Please someone help me

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:

See explanation

Explanation:

The Lewis dot structure is a representation of atoms in which the valence electrons on the atoms are shown as dots. Each dot represents a valence electron on the outermost shell of the atom.

Oxygen has six electrons on its outermost shell four of which are two lone pairs. Also, chlorine has seven electrons in its outermost shell. Six of these are lone pairs.

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:

Tetrahedral

And can u give me the brainlist I only need one to get a higher rank and thank u

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:

This question lacks some parts, it should read "Two or more different elements chemically combined make up a"

The answer is a COMPOUND

Explanation:

A compound is a type of pure substance that is formed as a result of the chemical combination of two or more different elements. During this combination, the atoms of the constituent elements are chemically joined together by CHEMICAL BONDS.

An example of a compound is CaCO3, which contains the following elements: Calcium, Carbon and Oxygen. In this compound, the atoms of the above listed elements are joined together by chemical bonds to form a COMPOUND.

Answer:

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

Explanation:

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:

Instantaneous Speed

Explanation:

forgive me if its wrong

Answer:

light blue

Explanation:

the second one

ANSWER

Elements that are similar to neon is helium, and argon

Hope its right if not so advance sorry :)

Answer:

He

Explanation:

plato

Answer:

heat changes energy is by the sun

the sun gives off energy

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:

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:

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:

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:

Explanation:

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

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:

summer

Explanation:

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

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:

20 kg

Explanation:

the mass wont change, so it will still be 20 kg

hope this helps :)

20kgs is the right answer/choice.

Explanation:

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

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 .

Learn more about radioactive element , here:
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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:

D.

Explanation:

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The theoretical yield : 31.11 g

Given

Reaction

3H2+N2=2NH3​

Required

the theoretical yield

Solution

mol = mass : Ar

mol = 5.5 g : 2

mol = 2.75

From the equation, mol ratio of H₂ : NH₃ = 3 : 2, so mol NH₃ =

[tex]\tt \dfrac{2}{3}\times 2.75=1.83[/tex]

mass =mol x MW

mass = 1.83 x 17

mass= 31.11 g

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.