Which property of a substance can be determined using a pH indicator?
A. acldity
B. bolling polint
C. density
D. electrical conductivity
E. thermal conductivity​

Answer:

NaCl(aq)

Explanation:

Nacl(aq) is an electrolyte when it melts and it conducts electricity. This is due to the fact that when it is in solution, it dissociates to be Na+ and Cl-. These ions are conductors of electricity. It conducts electricity because of the movements and also the discharge of ions. CH3OH(aq) is not a conductor of electricity therefore the first option is the answer.

Dull black surface are good absorbers of radiation.

The process by which energy in the form of electromagnetic radiation is emitted by a heated surface and travels directly to its absorption point at the speed of light.

The rate at which a body absorbs or radiates thermal radiation relies upon the nature of the surface as well.

According to the Kirchhoff's radiation law, the objects, which are good emitters are also good absorbers.

A blackened surface is an excellent absorber as well as an excellent emitter.

A black body refers to a body, which is regarded as a perfect radiator and absorber of electromagnetic radiations, a dull black surface is a good absorber of heat radiation.

Thus, dull black surface is the best surface for absorbing heat radiation.

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Answer:

Kc = 4.86×10⁻⁶

Explanation:

We begin from the equation:

N₂  +  2H₂ ⇄  2NH₃

We start from 3.47×10⁻² moles of N₂(g) and 6.38×10⁻² moles of H₂(g), so when we reach the equilibrium, we get 6.25×10⁻² moles of H₂.

This data means, that in the reaction we made react:

6.38×10⁻² - x = 6.25×10⁻²

x = 1.3×10⁻³ moles of H₂

As stoichiometry is 1:3, we will know that the moles of N₂ that have been reacted were:

1.3×10⁻³ moles / 3 = 4.33×10⁻⁴ moles of N₂

So, in the equilibrium we would have:

3.47×10⁻² moles of N₂ - 4.33×10⁻⁴ moles of N₂ = 0.0343 moles of N₂

How many ammonia, would we have in the equilibrium?

4.33×10⁻⁴ mol . 2 = 8.66×10⁻⁴ moles (from stoichiometry with N₂, 1:2)

(1.3×10⁻³ mol . 2) / 3 = 8.66×10⁻⁴ moles (from stoichiometry with H₂, 2:3)

Let's make the expression for Kc

Kc = [NH₃]³ / [N₂] . [H₂]²

(8.66×10⁻⁴ )³ / (0.0343 . (6.25×10⁻²)² = 4.86×10⁻⁶

Answer:

XH₂ = 0.4885

XN₂ = 0.4290

XAr = 0.0825

Explanation:

Step 1: Given data

Step 2: Calculate the total pressure (P)

The total pressure is equal to the sum of the partial pressures of all the gases.

P = pH₂ + pN₂ + pAr = 441.0 Torr + 387.3 Torr + 74.5 Torr = 902.8 Torr

Step 3: Calculate the mole fraction (X) of each gas

We will use the following expression.

Xi = pi / P

where,

Xi: mole fraction of the gas i

pi: partial pressure of the gas i

P: total pressure

XH₂ = pH₂ / P = 441.0 Torr / 902.8 Torr = 0.4885

XN₂ = pN₂ / P = 387.3 Torr / 902.8 Torr = 0.4290

XAr = pAr / P = 74.5 Torr / 902.8 Torr = 0.0825

Answer:

Mass = 23.232 g

Explanation:

Given data:

Mass of C₈H₁₈ = 7.58 g

Mass of CO₂ produced = ?

Solution:

Chemical equation:

2C₈H₁₈ + 25O₂      →     16CO₂ + 18H₂O

Number of moles of octane:

Number of  moles =  mass/molar mass

Number of moles = 7.58 g/ 114.23 g/mol

Number of moles = 0.066 mol

Now we will compare the moles of CO₂ with octane from balance chemical equation.

                  C₈H₁₈            :           CO₂

                       2              :              16

                 0.066             :           16/2×0.066 = 0.528

Mass of CO₂ produced:

Mass = number of moles × molar mass

Mass = 0.528 mol × 44 g/mol

Mass = 23.232 g

Answer: The mass of blue copper sulfate is 3.5 g

Explanation:

Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.

This also means that total mass on the reactant side must be equal to the total mass on the product side.

The chemical equation for the heating of copper sulfate crystals is:

Let the mass of blue copper sulfate be 'x' grams

We are given:

Mass of copper sulfate powder = 2.1 grams

Mass of water = 1.4 grams

Total mass on reactant side = x

Total mass on product side = (2.1 + 1.4) g

So, by applying law of conservation of mass, we get:

Hence, the mass of blue copper sulfate is 3.5 grams

Answer:

[tex]a=\frac{f}{d-e}-\frac{b}{c}[/tex]

Explanation:

Hello.

In this case, for the equation:

[tex](a+b/c)(d-e)=f[/tex]

For isolating a, we must first pass (d-e) to divide at the other side as it is initially multiplying:

[tex]a+b/c=\frac{f}{(d-e)}[/tex]

Next, as b/c is adding, it passes to subtract at the other side in order to finally isolate a:

[tex]a=\frac{f}{d-e}-\frac{b}{c}[/tex]

Best regards!

Answer:

Hypothesis: IF a penny is dropped from a building, THEN it would kill a pedestrian below

Controls: Same building, Same distance

Independent variable: Penny

Dependent variable: Pedestrian's death

Conclusion: The hypothesis is rejected

Explanation:

- The hypothesis is a testable explanation to an observed problem or asked question. Based on the cientific question in this question, a possible hypothesis will be: IF a penny is dropped from a building, THEN it would kill a pedestrian below

- Independent variable is the variable that is changed or manipulated in an experiment. In this case, the PENNY is the independent variable

- Dependent variable is the variable that responds to the change made to the independent variable. It is the measured variable. In this case, the dependent variable is the DEATH OF PEDESTRIANS.

- Controls are those variables that is kept constant or unchanged throughout the experiment. The controls in this experiment are: Same building, Same distance of throw etc.

- The conclusion is whether the hypothesis is accepted or not depending on the result of the experiment conducted. In this case, the hypothesis will be rejected if the penny doesn't kill a pedestrian

Answer:

5Ns

momentum= mass *velocity

=1*5

=5Ns

Answer:

the answer is simple

Explanation:

jnnn B upper up of the eye color

Answer:

1. BBEE

2. BbEe

3. BBee

4. BbEE

5. bbEE

6. bbEe

7. Bbee

8.bbee

Answer:

Potassium chloride, KCl , is an ionic compound formed by the electrostatic force of attraction that holds the potassium cations and the chlorine anions together

Explanation:

Answer:

Explanation:

The new volume can be found by using the formula for Boyle's law which is

[tex]P_1V_1 = P_2V_2[/tex]

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

Since we are finding the new volume

[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]

We have

[tex]V_2 = \frac{300 \times 2}{7} = \frac{600}{7} \\ = 85.714285...[/tex]

We have the final answer as

Hope this helps you

Answer:

Ecological islands is just a terminology used, since it isn't surrounded by water like an actual island, instead, it's something isolated from other things, which is the same thing as an island in a way:

Island (geographical) - Land isolated from bigger "main" land masses by water.

Island (ecological) - Land which contains certain isolated features (habitat, plants, etc.).

Explanation:

An ecological island is an area of land, isolated by natural or artificial means from its surrounding land while geographical islands are a body of land surrounded by water.

An ecological island refers to an area of land which is not necessarily an actual island but isolated by natural or artificial means from the surrounding land. A natural micro-habitat exists on sich lands amidst a larger differing ecosystem.

In artificial ecological islands, all non-native species are eradicated, native species are reintroduced and nurtured, and the natural or artificial border is maintained to prevent the reintroduction of non-native species.

A geographical island is a body of land surrounded by water. Continents are also surrounded by water as they are so big but they are not considered islands. Islands may be categorized as either continental or oceanic.

There are so many islands in the lakes, oceans, and rivers around the world. They vary in climate, size, and the types of organisms that inhabit them.

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Answer:

5

Explanation:

The image attached shows the different monochlorination products obtained when chlorine gas is heated with methylcyclobutane.

We must keep in mind that the reaction occurs by free radical mechanism as shown in the image attached. The proportion in which the products are formed depends on the stability of the free radical intermediate leading to that particular product.

Image credit: askiitians

Answer:

PH = 4.0

Explanation:

We are given;

Ka1 = 8.9 × 10^(-8)

Ka2 = 1.0 × 10^(-19)

From the 2 values of K given above, we can see that Ka2 is far smaller than Ka1.

Thus, Positive hydrogen ion (H+) will be majorly formed from first dissociation which is Ka1.

Now, the breakdown of the H2S solution is;

H2S⇌[H+] + [HS−]

Thus;

Ka1 = [[H+] × [HS2^(-)]]/(H2S)

HS2^(-) also has a positive hydrogen ion.

Thus, we can rewrite as;

Ka1 = [[H+] × [H+]]/(H2S)

Ka1 = (H+)²/(H2S)

Concentration of H2S is given as 0.1M. Thus;

8.9 × 10^(-8) = (H+)²/0.1

(H+)² = 0.1 × 8.9 × 10^(-8)

(H+) = √(0.1 × 8.9 × 10^(-8))

(H+) = 0.00009433981

Now, PH is gotten from;

PH = -log (H+)

Thus;

PH = -log 0.00009433981

PH ≈ 4.0

Answer:

C

Explanation:

Complete Question

You are given a solution containing a pair of enantiomers (A and B). Careful measurements show that the solution contains 98% A and 2% B. What is the enantiomeric excess?

Answer:

The value is  [tex]k  = 96 %[/tex]

Explanation:

From the question we are told that

   The  percentage of  enantiomer A is  A =  98%

    The  percentage of  enantiomer B is  B =  2%

Generally the enantiomeric excess is mathematically represented as

      [tex]k  =  \frac{A -B}{A+B}  *  100[/tex]

=>   [tex]k  =  \frac{98 -2}{98+2}  *  100[/tex]

=>   [tex]k  = 96 %[/tex]

Answer:

4

Explanation:

24/6 is 4.

Answer:

Mathematically: D = m/v. If you know what liquid you have, you can look up its density in a table. Once you know that, all you have to do to find the mass of the liquid is to measure its volume. Once you know density and volume, calculate mass using this relationship: mass = density • volume.

Explanation:

Answer:

it is Calcium (Ca)

4th period, 2nd group, 2 valence electrons

Answer:

Several extractions is more effective than a single extraction.

Explanation:

When extraction is carried out multiple times, for instance, in this case, the extraction was carried out with three portions of the solvent rather than with just a single portion of the solvent, the amount of material left in the residue will be lower, because the extraction is more complete.

Several extractions with smaller volumes of solvent are more effective than a single extraction with a large volume of solvent.

Answer:

I think it's A and D

Explanation:

I'm not sure if it's right

Answer:

The answer is B and D

Explanation:

trust fr

Answer:

Exothermic

Explanation:

Nuclear fission means splitting, so there is a lot of energy being released.

Answer:

polar bonds are caused by different kind of atoms, because almost every atoms have different powers to attract electrons.

the answer will be the two same atoms, F2

Answer:

See explanation

Explanation:

When the temperature was increased, the pressure of the gas in the can was increased.

When Maria removed the can and placed it in cold liquid, the decrease in temperature led to a corresponding decrease in pressure of the gas inside the can hence the can was crushed.

Hypothesis: The pressure of the gas in the can is directly proportional to temperature.

Maria was careless about the experiment. She ought to have first checked whether the hot plate was off before placing the soda can. Secondly,she should not have immediately plunged the soda can into liquid because it will shrink due to decrease in pressure. She should not also have removed the soda can with bare hands to avoid getting burns and blisters.

Calcium (Ca) is in group 2 and period 4 on the periodic table be because Calcium has 2 valence electrons and 4 electron shell. Thus, calcium is a metal like all other group 2 element.

The correct answer to the question is Option C. Calcium, like all group 2 elements, is reactive and a solid at room temperature.

Calcium is a group 2 element majorly because it has 2 valence electrons. It is also in period 4 because it has 4 electron shells.

Being a group 2 element, calcium is a solid at room temperature and also reactive. All elements in the group 2 are metals.

There are other elements in period 4 which are not solid. For example krypton is an element in period 4 and it is a gas and not reactive.

From the above information, we can conclude that the correct answer to the question is:

Option C. Calcium, like all group 2 elements, is reactive and a solid at room temperature.

See attached image

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Answer:

Explanation:

Significant figure implies number of digits that are to be considered. Some rules are required to be considered when writing a given expression to an expected significant figures.

So that:

1) 0.00004050 is 4 significant figures

2) 54.7000 is 6 significant figures

3) 1,000.09 is 6 significant figures

4) 0.039 is 2 significant figures

Answer:

K₂ = 1.12s⁻¹

Explanation:

Based on Arrhenius equation:

ln K₂/K₁ = -Ea/R (1/T₂ - 1/T₁)

Where K is rate constant,

R is gas constant (8.314J/molK),

T is absolute temperature (In K) Of 1, initial state and 2, final state.

ln K₂/K₁ = -Ea/R (1/T₂ - 1/T₁)

ln K₂/2.10x10⁻²s⁻¹ = -82000J/mol/8.314J/molK (1/(273.15 + 58) - 1/(273.15 + 19))

ln K₂ / 2.10x10⁻²s⁻¹ = 3.976

K₂ / 2.10x10⁻²s⁻¹ = 53.3

Answer:

a. 0.183 mol C

b. 0.366 mol H

Explanation:

Assuming total combustion, all of the carbon in the unknown compound turned into carbon dioxide, CO₂.

So first we calculate the CO₂ moles produced, using its molecular weight:

This means in the unknown compound there were 0.183 moles of carbon, C.

Conversely, all of the hydrogen in the unknown compound turned into water, H₂O.

Calculating the H₂O moles:

We multiply the water moles by two, as there are 2 H moles per H₂O mol:

Answer:

Percent error

Explanation:

Percent error is defined as the percentage of the difference between the measured( accurate value) and the known value of a substance.

It is usually calculated by:

Measured value — Known value/ known value * 100%

Percent error is the calculated value that is used to evaluate accuracy for a set of data

Answer:

2.35 x 10²⁰ atoms Ga

Explanation:

After converting from mg to g, use the molar mass as the unit converter to convert to moles. Then using Avogadro's number, 6.022 x 10²³ convert from moles to atoms of Ga.

[tex]27.2mgGa*\frac{1g}{1000mg} *\frac{1 mol Ga}{69.72gGa} *\frac{6.022*10^2^3 atoms Ga}{1 molGa} = 2.349 * 10^2^0 atoms Ga[/tex]

Then round to 3 significant figures = 2.35 x 10²⁰ atoms Ga.

The number of atoms in 27.2 mg sample of Ga is 2.35 × 10²⁰ atoms

From the question, we are to calculate the number of atoms in a 27.2 mg sample of Ga.

First, we will determine the number of moles of Ga present

Using the formula,

[tex]Number\ of\ moles = \frac{Mass}{Molar\ mass} [/tex]

Mass = 27.2 mg = 0.0272 g

Molar mass = 69.72 g/mol

Then,

[tex]Number\ of\ moles \ of\ Ga = \frac{0.0272}{69.72} [/tex]

[tex]Number\ of\ moles \ of\ Ga = [/tex] 0.000390132 moles

Now, for the number of atoms present

From the formula

Number of atoms = Number of moles × Avogadro's constant

Then,

Number of Ga atoms = 0.000390132 × 6.022×10²³

Number of Ga atoms = 2.35 × 10²⁰ atoms

Hence, the number of atoms in 27.2 mg sample of Ga is 2.35 × 10²⁰ atoms

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