i need help with this

King Tut's reign came to an end at 3350 years ago

Carbon-14 is a radioactive isotope that can decay. This isotope can be used to determine how long ago an organism died by knowing the ratio from 12C to 14C

Can be formulated

[tex]\tt Nt=No\dfrac{1}{2}^{t/t1/2}[/tex]

Or we can use :

[tex]t=-\frac{1}{\lambda }\text{ln}\left(\frac{{N}_{t}}{{N}_{0}}\right)\longrightarrow t=-\frac{1}{\lambda }\text{ln}\left(\frac{{\text{Rate}}_{t}}{{\text{Rate}}_{0}}\right)[/tex]

The half-life of C-14, 5730 years, so the decay constant :

[tex]\tt \lambda =\dfrac{\text{ln 2}}{{t}_{1\text{/}2}}=\dfrac{0.693}{\text{5730 y}}=1.21\times {10}^{-4}}[/tex]

Assume the initial C-14 activity was 13.6  disintegrations/min/g of C

[tex]\tt t=-\dfrac{1}{\lambda }\text{ln}\left(\dfrac{{\text{Rate}}_{t}}{{\text{Rate}}_{0}}\right)=-\dfrac{1}{1.21\times {10}^{-4}}\text{ln}\left(\dfrac{9.07}{13.6}\right)=\text{3348}\approx 3350~y[/tex]

Answer:

Explanation:

Salt water intrusion can cause the fresh water in wells to become contaminated with saltwater.

There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Therefore, salt water intrusion can cause the fresh water in wells to become contaminated with salt water.

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

An ionic compound is a metal and nonmetal combined compound. Ionic compound are very hard. They have high melting and boiling point because of strong ion bond.

The compound that is ionic in nature can be dissociated very easily in water. Since ionic compounds are polar in nature, they readily dissolve in water. Salt water intrusion can cause the fresh water in wells to become contaminated with salt water.

Therefore, salt water intrusion can cause the fresh water in wells to become contaminated with salt water.

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Answer:

1.1 × 10⁵ J

Explanation:

Step 1: Given data

Step 2: Calculate the change in the temperature

ΔT = 192.4 °C - 70 °C = 122 °C

Step 3: Calculate the heat required (Q)

We will use the following expression.

Q = c × m × ΔT

Q = 0.89 J/g.°C × 1000.0 g × 122 °C

Q = 1.1 × 10⁵ J

Explanation:

sodium atom is neutral while sodium ion is a charged specie with a charge of +1

Answer: Final temperature for given mass of water is [tex]24.6^o C[/tex].

Explanation:

Given: mass = 630.1 g, specific heat = 418 [tex]J/g^{o} C[/tex], q = 950 J, T = [tex]24.2^o C[/tex]

Formula used:  [tex]q = mC \Delta T[/tex]

where, q = heat energy

            m = mass

            C = specific heat

            [tex]\Delta T[/tex] = change in temperature = [tex](T_2 - T_1)[/tex]

  950 J = [tex]630.1 g \times 4.18 J/g^o C \times (T_2 - 24.2^o)[/tex]

          [tex]T_2 = 24.6^o C[/tex]

Answer:

T2 = 24.56°C

Explanation:

Given data:

Mass of water = 630.1 g

Specific heat of water = 4.18 J/g.°C

Initial temperature = 24.2°C

Heat absorbed = 950 J

Final temperature = ?

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

by putting values

950 J = 630.1 g × 4.18 J/g.°C ×  (T2 - 24.2°C)

950 J = 2633.82 j/°C ×  (T2 - 24.2°C)

950 J / 2633.82 j/°C =  (T2 - 24.2°C)

0.36°C  + 24.2°C = T2

T2 = 24.56°C

Answer:

Chemical Formula: Fe2O3.

Explanation:

Iron(III) oxide, ferric iron, hematite, red iron oxide, synthetic maghemite, colcothar, or simply rust—is one of the several oxide compounds of iron, and has paramagnetic properties

The formula for Carbon Trioxide is CO₃.

In Carbon Trioxide (CO₃), one carbon atom is bonded to three oxygen atoms. The subscript "3" indicates that there are three oxygen atoms in the molecule.

Carbon trioxide (CO₃) is not a stable molecule, and it does not exist as a discrete compound. The actual chemical formula for this compound does not represent a real chemical species.

Carbon trioxide was once proposed as a hypothetical compound with a triangular cyclic structure containing one carbon atom and three oxygen atoms. However, further research and experiments have shown that this structure is not viable due to the instability and high reactivity of such a compound.

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Answer:

[tex]3Li_2SO_4+2K_3PO_4\rightarrow 2Li_3PO_4+3K_2SO_4[/tex]

Explanation:

Hello!

In this case, when lithium sulfate and potassium phosphate solutions are mixed to yield lithium phosphate and potassium sulfate, the following chemical equation comes up:

[tex]Li_2SO_4+K_3PO_4\rightarrow Li_3PO_4+K_2SO_4[/tex]

However, as atoms are not balanced we apply the inspection method to obtain:

[tex]3Li_2SO_4+2K_3PO_4\rightarrow 2Li_3PO_4+3K_2SO_4[/tex]

Best regards!

Answer:

A) 6.023*10^23

B)6.023*10^22

Explanation:

AVAGADRO it would take nearly 1 mole of chalk so

1 mole of any substance contain 6.023*10^23 particles.

AVAGADRO it would take nearly 1 mole of ink to print so

1 mole of any substance contain 6.023*10^23 particles.

Carbon-14 dating radioactive element is used to determine the absolute age of Holocene animal remains .

A radioactive element is one with an unstable nucleus, which radiates alpha, beta or gamma radiation and gets converted to a stable element.

Radioactive elements are unstable isotopes that release subatomic particles or energy as they decay.

Carbon-14 dating -

Carbon 14 dating, also defined as radiocarbon dating, is a method of determining age .

It is  used to determine the age of everything from bones and plant fibers, to wood and pollen.

Hence the radioactive element Carbon-14 dating is used to determine the absolute age of Holocene animal remains .

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Answer:

c. 300 cal

Explanation:

To calculate the heat, we use the following equation:

heat = m x Cp x ΔT

Where m is the mass of water, Cp is the specific heat of water (which is 1 cal/g.°C) and ΔT is the change in temperature (calculated as the difference between the final T and the initial T).

We have the volume of water (10 ml) but not the mass. As the density of water is 1 g/ml, the mass of water is:

density = mass/volume ⇒ mass = density x volume = 1 g/ml x 10 ml = 10 g

The change in temperature (ΔT) is:

ΔT= Final T - Initial T = 25°C - (-5°C) = 30°C

Finally, we introduce the data to calculate the heat:

heat = 10 g x 1 cal/g.°C x 30°C = 300 cal

Therefore, the correct option is c. 300 cal

Answer:

m = 2 g

Explanation:

Given data:

Initial temperature = 45°C

Final temperature = 35°C

Heat evolved = 84 j

Mass of water = ?

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

specific heat capacity of water is 4.18 J/g.°C

ΔT = 35°C - 45°C

ΔT = - 10°C

84 j = m ×4.18 J/g.°C ×- 10°C

84 j = m × -41.8 J/g

m = 84 j / -41.8 J/g

m = 2 g

negative sign shows heat is evolved.

Answer:

100 POINTS! (50 split up) PLSSSSSSSSSS HELP!!! I REALLY NEED IT SO MUCH :( I PROMICE TO GIVE BRAINLIEST AND FIVE STARS AND A THANKS! 6TH GRADE SCIENCE! i used all my points for this!

You measure the mass of an apple using a balance. You get these three measurements:

Trial 1: 167.0 g

Trial 2: 166.9 g

Trial 3: 167.2 g

You know that the true mass of the apple is 172 g. Describe your results in terms of precision and accuracy. Explain your answer in a paragraph for the best grade.

Explanation:

Answer:

CH2

Explanation:

What is the empirical formula of a compound that contains 20.0g carbon and 3.37g hydrogen? Divide by the smallest number of moles. The empirical formula is CH2.

Explanation:

11.11 grams of hysrogen is requited to make 100 g of water

Answer:

light blue

Explanation:

the second one

Answer:

D.

Explanation:

Yan Lang po Alam ko

Answer:

D. 4.75 m/s west

Explanation:

You can immediately get the answer once you know the formula for velocity.

The distance is 95 meters while the time is 20 seconds. All you have to do is to divide 95 meters by 20 seconds.

Let's solve:

Since Brenda is going west with her her skateboard, then you have to add west as her direction.

Brenda's velocity is 4.75 m/s west.

Answer:

The answers to your questions are given below

Explanation:

To successfully answer the questions given above, it is important that we know the various units of measurement of volume, pressure and temperature respectively.

For Volume:

Some measuring units of volume include:

1. Litre (L)

2. Millilitre (mL)

3. Cubic centimetres (cm³) etc

For Pressure:

Some measuring units of pressure include:

1. Atmosphere (atm)

2. Millimetres of Mercury (mmHg)

3. Torr

4. Pascal (Pa)

5. Kilo pascal (KPa) etc

For Temperature:

Some measuring units of temperature include:

1. Kelvin (K)

2. Degree Celsius (°C)

3. Degree Fahrenheit (°F)

Now, we shall answer the questions given above as follow:

A. 56 °C => Temperature

B. 247.3 KPa => Pressure

C. 23.3 mL => Volume

D. 298 K => Temperature

E. 1.24 atm => Pressure

F. 482 torr => Pressure

G. 0.50 L => Volume

H. 120.9 mmHg => Pressure

Answer: carbon dioxide and water

Explanation: hydrocarbons are compounds of carbon and hydrogen. Combustion is another word for oxidation. Oxygen splits, the CH bonds, oxidising both the C and the H. The simplest hydrocarbons, the alkanes, have the general formula C(n)H(n+2)

The combustion reaction is

(3n+1)O2 + 2C(n)H(2n+2) —> 2nCO2 + (2n+2)H2O

The products of a complete combustion reaction of a hydrocarbon in the presence of sufficient oxygen are carbon dioxide ([tex]CO_2[/tex]) and water ([tex]H_2O[/tex]).

Carbon dioxide and water are the end products of a hydrocarbon's full combustion reaction when there is enough oxygen present. The general equation: can be used to express this reaction.

Hydrocarbon + Oxygen -> Carbon Dioxide + Water

For example, if we consider the combustion of methane ([tex]CH_4[/tex]), the equation would be:

[tex]CH_4 + 2O_2 - > CO_2 + 2H_2O[/tex]

Here, one molecule of methane reacts with two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water.

Thus, the specific products of a hydrocarbon combustion reaction depend on the hydrocarbon being burned.

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Answer:

metallic bonding

Explanation:

Copper wire consists of Cu nuclei (that are positively charged due to the positively charged protons) that are surrounded by a "sea" of delocalized electrons (that are negatively charged that move freely throughout the material which is known as metallic bonding.

Answer:

Metallic bonding.

Explanation:

Pure copper is neither covalent nor ironic. It is a bonding called metallic bonding.

Answer:

Following are the solution to the given question:

Explanation:

Let us indicate H3AsO4, an H3A triprotic acid; the ionising equations are as follows:

[tex]\to H_3A \Leftrightarrow H^+ + H_2A^- \\\\[/tex]

[tex]\to Ka_1 = \frac{[H^+][H_2A^-]}{[H_3A]}[/tex]

          [tex]= 10-2.2 = 6.31 \times 10^{-3} \ \ \ \ \ \ \ \ [since\ pKa_1 = 2.2\ and \ Ka = -\log_{10}(pKa)]\\[/tex]

[tex]\to H_2A^{-} \Leftrightarrow H^{+} + HA_2^{-}; \\[/tex]

[tex]\to Ka_2 = \frac{[H^+][HA_2^-]}{[H_2A^-]} = 10-6.8 = 1.58 \times 10^{-7} \\(since pKa2 = 6.8)\\\\\to HA_2^- \Leftrightarrow H^+ + A_3^- ;\\\\ \to Ka_3 = \frac{[H^+][A_3^-]}{[HA_2^-]} = 10-11.6 = 2.51 \times 10^{-12} \\ (given pKa_3 = 11.6)[/tex]

The initial pH; we've 0.00 mL of 0.100 M NaOH – H3A is the main species; Ka1>>Ka2>>Ka3 is also noted. They therefore ignore H2A's disconnection but set up next ICE chart.

[tex]\to H_3A \Leftrightarrow H^+ + H_2A^- \\\\[/tex]

[tex]initial \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0.100 \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0 \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0 \\\\[/tex]

[tex]change \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ - x \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ + x \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ + x\\\\equilibrium \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (0.100 - x) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x\\\\[/tex]

[tex]Ka_1 = \frac{[H^+][H_2A^-]}{[H_3A]} = \frac{(x)(x)}{(0.100 - x)}[/tex]

[tex]\text{x to be much smaller than 0.100 M}\\\\to 6.31 \times 10^{-3} = \frac{x^2}{0.100}\\\\\to x^2 = 6.31 \times 10^{-4}\\\\ \to x = 0.025\ M\\\\\to pH = -\log_{10}[H^+] = -\log_{10}(0.025) = 1.60[/tex]

Answer:

Every chemical equation adheres to the law of every conservation of mass and the states of matter cannot be created or destroyed  

Explanation:

Answer:

Instantaneous Speed

Explanation:

forgive me if its wrong

Answer:

The air would still be too thin to breathe. The lack of atmosphere would chill the Earth's surface. Organisms that need air to breathe would die.

Explanation:

Hope it helped!

Answer:

[tex]2HF(aq)+Ba(OH)_2(aq)\rightarrow BaF_2(s)+H_2O(l)[/tex]

Explanation:

Hello!

In this case, since the neutralization reaction between hydrofluoric acid and barium hydroxide (both aqueous) produce insoluble barium fluoride and liquid water, we can write the chemical reaction as follows:

[tex]HF(aq)+Ba(OH)_2(aq)\rightarrow BaF_2(s)+H_2O(l)[/tex]

However, it needs to be balanced as hydrogen and fluorine are not properly balanced, therefore, we obtain:

[tex]2HF(aq)+Ba(OH)_2(aq)\rightarrow BaF_2(s)+H_2O(l)[/tex]

Best regards!

Answer:

Granules of the hair cortex.

Explanation:

Answer:

It is banding for plato / edmentum

Explanation:

I took notes in the class and in my notes it says -

Human hairs have consistent coloring, whereas animal hair coloring may change radically. This radical change is called banding.

Answer:

X = 27 .

Explanation:

Centigrade scale : melting point O⁰C , boiling point 100⁰C

New scale          melting point -45⁰C   , boiling point 115⁰C

Formula relating the two scale

[tex]\frac{C- 0 }{100-0} =\frac{X-(-45)}{115-( -45) }[/tex]

[tex]\frac{C }{100} =\frac{(X+45)}{(115 +45) }[/tex]

[tex]\frac{C }{100} =\frac{(X+45)}{160}[/tex]

Given C = 45

X = ?

[tex]\frac{45 }{100} =\frac{(X+45)}{160}[/tex]

X + 45 = 72

X = 27 .

Answer:

summer

Explanation:

Because the opposite of winter is summer (warm, hot)

Answer:1.395x10^27 molecules of O2

Explanation:

2Fe + 3/2O2 —> Fe2O3

for every 2 atoms of Fe, 1.5 molecules of O2 —> 1.395x10^27