What is the definition of a scientific theory

A) A method of learning that emphasizes reason as the way to understand the world.
B) A brief statement that summarizes past observations and predicts future ones.
C) A model that explains the underlying reasons for observations and laws.
D) The equivalent of a scientific opinion which others may disagree with.
E) None of these.

Answer:

Ancient CO₂ levels can be measured from

1) Air bubbles trapped in deep ancient ice cores (up to 800,000 years ago) or

2) Tree rings (up to 10,000 years ago)

Explanation:

The percentages of CO₂ concentration in the atmosphere from previous or ancient times are found by analyzing the CO₂ content in trapped air located in the deep ancient ice cores present in Antarctica and Greenland such as the EPICA Dome C cores

As the ice is drilled though, the air released from trapped bubbles are captured for analysis and the time frame for the captured bubbles can date back up to 800,000 years

Ancient CO₂ levels can also be measured from tree rings which provide ancient CO₂ levels up to 10,000 years

Answer and Explanation:

For computing the initial quantity of helium we have to apply the law of ideal gas which is shown below:

[tex]pV=nRT\[/tex]

[tex]n=\dfrac{pV}{RT}[/tex]

Now we have to compute the ratio between the initial and the final numbers of moles which is

[tex]\dfrac{n_1}{n_2}=\dfrac{\dfrac{p_1V_1}{RT_1}}{\dfrac{p_2V_2}{RT_2}}[/tex]

The statement defines that

[tex]T_1=T_2,~p_1=p_2.[/tex]

Therefore

[tex]\dfrac{n_1}{n_2}=\dfrac{V_1}{V_2}[/tex]

[tex]\dfrac{n_1}{3.8\times10^{-4}}=\dfrac{230}{860}\iff\\\\ n_1=\dfrac{3.8\times10^{-4}\times230}{860}[/tex]

[tex]\boxed{n_1\approx1.0\times10^{-4}~mol}[/tex]

And, the variables are known is starting volume and ending gas quantity

Answer:

beginning volume and ending quantity of gas

Explanation:

A chemical  reaction involves the interaction of reactants. The substance X ,must be an acid and in this case is CH3COOH

In chemistry, a reaction is said to occur when substances interact in such a way that other new substances are formed.

Now let us look at the particular reaction; NaOH + X ----> NaCH3COO + H2O. The substance X must be an acid. Hence, the most likely susbstance is CH3COOH.

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Answer:

The solution formed is acidic

pH = 0.87

Explanation:

The acid-base reaction of NaOH with HCl is:

NaOH + HCl → NaCl + H₂O

Where 1 mole of NaOH reacts with 1 mole of HCl

In the problem, moles of NaOH and HCl are:

NaOH: 0.0250L × (0.525mol / L) = 0.013125 moles NaOH

HCl: 0.0750 × (0.355mol / L) = 0.026625 moles HCl

As moles of HCl > moles NaOH, HCl is in excess and the solution formed is acidic

Moles in excess of HCl are:

0.026625 moles - 0.013125 moles = 0.0135 moles HCl

As the volume of the solutions is 25.0mL + 75.0mL = 100.0mL = 0.100L, molarity of HCl after reaction is:

0.0135 moles HCl / 0.100L = 0.135M HCl = 0.135M H⁺

As pH is defined as - log [H⁺], pH of the solution is:

pH = -log 0.135M H⁺ = 0.87

pH = 0.87

The pH of the resulting solution of the acid and base mixture is; Acidic with a PH = 0.87

We are given;

Volume of NaOH = 25 mL = 0.025 L

Volume of HCl = 75 mL = 0.075 L

Concentration of NaOH = 0.525 M

Concentration of HCl = 0.355 M

Total volume of solution = 0.025 + 0.075 = 0.1 L

Now, the the equation of the reaction is;

HCl + NaOH = NaCl + H2O

We can see that 1 mole of HCl reacts with 1 mole of NaOH.

Since; number of moles = Volume × concentration

Number of moles of HCl = 0.075 × 0.355

Number of moles of HCl = 0.026625 moles

Similarly;

Number of moles of NaOH = 0.025 × 0.525

Number of moles of NaOH = 0.013125 moles

We can see that the number of moles of HCl is greater than that of NaOH and as such there is excess HCl acid in the mix.

Thus,

Excess moles of HCl acid = 0.026625 - 0.013125

Excess moles of HCl acid = 0.0135 moles

Concentration of this excess HCl is gotten by the formula;

M = Excess moles/total volume

M = 0.0135/0.1

M = 0.135 M

PH of this excess concentration is;

PH = -log [H+]

PH = -log [0.135]

PH = 0.87

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Answer:

23.6°C

Explanation:

Step 1:

Data obtained from the question. This include the following:

Mass = 0.125kg = 0.125 x 1000 = 125g

Initial temperature (T1) = 22°C

Heat (Q) generated in 4.5mins = 835J

Specific heat capacity (C) of water = 4.184J/g°C

Change in temperature (ΔT) =?

Final temperature (T2) =?

Step 2:

Determination of the change in temperature, ΔT of water.

This can be obtained as shown below:

Q = MCΔT

835 = 125 x 4.184 x ΔT

Divide both side by 125 x 4.184

ΔT = 835 / (125 x 4.184)

ΔT = 1.6°C

Therefore, the change in temperature, ΔT is 1.6°C

Step 3:

Determination of the final temperature of water.

This can be obtained as follow:

Initial temperature (T1) = 22°C

Change in temperature (ΔT) = 1.6°C

Final temperature (T2) =?

Change in temperature (ΔT) = Initial temperature – Final temperature

ΔT = T2 – T1

1.6 = T2 – 22

Collect like terms

T2 = 1.6 + 22

T2 = 23.6°C

Therefore, the final temperature of the water is 23.6°C.

Answer:

The angular alignment is 90 degrees

Explanation:

The neap tide is a type of tide which occurs around seven days after a spring tide. This type of tide happens twice every month.

The tide is usually moderate and it exists when the sun and moon are usually at right angles to each other when it occurs. A right angle is also known as 90 degrees which validates the tide occurring at an angle 90.

Answer:

5SiO[tex]_{2}[/tex] + 2CaC[tex]_{2}[/tex] → 5Si + 2CaO + 4CO[tex]_{2}[/tex]

5   2   5   2   4  are your answers.

The right response is to raise the internal gas pressure. When a sealed glass jar is heated, the temperature of the gas within rises, causing the gas molecules to travel faster and collide with the jar's walls more often and with more force, increasing the gas's pressure.

Gas molecules are made up of atoms that are linked together. These interatomic connections function similarly to springs, connecting atoms of varying masses. This connection vibrates at a constant frequency known as the natural frequency. Atoms, molecules, and/or ions are all present in gases, liquids, and solids, but their behavior varies between the three phases. The graphic below depicts the tiny differences. A gas as seen via a microscope. A gas is a condition of stuff that does not have a set volume or form. Air, water vapor, and helium are examples of gases. A gas is a kind of stuff that does not have a defined volume or shape. To put it another way, a gas takes on the shape and volume of its container.

Here,

The correct answer is Increase the internal gas pressure as When a sealed glass jar is heated, the temperature of the gas within rises, forcing the gas molecules to travel faster and hit with the jar's walls more often and with more force, raising the gas's pressure.

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Answer:

C. A linear, nonpolar molecule

Explanation:

Molecules which are alike usually have the same degree of pull which results in them sharing electrons. This sharing of electrons is known as the molecules exhibiting Covalent bonding between them.

The equal pull also results in the cancelling out of electrons and favoring non polar bonds due to the absence of free electrons which would have been able to interact with H2O in a polar binding system.

Answer:

C

Explanation:

APEX

Answer:

C. The product must solve the problem for which it was designed.

Explanation:

Technological design is the study, development and application of technological process with the intent of designing a product to solve required problem.The process could be based on the use of a computer.

Generally, technological process and development always tend to design a problem solver product. Through this process, more new technologies are produced.

Therefore in technological process, the product must solve the problem for which it was designed.

Answer:

C) The product must solve the problem for which it was designed.

Answer:

4

Explanation:

Answer:

[OH] = 6.31 * 10^-7 M

Explanation:

Mathematically;

pH + pOH = 14

Mathematically;

pH = -log [H3O+]

also;

pOH = -log [OH]

From the question; [H3O+] = 1.75 * 10^-8 M

pH = -log [1.75 * 10^-8]

pH = 7.76

since pH is normally given to 1 decimal place

we can say pH = 7.8

Now;

pH + pOH = 14

pOH = 14-7.8

pOH = 6.2

now pOH = -log [OH]

[OH] = -antilog 6.2

[OH] = 6.31 * 10^-7 M

Answer:

it burns through oxygen gas.... through the process known as combustion.... combustion is the process of burning materials in the presence of Air

Answer:

The final temperature will be "12.37°".

Explanation:

The given values are:

mass,

m = 0.125 kg

Initial temperature,

c = 22.0°C

Time,

Δt = 4.5 min

As we know,

⇒  [tex]q=mc \Delta t[/tex]

On putting the estimated values, we get

⇒     [tex]=0.125\times 22.0\times 4.5[/tex]

⇒     [tex]=12.37^{\circ}[/tex]

Answer:

Octane number, measure of the ability of a fuel to resist knocking when ignited in a mixture with air in the cylinder of an internal-combustion engine.

Octane number is also known as octane rating. Octane numbers are based on a scale on which isooctane is 100 (minimal knock) and heptane is 0 (bad knock). The higher the octane number, the more compression required for fuel ignition. Fuels with high octane numbers are used in high performance gasoline engines.

(Hope this helps) Sky

Given question is incomplete. The complete question is as follows.

Balance the following equation:

[tex]H_3PO_4 + Ca(OH)_2 \rightarrow Ca(H_2PO_4)_2 + H_2O[/tex]

Answer: The balanced chemical equation is as follows.

[tex]2H_3PO_4 + Ca(OH)_2 \rightarrow Ca(H_2PO_4)_2 + 2H_2O[/tex]

Explanation:

When a chemical equation contains same number of atoms on both reactant and product side then this equation is known as balanced equation.

For example, [tex]H_3PO_4 + Ca(OH)_2 \rightarrow Ca(H_2PO_4)_2 + H_2O[/tex]

Number of atoms on reactant side:

H = 5

P = 1

O = 6

Ca = 1

Number of atoms on product side:

H = 6

P = 2

O = 9

Ca = 1

In order to balance this equation, we will multiply [tex]H_3PO_4[/tex] by 2 on reactant side and we will multiply [tex]H_2O[/tex] by 2 on product side. Hence, the balanced chemical equation is as follows.

[tex]2H_3PO_4 + Ca(OH)_2 \rightarrow Ca(H_2PO_4)_2 + 2H_2O[/tex]

Answer:2

Explanation:

Answer:

2

Explanation:

Answer:

I think its D sorry if im wrong

Answer:i think its D

Explanation:

Answer:

X= -Y + 2/2     Y=-X + 3/2

Explanation:

I don't know how to simplify it anymore. You would get x=-y+3/2 and y=-x+3/2

Answer:

Explanation:

(-1/2,1)

Answer:

B

Explanation:

The molecular formula for pentyne is C5H8

Answer:

Did you mean solution??

In chemistry, a solution is considered as a special type of homogeneous mixture composed of two or more substances. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent.

Eg: sweet tea or coffee (sugar added to solution)

     bleach (sodium hypochlorite dissolved in water)

HOPE IT HELPS :)

Answer:

burning is a rapid process, rustig is a slow process. burning releases light during the process,rusting does not. burning can speed up with addition of more external conditions, rusting cannot be sped up greately by addition of external materials. burning results in release of large amts of heat, rusting very little amt of heat

Hope helped

plesse give a thank

and most brainlest

-Rust happens when something is unpolished and is old. Burning has been modified by heat.

-Burning is a chemical change. Rust is a physical change.

-Burning something cannot be fixed back to its natural form, while when something is rusted it can possibly be re-used and fixed.

-The texture of something burnt is usually fragile and brittle while rust makes (metal for example) gritty.

-Rust usually forms solely on metals while almost anything can be burned.

note: you asked for 4 answers but i gave you 5 in case you didnt like any of them. Hope this helps!

Answer:

D) The attractive force decreases as the atom gets larger.

Explanation:

i did the lesson and tried all 3, all 3 times, this was the last one and only choice left so it has to be.

Answer:

The attractive force decreases as the atom gets larger.

Explanation:

Answer:

Both of them are polluting the environment. Industrial pollution is the pollution caused from industries and it can be in different forms such as water waster or air pollution. Agricultural pollution is caused from plants or crops that are grown by the farmers. For example, pesticides that may ruin the soil and is dangerous for our environment.

Explanation:

Answer:

Explanation: d

Answer:idioma equivocado ????

Explanation:

Answer:

9*(10+9)

(90+81)

(171) is the answer

Answer:

. A homogeneous mixture of a solid in a gas