Why do your feet burn when you walk across beach sand on a sunny summer
day?
A. Heat is transferred by thermal conduction.
B. Heat is transferred by convection heating.
C. Heat is transferred by frictional heating.
D. Heat is transferred by radiation warming.

B.

Both use kinetic energy to produce electricity is a similarity between power plants that use water as an energy source and those that use wind as an energy source.

Explanation:

Kinetic energy Is the intrinsic energy that an object or substance possesses due to its motion. All power plants that use water as an energy source utilize the kinetic energy of water to produce electricity. For example, hydro-power plants use the kinetic energy of water flowing due to gravity. Tidal power plants utilize the kinetic energy of water flowing due to tidal changes and geothermal powerplants utilize the energy of steam-water ejecting underground through fissures.

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Answer: b. the total number of gas molecules will decrease.

Explanation:

According to principle, how will a pressure increase affect a system that includes matter in the gas phase and another phase that means the total number of gas molecules will decrease.

This principle shows that when we alter a system in equilibrium, it will seek to acquire a new state that cancels out this disturbance. Thus, there is a shift in equilibrium, that is, a search for a new equilibrium situation, favoring one of the reaction directions.

principle concerns the response of systems in equilibrium when subjected to a perturbation. Simply put, the principle says that a system in equilibrium when disturbed tends to adjust itself in order to remove the disturbance and restore equilibrium.

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Answer:

Because there is a lesser if not absent atmospheric pressure on Mars relative to earth

Explanation:

On earth the liquid water will experience atmospheric downward pressure due to the earth's atmosphere which will require it to evaporate at a vapour pressure that is greater than the atmospheric pressure. This is not the case for Mars which lacks an atmosphere due to its weak gravitional pull, water will therefore evaporate easily on mars than on earth

Answer:

heterogeneous catalyst

Explanation:

The reaction equation:

                        MnO₂[tex]_{s}[/tex]

         H₂O₂[tex]_{l}[/tex]         →             2H₂[tex]_{g}[/tex]     +   2O₂[tex]_{g}[/tex]

A catalyst is any species that speeds up the rate of chemical reactions. It does not get used up in the reaction but helps facilitate the rate by which two species combines.

In this reaction, MnO₂ is the catalyst used in this reaction.

The catalyst still remains at the end of the reaction.

  Now, we know that from the subscript, the reactant is in liquid phase, the products are in gaseous phase and the catalyst is in solid phase.

A catalyst in a reaction in a different phase with the reactants is called a heterogeneous catalyst.

Answer:

The answer is B. A heterogeneous catalyst is being used in the reaction.

Explanation:

A rock with a striped pattern is classified as a metamorphic rock because its characteristics indicate that it has been transformed under high heat and pressure, realigning its mineral structure.

When classifying a rock with stripes, it suggests a transformation under high heat and pressure which typically results in the reorientation of minerals within the rock. This description fits the formation process of metamorphic rocks. Therefore, any rock with a striped pattern is likely a metamorphic rock, as igneous rocks form from the cooling of magma or lava and would not have stripes, and sedimentary rocks are characterized by layers formed from deposited sediment and can sometimes contain fossils.

Final answer:

The rock in question should be classified as metamorphic due to its striped look, which is a result of high heat and pressure reorienting minerals within the rock, characteristic of metamorphism.

Explanation:

You would classify this rock as metamorphic because it has a striped look, which is indicative of the foliation process that occurs when a pre-existing rock is transformed due to high heat and pressure. This reorientation of minerals within the rock often gives it a layered or striped appearance, a characteristic feature of metamorphic rocks. Sedimentary rocks, while they also have layers, are formed from particles of pre-existing rocks or organic material that have been compacted and cemented together.

These can sometimes contain fossils, but it is the presence of distinct stripes from the reorientation of minerals that suggests a metamorphic origin in the case you've mentioned. Igneous rocks with large crystals are formed from magma that solidifies slowly beneath the Earth's surface, but these do not have the striped appearance associated with metamorphic rocks.

Answer:

                     Molarity  =  5.52 mol.L⁻¹

Explanation:

             Molarity is the amount of solute dissolved per unit volume of solution. It is expressed as,

                         Molarity  =  Moles / Volume of Solution    ----- (1)

Data Given;

                  Mass  =  250.0 g

                  Volume  =  775 mL  =  0.775 L

First calculate Moles for given mass as,

                   Moles  =  Mass / M.mass

                   Moles  =  250.0 g / 58.44 g.mol⁻¹

                   Moles  =  4.277 mol

Now, putting value of Moles and Volume in eq. 1,

                        Molarity  =  4.277 mol ÷ 0.775 L

                        Molarity  =  5.52 mol.L⁻¹

Answer:

Molality of solution = 0.973 m

Explanation:

Molality : It is defined as the moles of the solute per Kg mass of solvent.It is not temperature dependent.

Solute = Substance which is present in less quantity in the solution is called the solute. Here , Sucrose is the solute.

Solvent = Substance which is present in more quantity is the solvent. Here water is solvent.

[tex]Molality=\frac{moles\ of\ solute}{mass\ of\ solvent}[/tex]

Density = It is defined as the mass per unit volume.

[tex]Density=\frac{mass}{Volume}[/tex]

Mass of Solute = 137.9 g

[tex]Moles=\frac{mass}{Molar\ mass}[/tex]

Molar mass of sucrose =

[tex]C_{12}H_{22}O_{11}[/tex]= 12(mass of C)+22(mass of H)+11(mass of O)

= 12(12)+22(1)+11(16)

= 144+22+176

= 342 g/mol

[tex]Moles=\frac{mass}{Molar\ mass}[/tex]

[tex]Moles=\frac{137.9}{342}[/tex]

[tex]Moles=0.403[/tex]

Moles = 0.403 moles

Mass of Solvent = 414.1 g  (water)

[tex]Molality=\frac{moles\ of\ solute}{mass\ of\ solvent(g)}(1000)[/tex]

[tex]Molality =\frac{0.403}{414.1}\times 1000[/tex]

Molality = 0.973 m

Answer:

Potential

Explanation:

The higher the elevation is the higher the potential energy levels are also the ball is not moving so it is not using kinetic energy.

Answer: Solution attached.

Each equation is now balanced.

Explanation:

Hardness, lustre, and colour.

These Rocks shown in photographs are made of different types of minerals which have properties as follows:

The color of the rock is grey, brown and yellow after it is ground into a powder its color is streak.

The lustre of the rock tells how shiny the rocks are.

Other properties include hardness, texture, shape, and size.

Answer:

The Scientific Method.

True because the biosphere contains

life such as animals and plants Hint the word “bio”

Final answer:

The area of a rectangular field measuring 6.0 m by 8.0 m is 480,000 cm², which is 4.8 × 10⁵ cm² in scientific notation. So the correct option is B.

Explanation:

To calculate the area of a rectangular field in square centimeters, you would use the formula Area = length × width. First, we must ensure that both dimensions are in the same units, so we convert the dimensions from meters to centimeters. There are 100 centimeters in a meter, so:

Next, we calculate the area using the converted measurements:

Area = 600 cm × 800 cm = 480,000 cm²

Therefore, the area of the field in square centimeters is 480,000 cm², which can be expressed in scientific notation as 4.8 × 105 cm2, making option B the correct answer.

Answer:

yes it doese

Explanation:

Final answer:

The reaction is a decomposition reaction where sodium azide decomposes into sodium and nitrogen gas.

Explanation:

The type of reaction represented is a decomposition reaction. This is a chemical reaction where a single compound breaks down into two or more elements or simpler compounds. Sodium azide (NaN3) decomposes into sodium metal (Na) and nitrogen gas (N2). One mole of sodium azide (NaN3) has a molar mass of approximately 65 g/mol.

Therefore, if 23.4 g of sodium azide is used, the moles of nitrogen gas produced can be calculated using the molar mass and the stoichiometry of the reaction. At standard temperature and pressure (STP), one mole of any gas occupies approximately 22.4 liters. By using the stoichiometry of the balanced equation, one can determine the volume of nitrogen gas produced at STP from a given amount of sodium azide.

Answer:                  34.0147 g/mol

Explanation:

Answer:34.02g/mol

Explanation:H2O2

2x1.01 + 2x16 grams/mols

2.02 + 32 =34 .2g/mol

Answer:

its to hard

Explanation:

Answer:

its to hard

Explanation:

Answer:

1. b

2. a

3. d

4. d

Explanation:

Answer:

D = All of these

Explanation:

Physical properties:

Physical properties involve those properties which includes the state of matter.

For example,

Melting point, boiling point, freezing point, density, smell, color

In given example,

The density of gold is 19.32 g/mL

Melting point is 1064.58°C

Boiling point is 2807°C

All these are physical properties.

Chemical properties:

Chemical properties includes those properties which involves the chemical reaction

For example.

Flammability, reactivity, acidity, heat of combustion, toxicity etc.

The reaction of gold with oxygen:

Chemical equation,

3Au + O₂  →  Au₂O₃

Question:

What is the total combined mass of carbon dioxide and water that is produced?

Answer:

109 kg

Explanation:

When 23 kg of gasoline burns by consuming 86 kg oxygen, they produce carbon dioxide and water. To find the total combined mass of carbon dioxide and water, we will use mass conversation law.

According to mass conversation law, the mass of the product is equal to the mass of reagent.

Mass of reagent = Mass of product

In this reaction,

Gasoline + O2 → CO2 + H2O

23 kg + 86 kg → ?

23 kg + 86 kg =  109 kg

Combined mass of carbon dioxide and water will be 109 kg.

Final answer:

To estimate the CO₂ produced from 40 L of gasoline, we multiply the mass of the gasoline (calculated using the density of 0.75 kg/L) by three, resulting in approximately 90 kg of CO₂, which is comparable to human mass.

Explanation:

Based on the provided combustion reaction 2 C8H18 + 25 O2 → 16 CO₂ + 18 H₂O + energy, we can calculate the mass of CO₂ produced from consuming a 40 L tank of gasoline. First, we determine the mass of gasoline using the given density (0.75 kg/L), which is 40 L × 0.75 kg/L = 30 kg of gasoline. Now, using the factor-of-three ratio of CO₂ mass to input fuel mass, we multiply the gasoline mass by three to estimate the CO₂ mass produced. Hence, 30 kg × 3 = 90 kg of CO₂ are produced after burning 40 L of gasoline. If we compare this to the typical human mass, which is roughly between 50-100 kg, one can see that the mass of CO₂ produced is remarkably similar to or even exceeds the mass of an average human.

To test how mass of a reactant affects speed of a reaction, set up an experiment using a consistent reactant, like hydrochloric acid, and alter the mass of another reactant, like sodium bicarbonate. By keeping all other variables constant, you can measure how the varying mass affects the speed of the reaction indicated by when bubbling ceases.

To test how the mass of a reactant affects the speed of a reaction, an experiment could be set up in the following way: Obtain a substance that reacts with a certain reactant. This could be an acid-base reaction or a redox reaction. Let's say the reaction is between hydrochloric acid (HCl) and sodium bicarbonate (NaHCO3) which produces carbon dioxide gas.

Maintain controlled conditions: all other variables such as temperature, pressure, and volume of HCl should be kept constant. The only changing factor would be the mass of the sodium bicarbonate.

Measure the time it takes for the reaction to complete for various masses of NaHCO3. You do this by observing when the bubbling (indicative of CO2 production) stops. You would likely see that increasing the mass of the reactant (NaHCO3) increases the speed of the reaction.

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The correct option is D.

The best experimental design for testing how the mass of a reactant affects the speed of reaction would be 'The mass of one reactant at a time is varied, and the time it takes the reaction to finish is measured', while maintaining other factors like temperature and concentration of other reactants constant. This method is known as the method of initial rates.

The best example of a controlled experiment to test how the mass of a reactant affects the speed of a chemical reaction would be option D: The mass of one reactant at a time is varied, and the time it takes the reaction to finish is measured. This method is known as the method of initial rates, often employed in chemistry to measure reaction rates using different initial reactant concentrations. It is crucial to vary only one aspect while keeping others constant (temperature, concentration of other reactants etc.) to accurately determine the effect one factor has on the reaction speed.

The temperature of the reactants and concentration of the reactants also significantly impacts the rate of a chemical reaction. Higher the temperature, or the concentration, faster the reactions typically occur. However, these other factors need to be controlled in this experiment to singularly test the effect of mass of one reactant.

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The complete question is given below:

You want to test how the mass of a reactant affects the speed of a reaction.

Which of the following is an example of a controlled experiment to test this?

A. The mass of one reactant and the temperature of the reaction mixture are increased until the reaction is finished.

B. The mass of all the reactants is varied, and the time it takes the reaction to finish is measured.

C. The mass of all of the reactants is kept the same, and the mixtures are allowed to react for different lengths of time.

D. The mass of one reactant at a time is varied, and the time it takes the reaction to finish is measured.

Answer:

                       4.57 × 10⁶  nanometers  

Explanation:

                    In this problem we are asked to convert between two units i.e. a meter into nanometer. In sciences, the different units are used for a same quantity (achieved by multiplying conversion factors) to get rid of very small values and get a readable and  intelligible values.

For Example:

In given statement the value of small distance is 4.5 × 10⁻³ meter the real number form of this number is 0.00457. Hence, this number can be converted to a very large number by multiplying it with 10⁹ or 1000000000. Hence,

                         4.5 × 10⁻³  × 1.0 × 10⁹  =  4.57 × 10⁶

Or,

                 4.5 × 10⁻³  meters  =  4.57 × 10⁶  nanometers    

Although the quantity is the same for same units but the number has changed.          

Answer:

78.4L

Explanation:

1 mole of any gas is found to occupy 22.4L at stp. This also indicates that 1mole of oxygen occupy 22.4L.

Therefore,

3.50 moles of oxygen Will occupy = 3.5x22.4 = 78.4L

At Standard Temperature and Pressure (STP), one mole of an ideal gas occupies around 22.4 liters. Accordingly, 3.50 moles of oxygen would occupy a volume of 78.4 liters.

The question is inquiring about the volume an ideal gas, in this case oxygen, would occupy at Standard Temperature and Pressure (STP) given its quantity in moles. It's well established in chemistry that at STP, which is defined as a temperature of 273.15 K and a pressure of 1 atm, one mole of any ideal gas occupies approximately 22.4 liters. This is often known as the standard molar volume. Therefore, to calculate the volume that 3.50 moles of oxygen would occupy, multiply the number of moles (3.50) by the volume of one mole (22.4 L/mole) which results in a volume of 78.4 liters.

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To find the empirical formula of lactic acid, we calculate the moles of C, H, and O from the products of combustion and determine the simplest whole number ratio. The molecular formula is then found by establishing the integer multiple of the empirical formula that matches the given molar mass of lactic acid.

To determine the empirical formula of lactic acid from the given combustion data, we use the mass of products to find the quantity of each element in the original compound. Starting with carbon, 14.7 g of CO2 is produced from the combustion of lactic acid. Using the molar mass of CO2 (44 g/mol), we calculate that there are 0.334 moles of carbon in the 10.0 g of lactic acid.

For hydrogen, 6.00 g of water means there are 0.333 moles of water, which equates to 0.667 moles of hydrogen, since each water molecule contains two hydrogen atoms. Oxygen is a bit more complicated because it's part of both CO2 and H2O. After accounting for the oxygen in CO2 and H2O, we calculate the remainder to be part of the lactic acid. The molar ratios of C:H:O give us the empirical formula, which can be determined by dividing each mole quantity by the smallest amount to find the simplest whole number ratio.

Given a molar mass of 90 g/mol for lactic acid, we can use the empirical formula mass to determine the number of empirical units in the molecular formula. The molecular formula can be found by multiplying the empirical formula by an integer factor that converts the empirical formula mass to the actual molar mass.

Final answer:

Each SI unit measures a specific fundamental quantity: kilograms (kg) for mass, kelvin (K) for temperature, seconds (s) for time, and amperes (A) for electric current.

Explanation:

The student has asked to match each SI unit to the quantity it measures among mass, temperature, time, and electric current. Here are the matches:

These four units are part of the metric system, which uses powers of 10 to relate quantities over various ranges of nature. All other physical quantities, such as force and charge, are derived from these fundamental units.

Answer:

3.5 mol·L⁻¹  

Explanation:

1. Set up an ICE table.

[tex]\begin{array}{cccccc}\text{2NO} & + & \text{I}_{2} &\, \rightleftharpoons \, & \text{2NOI} & & \\ 2.0 & & 4.0 & & 1.0 & & \\ -2x & & -x & & +2x & & \\ 2.0-2x & & 4.0-x & & 1.0+2x & & \\\end{array}[/tex]

2. Solve for x

The equilibrium concentration of NO is 1.0 mol·L⁻¹, so

       1.0 = 2.0 - 2x

2x + 1.0 = 2.0

        2x =  1.0

          x = 0.5

3. Calculate the equilibrium concentration of I₂

[I₂] = 4.0 - x = 4.0 - 0.5 = 3.5 mol·L⁻¹

The concentration of I₂ at equilibrium is calculated to be 3.5 M by using the initial concentration of NO to determine the stoichiometric change in I₂ concentration based on the reaction 2NO(g) + I₂(g) → 2NOI(g).

To find the concentration of I₂ at equilibrium for the reaction 2NO(g) + I₂(g) → 2NOI(g), we use the initial and equilibrium concentrations of NO to determine the change in concentration of I₂. Given the stoichiometry of the reaction, for every 1 mole decrease in NO, there is a 0.5 mole decrease in I₂. The initial concentration of NO is 2.0 M, and at equilibrium, it is 1.0 M, which means there has been a 1.0 M decrease (2.0 M - 1.0 M). The I₂ concentration at equilibrium can be found by subtracting half of this change from the initial I₂ concentration. Since initially the concentration of I₂ is 4.0 M, the equilibrium concentration is calculated as 4.0 M - (1.0 M / 2) = 3.5 M.

Answer:

mass of platinum = 2526.12 g

Explanation:

Given data:

Mass of water = 125 g

Initial temperature of water= 100.0°C

Initial temperature of Pt = 20.0°C

Final temperature = 235°C

Specific heat of Pt = 0.13 j/g°C

Specific heat of water = 4.184 j/g°C

Mass of platinum = ?

Solution:

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = T2 - T1

Q(w) = Q(Pt)

m.c.  (T2 - T1)   =   m.c.   (T2 - T1)

125 g × 4.184 j/g°C ×  (235°C - 100.0°C)  = m × 0.13 j/g°C ×  (235°C - 20°C)

125 g × 4.184 j/g°C × 135°C  = m × 0.13 j/g°C × 215°C

70605 j = m×27.95 j/g

m = 70605 j /27.95 j/g

m = 2526.12 g

To find the mass of platinum dropped into hot water, you would apply the conservation of energy principle and use the specific heat values for both substances. However, the provided temperatures suggest an error in the question, as platinum would not heat to a temperature higher than the water's temperature.

The question involves finding the mass of platinum, which was dropped into hot water, by using the concept of heat transfer between the metal and water. According to the law of conservation of energy, the heat lost by the water is equal to the heat gained by the platinum. To solve for the mass of the platinum, we use the formula q = mcΔT, where 'q' is the heat transfer, 'm' is the mass, 'c' is the specific heat, and 'ΔT' is the change in temperature.

However, the given information seems to contain a mistake, as platinum will not naturally heat up to 235.0°C when dropped into water that is at 100.0°C. There must be an error in the given temperatures. Assuming we had the correct temperature details and using the given specific heats for water (4.184 J/g°C) and platinum (0.13 J/g°C), we could set up the heat transfer equations and solve for the unknown mass of platinum.

Answer:

[tex]\large\boxed{\text{The volume of the gas at a temperature of 300K is 575 liters}}[/tex]

Explanation:

You already know the relation between the volume (V) of the gas and its temperature (T):

           [tex]V/T=1.75[/tex]

The units of V is liters and of T is Kelvin (K).

Thus, the units of the constant 1.75 is liters/K.

Hence, to find the volume (V) of the gas at a temperature (T) of 300 K, you just must solve for V and substitute the temperature to compute V:

         [tex]V=1.75T[/tex]

          [tex]V=1.75liters/K\times 300K=575liters[/tex]

Explanation::

Electrochemical cell

It is the cell that converts the chemical energy in to electric energy .The reaction staking place in it are spontaneous that is occur by itself .

In it the oxidation and reduction both occur .

The one with high electrode potential looses electrons that is it shows : oxidation

Th one with lower electrode potential gains electrons that is  it shows :Reduction .

In this galvanic cell (Zn-Cu couple )

The oxidation occurs at anode that is :

Zn-2e---->Zn²⁺

The reduction occurs at cathode :

Cu²⁺  + 2e--->Cu

Answer:

The correct answer is option B ;)

Explanation: