Which is the best example and explanation that a physical change has occurred?
fireworks exploding, because energy is released as light and heat
gasoline burning, because it forms water vapor and carbon dioxide
O crushing an ice cube, because the chemical structure of the ice cube is changed
dicing potatoes, because the molecules are separated but remain the same substance

Answer:

Explanation:

When volume of gas is V , pressure is P and temperature is T , if n be number of moles of gas

PV / RT = n , R is universal gas constant .

When volume becomes .5 V , pressure P and temperature T

number of moles = Px .5 V / RT = .5 PV / RT = .5 n

Number of moles of gas becomes half .

so 4 moles becomes  2 moles

No of moles lost = 4 - 2 = 2 moles.

Answer:  The volume occupied at an altitude of 20.0 km is 34.5289 L

Explanation:

Boyle's Law: This law states that pressure is inversely proportional to the volume of the gas at constant temperature and number of moles.

[tex]P\propto \frac{1}{V}[/tex]     (At constant temperature and number of moles)

where,

[tex]P_1[/tex] = initial pressure of gas = 101.325 kPa ( sea level)

[tex]P_2[/tex] = final pressure of gas = 10 kPa

[tex]V_1[/tex] = initial volume of gas = 3.40774 L

[tex]V_2[/tex] = final volume of gas = ?

Now put all the given values in the above equation, we get the final pressure of gas.

[tex]101.325\times 3.40774=10\times V_2[/tex]

[tex]V_2=34.5289L[/tex]

Therefore, the volume occupied at an altitude of 20.0 km is 34.5289 L

Answer:

There are:

Explanation:

First calculate the percentage of Cu and S in the compound:

These percentages will remain the same no matter how much of the compound we analyze.

Now we calculate the grams of Cu and S in 3801 kg of the compound:

Answer:

Evaporation is a technique used to separate out homogeneous mixtures where there is one or more dissolved salts.

Explanation:

Hope this helps :)

Answer:

m = 0.00659 kg = 6.59 g

Explanation:

From Faraday's Law of Electrolysis, we know that:

m = ZQ

where,

m = mass of silver deposited = ?

Q = charge supplied = (1.65 A-hr)(3600 s/1 hr) = 5940 C

Z = electrochemical equivalent of silver = 1.18 x 10⁻⁶ kg/C

Therefore,

m = (1.11 x 10⁻⁶ kg/C)(5940 C)

m = 0.00659 kg = 6.59 g

The mass of silver that would be deposited by a battery is 6.65 grams

The precipitation of Ag requires the removal of one electron. The reduction process for silver electrode at the cathode is as follows:

[tex]\mathbf{Ag^+ + e^- \to Ag(s)}[/tex]

∴

In one mole of an electron, the charge carried = 96500 C

Recall that:

The atomic mass of silver (Ag) = 108 g

∴

The mass of silver that would be deposited in a 5940 C can be computed as:

[tex]\mathbf{=5940\ C \times \dfrac{108 \ g }{96500 \ C}}[/tex]

= 6.65 grams

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Since the forces equal to 0, it's balanced because the object isn't moving.

Answer:

–156 °C

Explanation:

The following data were obtained from the question:

Initial temperature (T1) = –20 °C

Initial volume (V1) = 140 mL

Final volume (V2) = 65 mL

Final temperature (T2) =?

Pressure = constant.

Next, we shall convert –20 °C to Kelvin temperature. This can be obtained as follow:

T(K) = T(°C) + 273

Initial temperature (T1) = –20 °C

Initial temperature (T1) = –20 °C + 273 = 253 K.

Next, we shall determine the new temperature of the gas as follow:

Initial temperature (T1) = 253 K

Initial volume (V1) = 140 mL

Final volume (V2) = 65 mL

Final temperature (T2) =?

V1/T1 = V2/T2

140/253 = 65/T2

Cross multiply

140 × T2 = 253 × 65

140 × T2 = 16445

Divide both side by 140

T2 = 16445 /140

T2 = 117 K

Finally, we shall convert 117 K to celcius temperature. This can be obtained as follow:

T(°C) = T(K) – 273

T2 = 117 K

T2 = 117 K – 273

T2 = –156 °C

Thus, the new temperature of the gas is –156 °C

Answer:

See image attached

Explanation:

The reaction of toluene with alkaline potassium permanganate in the presence of heat leads to the oxidation of the -CH3 to give benzoic acid.

Reaction benzoic acid with HNO3/H2SO4 yields the nitronium ion (NO2+).

Recall that -COOH is a metal director and deactivated the ring towards electrophilic substitution hence the m-nitrobenzoic acid is formed.

Reaction with FeBr3/Br2 yields the product shown in the image attached.

Explanation:

The energy released due to breakage of bond or we can say that protons and electrons go from a structure of higher potential energy to lower potential energy. During this change, potential energy is converted to kinetic energy in form of heat.

Generally chemical potential energy is accessed in form heat, which the difference between the potential energies of reactant and product.

Answer:

The temperature is on the y-axis and the time is on the x-axis.

Explanation:

Which statement describes how phase changes can be diagrammed as a substance is heated? (D is the answer)

The phase is on the y-axis and the temperature is on the x-axis.

The temperature is on the y-axis and the phase is on the x-axis.

The time is on the y-axis and the temperature is on the x-axis.

The temperature is on the y-axis and the time is on the x-axis.

Which statement describes the appearance of a temperature-vs.-time graph? (C is the answer)

A horizontal line shows that the temperature increases at a constant rate over time.

A vertical line shows that the temperature decreases at a constant rate over time.

Horizontal lines where the temperature is constant during phase changes connect upward-sloping lines where the temperature increases.

Horizontal lines where the temperature increases are connected by upward-sloping lines where the temperature is constant for each phase.

Answer:

A and D

Explanation:

Answer:

NaClO; the contained elements ae Na, Cl, O.

Answer:

it has 12 carbon atoms and 22 hydrogen atoms and 11 oxygen atoms

Explanation:

Answer:

96.72 m/min

Explanation:

The following data were obtained from the question:

Time (t) = 56.7 s

Distance (d) = 100 yard

Rate (R) =?

Next, we shall convert 56.7 s to minutes. This can be obtained as follow:

60 s = 1 min

Therefore,

56.7 s = 56.7 s × 1 min /60 s

56.7 s = 0.945 min

Next, we shall convert 100 yard to metre (m). This can be obtained as follow:

1 yard = 0.914 m

Therefore,

100 yard = 100 yard × 0.914 m /1 yard

100 yard = 91.4 m

Finally, we shall determine the rate of the swimmer as follow:

Time (t) = 0.945 min

Distance (d) = 91.4 m

Rate (R) =?

R = d/t

R = 91.4/0.945

R = 96.72 m/min

Thus the rate of the swimmer is 96.72 m/min

Answer:

309 K

Explanation:

Step 1: Convert the pressure to atm

We will use the conversion factor 1 atm = 760 mmHg.

732 mmHg × 1 atm/760 mmHg = 0.963 atm

Step 2: Calculate the moles (n) of the ideal gas

We will use the ideal gas equation.

P × V = n × R × T

n = P × V/R × T

n = 0.963 atm × 8.4 L/0.0821 atm.L/mol.K × 298 K

n = 0.33 mol

Step 3: Calculate the temperature change

We will use the following expression.

Q = n × Cp × ΔT

ΔT = Q/n × Cp

ΔT = 75 J/0.33 mol × 20.79 J/mol.K

ΔT = 11 K

Step 4: Calculate the final temperature

T = 298 K + 11 K = 309 K

There is a golden role of solubility, polar solute dissolve in polar solvent and non polar solute dissolve in non polar solvent. Therefore, the correct option is option B that is Salt and water.

Solutions are a homogeneous mixture of two or more substances. A solution is a homogeneous mixture of solvent and solute molecules. Solvent is a substance that is in large amount in solution. solute is the substance which is in small amount in a solution. There are two types of mixture that is homogeneous and heterogeneous. Solution is a homogeneous solution.

Salt and water because salt is transparent and will dissolve into the water among given solute, salt NaCl is a polar solute which will dissolve in polar solvent that is water.

Therefore, the correct option is option B that is Salt and water.

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Answer:

Cell

Explanation:

I just passed this unit a month ago.

Answer:

It is 6. Cell

Explanation:

Cells make up the smallest level of a living organism such as yourself and other living things. The cellular level of an organism is where the metabolic processes occur that keep the organism alive. That is why the cell is called the fundamental unit of life.

I really hope this helped. God bless you and have a great day! :-)

Answer:

The Universe is constantly expanding and as it expands the stars and objects in space move farther apart, just like the points on the balloon when air is blown into it. Density and distribution of "stars" as the balloon expands because when volume increases the density will increase.

Hope this Helps

Answer:

I play!!!!!!!!

Explanation:

Answer:

A chemical reaction is the process in which atoms present in the starting substances rearrange to give new chemical combinations present in the substances formed by the reaction. These starting substances of a chemical reaction are called the reactants, and the new substances that result are called the products.

Answer:

The original concentration of the HCl is: 0.01925 M

Explanation:

Equation:

HCl+NaOH-------> NaCl+H₂O

Volume of NaOH added = 0.05 M

No of moles of NaOH = 15.4 mL [tex]x\frac{1 L}{1000 mL} x\frac{0.05 mol NaOH}{L}[/tex]

= 0.00077 mol NaOH

Then,

Volume of HCl solution = 40 mL x 1/1000 mL

= 0.0400 L

Therefore,

Concentration of HCl = 0.00077 mol/0.0400 L

= 0.01925 M

Now, to find the pH:

pH = -log₁₀[H⁺]

     = -log₁₀(2x10⁻⁶)

     = 5.7

Answer: Atoms of carbon and hydrogen

Explanation:

Answer:

They are plants also known as plankton and they produce about 80-85% of the world's oxygen.

Explanation:

The cellular respiration process, which generates ATP as the final result, employs oxygen and sugar as reactants. So, the correct option is A.

Cellular respiration is the process by which organisms combine oxygen with food molecules, channeling the chemical energy from those resources into life-sustaining activities while eliminating carbon dioxide and water as waste.

Both oxygen and glucose are reactants in the mobile respiratory system. ATP is the primary component of mobile respiration; waste products include carbon dioxide and water.

Oxygen might be present or absent while cells are respiring. Nonetheless, the activity is essentially known as "cellular respiration" because the cell seems to "respire" by consuming molecular oxygen (as an acceptor of electron) and exhaling carbon dioxide (as an end product).

Therefore, the correct option is A.

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Your question is incomplete, most probably the complete question is:

The process shown in the diagram produces oxygen and sugar. Which

process uses oxygen and sugar as reactants?

Chloroplast

Mitochondrion

Sugar

CO, +H,0

ATP

Heat

Respiration

A. Cellular respiration

B. Water cycle

c. Transpiration

D. Photosynthesis

Answer:

a. PbSO4, Ksp = 1.7x10^-8.

Explanation:

Hello!

In this case, since the solubility product indicates how likely a solid is able to ionize and consequently dissolve in water, we can infer that the larger the solubility product Ksp, the more ions are able dissolve in water; therefore the proper answer goes with the largest Ksp, which is a. PbSO4, Ksp = 1.7x10^-8 since the power goes closer to 1 than the other options.

Best regards!

Answer:

Noble gases... (You already know...)

Explanation:

The right-most column of the periodic table contains atoms with full electron shells, also known as Noble Gases.

Hope this helped!

Answer:

Noble gases

Explanation:

The six elements listed in the last column of the table (Group 18) of the periodic table are collectively referred to as the noble gases. All of the noble gases have the maximum number of electrons possible in their outer shells (two electrons in helium’s outer shell, and eight electrons for all the others), making them stable.