Describe the procedure Bourouiba uses to study sneezes.

Answer:

Equilibrium shifts left making more NO2

Explanation:

In Le Chatlier's Principle,  increase in volume  shifts equilibrium to side with more moles so... there's 2 moles on left and 1 mole on right, so equilibrium shifts to left making more NO2

According to chemical equilibrium and Le-Chatlier's principle , the equilibrium will shift to left with increase in concentration of NO₂.

Chemical equilibrium is defined as the condition which arises during the course of a reversible chemical reaction with no net change in amount of reactants and products.A reversible chemical reaction is the one wherein the products as soon as they are formed react together to produce back the reactants.

At equilibrium, the two opposing reactions which take place take place at equal rates and there is no net change in amount of the substances which are involved in the chemical reaction.At equilibrium, the reaction is considered to be complete . Conditions which are required for equilibrium are given by quantitative formulation.

Factors which affect chemical equilibrium are change in concentration , change in pressure and temperature and presence of catalyst.

Learn more about chemical equilibrium,here:

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Answer:

1L

Explanation:

Data obtained from the question include:

Initial volume (V1) = 25L

Initial temperature (T1) = 12750°C

Final temperature (T2) = 250°C

Final volume (V2) =..?

Next we shall convert from celsius to Kelvin temperature. This is illustrated below:

T(K) = T(°C) + 273

Initial temperature (T1) = 12750°C

Initial temperature (T1) = 12750°C + 273 = 13023K

Final temperature (T2) = 250°C

Final temperature (T2) = 250°C + 273 = 523K

Finally, we can obtain the new volume of the gas by using Charles' law equation as shown below:

V1/T1 = V2/T2

25/13023 = V2/523

Cross multiply to express in linear form

13023 x V2 = 25 x 523

Divide both side by 13023

V2 = 25 x 523 / 13023

V2 = 1L

Therefore, the new volume of the gas is 1L.

The volume of this gas after it cools to 250°C is equal to 0.490 Liter.

Given the following data:

To determine the volume of this gas after it cools to 250°C, we would apply Charles's law:

Mathematically, Charles law is given by the formula;

[tex]\frac{V}{T} =k\\\\\frac{V_1}{T_1} = \frac{V_2}{T_2}[/tex]

Where;

Substituting the given parameters into the formula, we have;

[tex]\frac{25}{12750} = \frac{V_2}{250} \\\\25 \times 250 = 12750V_2\\\\6250 = 12750V_2\\\\V_2 = \frac{6250}{12750}[/tex]

Final volume = 0.490 Liter.

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Answer:  B. 1.58 x 10 ∧ -10 mol/dm3 of OH- ions

Explanation:

pOH = - log [OH-]

It is well known that; pH + pOH = 14

That is to say; 4.2 + pOH = 14, therefore; pOH = 14 - 4.2 = 9.8

9.8  = - log [OH-]

In other to get the concentration, we take the anti-log of 9.8 .

Anti-log of 9.8 = 1.58 x 10 ∧ -10mol/dm3.

Answer:

Explanation:

According to hooks law "provide the elastic limit of an elastic material is not exceeded the extension e is directly proportional to the applied force F"

[tex]F= ke[/tex]

where F= applied force

           k= spring constant

           e= extension

Given data

length of string l = 16cm

extension  e = 20-16= 4cm

applied force = 5N

we need t o first calculate the spring constant k

apply the formula

[tex]F= ke[/tex]

[tex]5=k*4\\k= \frac{5}{4} \\k= 1.25N/cm[/tex]

we can now calculate the extension of the string when supporting a 6N weight

[tex]F= ke\\6=1.25*e\\e= \frac{6}{1.25} \\e= 4.8cm[/tex]

The length of the string when supporting a 6N weight is

[tex]= length+ extension\\= 16+4.8\\= 20.8cm[/tex]

COMMENT :According to the analysis an extra  weight of 1N will cause add 0.8cm to the length of the string

Answer:

A theory doesn’t change into a scientific law because of new or better evidence.

Explanation:

A theory will always remain a theory, and i law will remain a law. The reason being that theories and laws may differ on account of newfound countervailing evidence. Remember, theories and laws are very different from hypotheses.

Answer:

1s2 2s2 2p6 3s2 3p6 4s1

Explanation:

Aufbau's principal of the arrangement of electronic configuration states that, electrons fill orbitals of lower energy first before the higher energy. 1s2 2s2 2p6 3s2 3p6 4s2 3d10...

This arrangement explains the Aufbau's principal, hence, or therefore, the 1s2 2s2 2p6 3s2 3p6 4s1 is the right answer for the representation of the electron configuration for potassium (K).

hope this was helpful!

Answer:

The correct option is;

D. Petrol  > Alcohol > Kerosene oil > Water

Explanation:

The volatility of a liquid is a measure of how readily it evaporates or vaporizes such that a volatile liquid will evaporate and be present as a vapor at a given temperature or pressure than a less volatile liquid

The volatility of a liquid is directly related to the liquid's vapor pressure such that the higher the vapor the more volatile the liquid

The Reid vapor pressures of the given liquids are as follows;

Alcohol (Ethanol)= 17-55 kPa

Petrol = 53-60 kPa

Kerosene Oil= 6.8 kPa

The vapor pressure for water at 37.8°C = 6.6 kPa

Therefore, the correct order evaporation is as follows, starting from the highest vapor pressure to the lowest;

Petrol  > Alcohol >  Kerosene Oil > Water.

Answer:

bromine (Br)

Explanation: Iron enters into a reaction with substances of different classes, and interacts with oxygen, carbon, phosphorus, halogens (bromine, iodine, fluorine and chlorine), and also nitrogen. These are not all the reactions of iron – this metal reacts with many elements.

Answer: The volume of the gas when the temperature of the gas is raised to [tex]125^0C[/tex] is 363 ml

Explanation:

To calculate the final volume of the system, we use the equation given by Charles' Law. This law states that volume of the gas is directly proportional to the temperature of the gas at constant pressure.

Mathematically,

[tex]\frac{V_1}{T_1}=\frac{V_2}{T_2}[/tex]

where,

[tex]V_1\text{ and }T_1[/tex] are the initial volume and temperature of the gas.

[tex]V_2\text{ and }T_2[/tex] are the final volume and temperature of the gas.

We are given:

[tex]V_1=281ml\\T_1=35.0^oC=(35.0+273)K=308K\\V_2=?\\T_2=125^0C=(125+273)K=398K[/tex]

Putting values in above equation, we get:

[tex]\frac{281}{308}=\frac{V_2}{398}\\\\V_2=363ml[/tex]

Thus the volume of the gas when the temperature of the gas is raised to [tex]125^0C[/tex] if the pressure remains constant is 363 ml

Answer:

If the weight of chemical is same so it represent that the experiment is valid.

Explanation:

If Bronwyn performed the same chemical reaction four times and she measure the weight of chemical with the help of electrical weight balance so if she find out the weight of the chemical that is produced during four experiments then we can say that the experiment is valid because the experiment was performed four times and that is enough for validation of the experiment.

Answer:

Melting point

Explanation:

Answer:

Melting point

Explanation:

When a solid turns into a liquid, it is melting.  Therefore, it is the melting point.

Answer:

Carbon is the only element having the ability to form large numbers of compounds because carbon atom has four electrons in its valence shell and can share not only one but more electrons with other atoms and can form four chemical bonds  which results into huge number of hydrocarbons.

Different types of hydrocarbons are:

Methane - it has only one carbon bounded with four hydrogen atoms with single bond and have chemical formula CH4.

Ethane: it has two carbon atoms attached with single bond and bounded with three hydrogen atoms each with single bond and have chemical formula C2H6.

Ethene: it has two carbon atoms attached with double bond and bounded with two hydrogen atoms each with single bond and have chemical formula C2H4.

Butyne: it has four carbon atoms, two of which are attached with triple bond and rest electrons are attached with hydrogen atoms and have chemical formula C4H6.

Hence, carbon  is able to form such a large number of compounds.

Answer:

Option d is correct

Explanation:

The basis of the VSEPR model of molecular bonding is that to minimize repulsions, electron domains in the valence shell of an atom arrange on their own.

According to VSEPR theory, if there are two electron domains on a central atom, they will be arranged such that the angles between the domains are 180°

Answer:

Atomic number is the number of protons in an atom

Atomic mass is the mass of an atom.

Explanation:

which of the following is the best choice for presenting the relationship between atomic number and atomic mass?

Atomic number is the number of protons in an atom

Atomic mass is the mass of an atom.

Answer:

b) Inductive Reasoning

Explanation:

Answer:

The answer is A.

Explanation:

When acid react with metal carbonate, it will form salt, water and carbon dioxide.

For example :

HCl + CaCO3 → CaCl + H2O + CO2

Answer: 6.022×10²³ molecules Oxygen

Explanation:

To get molecules, you will need Avogadro's number.

Avogadro's number: 6.022×10²³ molecules/mole

[tex]1mol O *\frac{6.022*10^2^3molecules }{1mol} =6.022*10^2^3 molecules[/tex]

Answer:

6.022 x 10^23 molecules

Explanation:

Answer:

Approximately [tex]0.20\; \rm L[/tex].

Explanation:

Convert the temperature of this gas to absolute temperature:

[tex]T = 25\; \rm ^\circ C \approx (25 + 273.15)\; \rm K = 298.15\; \rm K[/tex].

Let [tex]P[/tex] and [tex]V[/tex] represent the pressure and volume of this gas, respectively. Let [tex]n[/tex] represent the number of gas particles in this gas. Let [tex]R[/tex] represent the ideal gas constant. By the ideal gas law:

[tex]P \cdot V = n \cdot R \cdot T[/tex].

For this question:

Look up the ideal gas constant [tex]R[/tex] that takes [tex]\rm atm[/tex] as the unit for pressure:

[tex]R \approx 0.082057\; \rm L \cdot atm \cdot K^{-1}\cdot mol^{-1}[/tex].

This question is asking for [tex]V[/tex], the volume of this gas. Rearrange the ideal gas equation and solve for [tex]V[/tex]:

[tex]\begin{aligned} V &= \frac{n \cdot R \cdot T}{P} \\ &\approx \frac{0.00831\; \rm mol\times 0.0082057\; \rm L \cdot atm \cdot K^{-1}\cdot mol^{-1}\cdot 298.15\; \rm K}{1.01\; \rm atm} \\ &\approx 0.0020\; \rm L\end{aligned}[/tex].

Answer:

Hydrogen

Explanation:

A reducing agent is a substance which gives up its electrons to become oxidized. Generally, metals are oxidized (reducing agents) while non-metals are reduced (oxidizing agents).

However, hydrogen which is a non-metal is usually oxidized in the presence of stronger oxidizing non-metals such as fluorine and oxygen.

Hydrogen thus, acts as a reducing agent by giving up its electrons to become oxidized. Even though among all non-metals, Hydrogen has the greatest potential to be oxidized, it is a poor reducing agent compared to reactive metals.

Answer:

iron

Explanation:

rust is an oxide of iron

Answer:

A natural gas stove converts chemical energy from burning into thermal energy used to cook food.

Answer:

the answer to this question is hydrogen gas

Answer: B

Explanation:

To find the amount of heat required, you would use q=mcΔT.

[tex]q=2g(4.18J/g°C)(68-34°C)[/tex]

q=284.2 J

*Please ignore the capital A in the equation. I can't find a way to type in the degree sign into the equation without the A appearing.

Answer: thermal equilibrium

Explanation: the temperature increased only when all of the water was in one phase.

Answer:

737.52 mL de agua

Explanation:

En este caso solo debes usar la expresión de molaridad de una solución la cual es:

M = moles / V

Donde:

V: Volumen de solución.

Como queremos saber la cantidad de agua, queremos saber en otras palabras cual es la cantidad de solvente que se utilizó para preparar los 800 mL de disolución.

Una disolución se prepara con un soluto y solvente. El soluto lo tenemos, que es el nitrato de plata. Con la expresión de arriba, calculamos los moles de soluto, y luego su masa. Posteriormente, calculamos el volumen con la densidad, y finalmente podremos calcular el solvente de esta forma:

V ste = Vsol - Vsto

Primero calcularemos los moles de soluto:

moles = M * V

moles = 2 * 0.800 = 1.6 moles

Con estos moles, se calcula la masa usando el peso molecular reportado que es 169.87 g/mol:

m = moles * PM

m = 1.6 * 169.87 = 271.792 g

Ahora usando el valor de la densidad, calcularemos el volumen de soluto empleado:

d = m/V

V = m/d

V = 271.792 / 4.35

V = 62.48 mL

Finalmente, la cantidad de agua necesaria es:

V agua = 800 - 62.48

V agua = 737.52 mL

Explanation:

300c = 1.8f+32= please calculate it yourself ☺

300c= k+273= 573k

Answer:

Explanation:

The innate immune system is a defense system with which we are all born and which protects us at all times against all antigens, prevents harmful external bodies from entering our body.

The acquired immune system is the second line of defense and develops by exposing itself to various antigens, building a defense against it when the innate system cannot fight the invader.

Answer:

Part A. The Innate immune system

Part B. The adaptive (or active) immune system

Explanation:

The immune system refers to the organs, tissues cells and proteins which work together to protect the body from harmful invaders that cause disease such as micro-organisms like viruses, bacteria, etc.

Organs and tissues that form part of the immune system include the thymus and bone marrow, lymph nodes and vessels, spleen, and skin.

The main immune cells are the white blood cells, also called leukocytes. Some types of white blood cells, called phagocytes engulf invading organisms. Others called lymphocytes  help the body remember the invaders and destroy them.  The two kinds of lymphocytes are B lymphocytes and T lymphocytes, whose name depend on where they mature. Lymphocytes start their life in the bone marrow and either stay there and mature into B cells, or go to the thymus gland to mature into T cells.

The immune system consists of two main parts or system.