequently as to attain activation energy easily thereby increasing the reaction rate or making the reaction to complete faster.

Also at higher pressure, gaseous reactants are closer to each other.

Answer:

a. pH paper can tell you the pH. pH paper only can turn a variety of colors that represent different pH numbers.

B. Litmus paper only tells you acid or base in order to turns red or blue color.

Explanation:

pH paper is a type of paper which is used for the identification of pH of the substance. On pH paper, colors are present which shows pH numbers of a solution while litmus paper is a type of paper which is used for the identification of solution whether it is acidic or basic. There are two colors i. e. Red and Blue. If the litmus paper turns red, the solution is acidic or if the litmus paper turns blue, the solution is alkaline or basic.

Answer:

15 moles of  ammonium sulfate would be formed from 30 moles of ammonia.

Explanation:

Given data:

Number of moles of ammonium sulfate formed = ?

Number of moles of ammonia = 30.0 mol

Solution:

Chemical equation:

2NH₃  +   H₂SO₄  →  (NH₄)₂SO₄

Now we will compare the moles of ammonium sulfate with ammonia.

                           NH₃           :           (NH₄)₂SO₄

                             2              :               1

                            30.0          :              1/2×30.0 = 15.0 mol

So 15 moles of  ammonium sulfate would be formed from 30 moles of ammonia.

Answer:

Explanation:

1. Write the balanced molecular equation(given):

Notice that I replaced Fe(NO₃)₂ with Ca(NO₃)2 because Fe does not appear in the products.

2. Write the aqueous ionic compounds in form of ions:

3. Write the overall ionic equation

In the balanced molecular molecular equation, substitute the ionic compounds with the corresponding ions:

Ca²⁺(aq) + 2NO₃⁻(aq) + 2Na⁺ (aq) + CO₃²⁻(aq) →

                                                         CaCO₃(s) + 2NO₃⁻(aq) + 2Na⁺(aq)

4. Write the net ionic equation

Remove the spectator ions (those that appear equal on both sides):

Answer:

The mass percent of a solution of 7.6 grams sucrose in 83.4 grams of water is 8.351 %.

Explanation:

Given,

Mass of Sucrose = 7.6 grams

Mass of Water = 83.4 grams

In this solution, Sucrose is solute and water is the solvent.

Mass percent of a solution can be calculated using the formula,

Mass percent =  (Mass of Solute/Mass of Solution)(100)

As sucrose is solute, mass of solute = 7.6 grams

As the solution contains both Sucrose and Water,

Mass of solution = 7.6 grams + 83.4 grams = 91 grams

Substituting the values, Mass percent = (7.6/91)(100) = 8.351 %.

Taking into account the definition of percentage by mass, the mass percent of a solution of 7.6 grams sucrose in 83.4 grams of water is 8.35 %.

The percentage by mass expresses the concentration and is defined as the ratio of the mass of the solute to the mass of the solution, expressed as a percentage.

The percentage by mass is calculated as the mass of the solute divided by the mass of the solution and multiplied by 100 to give a percentage. This is:

[tex]percent by mass= \frac{mass of solute}{mass of solution}x100[/tex]

In this case, you know:

Replacing:

[tex]percent by mass= \frac{7.6 grams}{91 grams}x100[/tex]

Solving:

percent by mass= 0.0835

percent by mass= 8.35 %

Finally, the mass percent of a solution of 7.6 grams sucrose in 83.4 grams of water is 8.35 %.

Learn more:

We have that For the Question"What kinds of elements form an ionic bond"

We see from the Definition that this kind of bond is formed b/w metals and non-metals

From the question we are told

What kinds of elements form an ionic bond

Generally

The Other Name for Ionic bond is covalent bond and it is formed when two ions of variant charge converge  and this kind of bond is formed b/w metals and none metals

Therefore

For the Question

What kinds of elements form an ionic bond

We see from the Definition that this kind of bond is formed b/w metals and non-metals

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Answer:The chemical element will always get converted during the cycle as it enters different ecosystems. Nitrogen plays an important role as a nutrient in soils. It is needed for photosynthesis in plants. Nitrogen helps decomposers such as bacteria, worms

Explanation:

Answer Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die.

Explanation:

Answer: M = 3 M

Explanation: Molarity is the ratio between the number of moles per unit Liter of volume.

M = n / L

= 6 mole / 2 L

= 3 M

Answer:

C7H7NO

Explanation:

The following were obtained from the question:

C = 69.40%

H = 5.825%

N = 11.57%

O = 13.21%

The empirical formula can be obtained as illustrated in the attached file

Answer:

Volume will goes to increase.

Explanation:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume  

T₂ = Final temperature

So when the temperature goes to increase the volume of gas also increase. Higher temperature increase the kinetic energy and molecules move randomly every where in given space so volume increase.

Now we will put the suppose values in formula.

V₁/T₁ = V₂/T₂

V₂ = V₁T₂/T₁  

V₂ = 4.5 L × 348 K / 298 k

V₂ = 1566 L.K / 298 K

V₂ = 5.3 L

Hence prove that volume increase by increasing the temperature.

The net force on the cube in Diagram A is 3 N to the right. The net force on the cube in Diagram B is 47 N downwards.

Diagram A

This diagram shows a cube with two forces acting on it: a 5 N force to the left and an 8 N force to the right. To calculate the net force, we need to subtract the smaller force from the larger force.

Net force = 8 N - 5 N = 3 N to the right

Diagram B

This diagram shows a cube with two forces acting on it: a 128 N force upwards and a 175 N force downwards. To calculate the net force, we need to subtract the smaller force from the larger force.

Net force = 175 N - 128 N = 47 N downwards

The net force on an object is the sum of all the forces acting on it. If the net force is zero, then the object is in equilibrium. If the net force is not zero, then the object will accelerate in the direction of the net force.

To calculate the net force on an object, we need to add up all the forces acting on it, taking into account their magnitudes and directions. We can use the following formula:

Net force = F1 + F2 + F3 + ...

Where F1, F2, F3, etc. are the magnitudes of the forces acting on the object.

In the case of Diagram A, we have two forces acting on the cube: a 5 N force to the left and an 8 N force to the right. To calculate the net force, we need to subtract the smaller force from the larger force:

Net force = 8 N - 5 N = 3 N to the right

This means that the cube will accelerate to the right.

In the case of Diagram B, we have two forces acting on the cube: a 128 N force upwards and a 175 N force downwards. To calculate the net force, we need to subtract the smaller force from the larger force:

Net force = 175 N - 128 N = 47 N downwards

This means that the cube will accelerate downwards.

Answer:74 calories to kilocalories  =0.074

Hope this helps

Answer:

Pressure is directly proportional to the density of a substance.

Explanation:

Pressure is a measure of force per unit area. Density is defined as mass per unit volume i.e the ratio of mass of a substance to it's volume.

Thus, it means that an increase in pressure results in an increase in density and vice-versa.

Answer:

None of the options are correct. The answer to the question is 353.2g

Explanation:

The equation for the reaction between is given below:

KI + AgNO3 —> KNO3 + AgI

Molar Mass of KI = 39 + 127 = 166g/mol

Molar Mass of AgI = 108 + 127 = 235g/mol

From the equation,

166g of KI produced 235g of AgI.

Therefore, Xg of KI will produce 500g of AgI i.e

Xg of KI = (166 x 500)/235 = 353.2g

Answer:

false

Explanation:

it can be differ when the concentration,surface area and when the rate of reaction is changed

Final answer:

The statement is false. Reaction rates are affected by the size of the reactant particles because smaller particles have a greater surface area, which increases the number of collisions and the rate of reaction.

Explanation:

The statement that chemical reactions occur at the same rate no matter what the size of the reactant particles is false.

The rate of a chemical reaction is influenced by various factors. One of these factors is the state of subdivision of the reactants, which pertains to the size of the reactant particles. A reaction between two reactants, for example, will often occur at a faster rate if one reactant is in the form of many small particles rather than one large lump. This is because many small particles have a greater surface area, leading to more collisions, which increases the reaction rate.

Other factors affecting the rate include the chemical nature of the reacting substances, temperature, concentration of the reactants, and the presence of a catalyst. Each of these can have a significant impact on how quickly a reaction proceeds.

Answer:

8.46mph

Explanation:

Given parameters:

Distance run = 1500m

Time taken to cover distance = 403s

Unknown:

Average speed in mph = ?

Solution:

The average speed of a travel is the rate of change of the total distance with time.

Speed is a scalar quantity that specifies magnitude of the travel but no direction.

    Average speed = [tex]\frac{Total distance covered }{Time taken}[/tex]

we need to covered distance to miles from m and time in seconds to hours.

       1609m = 1 mile

       1500m = [tex]\frac{1500}{1609}[/tex] =  0.93miles

                       3600s = 1hr

                        403s  = [tex]\frac{403}{3600}[/tex]  = 0.11hr

Average speed = [tex]\frac{0.93}{0.11}[/tex]   = 8.46miles per hour

Answer:

rain acts like a light prism which displays rainbow colors when light is shown through

Answer:

We see rainbow when the sun is behind us and and falling rain is in front of us

Explanation:

when sunlight strikes a falling drop of water it is retracted , changed indirection, by the surface of the water

The below is about the energy exchanges in earth systems.                                                                                                          

Explanation:

Energy exchanges in Earth's system revolves around Earth's main energy outputs which are visible and infrared radiation, reflected light and thermal infrared radiation. ultraviolet radiation and visible radiation,  gamma rays, X-rays and ultraviolet radiation.

Explanation:

Answer:

False

Explanation:

The temperature at which a solid melts, known as its melting point is highly characteristic of a compound and element.

The melting point of pure substances, compounds and elements is definite and not varied.

Therefore, melting point of most solids is characteristic of compounds and elements.

Answer:

28.45L

Explanation:

1mole of a gas occupy 22.4L at stp. This implies that 1mole of He also occupy 22.4L at stp.

Now if 1mole of He occupied 22.4L at stp, then, 1.27mol will occupy = 1.27x22.4 = 28.45L

Answer:

28.45L

Explanation: