Será lançado na próxima quarta-feira, 1º de julho, em São Bernardo do Campo (SP), o primeiro ônibus brasileiro a hidrogênio. [...] O projeto Ônibus Brasileiro à Célula Combustível a Hidrogênio é o ponto de partida para o desenvolvimento de uma solução mais limpa para o transporte público urbano no Brasil. (Disponível em: Acesso em: 19 out. 2009.) Quanto aos processos químicos envolvidos na produção de energia elétrica em células de combustíveis a partir do oxigênio e do hidrogênio, é correto afirmar:

Answers

Answer 1
Sera bu they are going there for fun

Related Questions

help me with this attachment please​

Answers

Answer:

See explanation

Explanation:

Let us recall that the basic rule in writing balanced chemical reaction equations is that the number of atoms of each element on the right hand side of the reaction equation is the same of the number of atoms of the same element on the left hand side of the reaction equation.

The reaction of red hot iron and steam is written as follows;

3Fe + 4H2O → Fe3O4 + 4H2.

The decomposition reaction of ammonium dichromate is written as;

(NH4)2Cr2O7 → N2 + Cr2O3 + 4H2O

Reaction of aluminium, sodium hydroxide and water is as follows,

2Al + 2NaOH + 2H2O ----> 2NaAlO2 + 3H2

Reaction of potassium bicarbonate with sulphuric acid;

2KHCO3 + H2SO4 -------> K2SO4 + 2H2O + 2CO2

Reaction of zinc and sodium hydroxide is as follows;

Zn + 2NaOH→Na2ZnO2 + H2

Why is sodium an active metal

Answers

Answer:

Sodium is very reactive in nature. When exposed in air, it automatically forms Na2O. When it is put in water it reacts vigorously and starts burning on water. Due to the above reasons Sodium is called an active metal

Explanation: hope this helps pls mark as brainliest ty

I have oxygen gas at 2 L and 2 atm. At what pressure is the oxygen gas if my volume decreases to 1 L?

Answers

Answer: The oxygen gas has a pressure of 4 atm if my volume decreases to 1 L.

Explanation:

Given: [tex]V_{1}[/tex] = 2 L,        [tex]P_{1}[/tex] = 2 atm

[tex]V_{2}[/tex] = 1 L,          [tex]P_{2}[/tex] = ?

Formula used to calculate the new pressure is as follows.

[tex]P_{1}V_{1} = P_{2}V_{2}[/tex]

Substitute the values into above formula as follows.

[tex]P_{1}V_{1} = P_{2}V_{2}\\2 atm \times 2 L = P_{2} \times 1 L\\P_{2} = 4 atm[/tex]

Thus, we can conclude that the oxygen gas has a pressure of 4 atm if my volume decreases to 1 L.

Which reaction will most likely take place based on the activity series? Li > K Ba CaNa > Mn > Zn > Cr> Fe> Cd Ni > H > Sb > Cu > Ag > Pd > Hg > Pt a. Ag+FeCl 3 b, Zn + CaO C. Ba+Na 2 CO 3 d . Cr+KNO3

Answers

Answer:

Among the given reactions,

a. Ag+FeCl 3

b, Zn + CaO

C. Ba+Na 2 CO 3

d . Cr+KNO3

which reaction is likely to take place based on the reactivity series?

Explanation:

The metal reactivity series is:

Li > K> Ba >Ca>Na > Mn > Zn > Cr> Fe> Cd Ni > H > Sb > Cu > Ag > Pd > Hg > Pt

The highly reactive metal will displace the less reactive metal from its compound during a displacement reaction.

a. Ag+FeCl 3

Ag is less reactive than Fe, so Ag cannot displace Fe from its compound.

This reaction also does not occur.

b, Zn + CaO

Zn is less reactive than Ca, so it cannot displace Ca from its compound.

This reaction does not occur.

C. Ba+Na 2 CO 3

Ba is more reactive than Na, so Ba displaces Na from its compound.

This reaction is possible.

d . Cr+KNO3

Cr is less reactive than K, so it cannot displace K from its compound.

Hence, This reaction is not possible.

Answer:

option c) Ba+Na 2 CO 3 -> BaCO3 +2Na

Answer:

C. Ba+Na 2 CO 3 -> BaCO3 +2Na

Which group on the periodic table contains chemical elements that are shiny and conduct electricity?
A.
Metalloids
B.
Nonmetals
C.
Representative elements
D.
Metals

Answers

D. Metals
Elements that are shiny, solid, conducts electricity, has atomic mass of 108 is metal.

KHP, the acid used in this experiment,
stands for potassium hydrogen
phosphorous.
True
False

Answers

Answer:

false

Explanation:

standard form is Potassium hydrogen phthalate

If 3.02 g of CuNO3 is dissolved in water to make a 0.560 M solution, what is the volume of the solution in milliliters?

Answers

Answer: The volume of the solution is 28.75 mL

Explanation:

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L. The formula used to calculate molarity:

[tex]\text{Molarity of solution}=\frac{\text{Given mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (mL)}}[/tex] .....(1)

Given values:

Molarity of copper nitrate = 0.560 M

Given mass of copper nitrate = 3.02 g

Molar mass of copper nitrate = 187.56 g/mol

Putting values in equation 1, we get:

[tex]0.560=\frac{3.02\times 1000}{187.56\times \text{Volume of solution}}\\\\\text{Volume of solution}=\frac{3.02\times 1000}{187.56\times 0.560}=28.75mL[/tex]

Hence, the volume of the solution is 28.75 mL

rare earth elements plz

Answers

Answer:

Rare earth elements are lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium - that appear in low concentrations in the ground.

Explanation:

The rare earth elements (REE) are a set of seventeen metallic elements. These include the fifteen lanthanides on the periodic table plus scandium and yttrium. Rare earth elements are an essential part of many high-tech devices.

Subtract to find the temperature changes

for the water and the metal.

Answers

Answer:

???what metal????????????

What is meant by term valency? Explain it in terms of electrons donations and acceptance.​

Answers

Answer:

Valency can be defined as a measure of the combining power of a chemical element with other atoms to form a molecule or chemical compound.

Explanation:

An atom can be defined as the smallest unit comprising of matter that forms all chemical elements. Thus, atoms are basically the building blocks of matters and as such determines or defines the structure of a chemical element.

Generally, atoms are typically made up of three distinct particles and these are protons, neutrons and electrons.

In Chemistry, electrons can be defined as subatomic particles that are negatively charged and as such has a magnitude of -1.

Valence electrons can be defined as the number of electrons present in the outermost shell of an atom. Valence electrons are used to determine whether an atom or group of elements found in a periodic table can bond with others. Thus, this property is typically used to determine the chemical properties of elements.

Valency can be defined as a measure of the combining power of a chemical element with other atoms to form a molecule or chemical compound.

Typically, valency is measured by the amount of hydrogen atoms that a chemical element can combine with or displace to form a molecule or chemical compound.

For example, Oxygen has a total number of eight (8) electrons while neon has total number of ten (10) electrons. Therefore, an atom of oxygen is able to gain (accept or receive) two (2) more electrons in order to have the same electron arrangements as the noble gas i.e an atom of neon with an atomic number of 10.

Please help please help

Answers

Answer:

sry I don't know much about chemistry

Its 60.7% because the total mass of NaCl is 58.5g and chlorine only costitute of the 35.5g. So its mas of chlorine over total mass x 100

Why do we need to know these organic molecules?
Are they important to living things?​

Answers

Answer:

Organic molecules are important to living things because life is based on the properties of carbon.

Properties of Carbon

Carbon is an important element because it can form four covalent bonds.

Carbon skeletons can vary in length, branching, and ring structure.

The carbon skeletons contain the functional groups that are involved in biochemical

Explanation:

Hope it helps

Figure 1 (Use this figure to answer questions 6,7, and 8. Assume that the height at point
A and point C are the same)
С
B
As the car moves from point A, to point B, and finally to point C, the total energy of the car
decreases from point A to point B, then increases from point B to point
increases from point A to point B, then decreases from point B to point
O is lost between points B and C
stays the same, but is converted between potential and kinetic energy

Answers

Answer:

JWBVH

Explanation:

NWSBWHSBHS

Which two of the following changes of state involve solids?
Select two (2) answers


A. melting

B. boiling

C. freezing

D. evaporating

Answers

Answer:

Answer is A... Melting and freezing

An oxygen atom has 8 protons. What number of neutrons would make an
oxygen atom most stable?

A. 10
B. 6
C. 12
D. 8

Answers

D. 8

Hope this helps! :)

______________

Answer:

D: 8 neutrons would make it most stable

Please help me with this in the picture I need 8 thing wrong and 8 what should they do right

Answers

1- savannah shouldn’t drink that toxic stuff
2- scissors shouldn’t be in the charger hole
3- there shouldn’t be a snake in the lab
4- lindsey should pay attention to what’s in front of her
5- freddy shouldn’t steal stuff
6- there shouldn’t be a plug in the water
7- evan shouldn’t drink anything in the lab
8- there shouldn’t be food in the lab

Please I need an explanation on the relationship between concentration and volume of reacting substances​

Answers

Answer:

when d volume of a substance is high, the concentration is gonna b low...

Jus lyk putting much water in just a cube of sugar

Explanation:

So lower volume, higher concentration

The absorption spectrum of sodium has a line at 589 nm. What is the energy of this line? (The speed of light in a vacuum is 3.00 x 10^8 m/s, and Planck's constant is 6.626 x 10^-34 Jos.)

A. 8.89 x 10^26 J
B. 5.09 x 10^14 J
C. 3.37 x 10^-19 J
D. 2.96 x 10^18 J

Answers

Answer:

C. 3.37 x 10^-19 J

Explanation:

Why does platinum metal make a good catalytic surface for reactant molecules?
It causes reactant molecules to be less reactive.
It strengthens bonds between reactant molecules.
It prevents products from breaking away from the surface.
It holds reactant molecules in a good position for them to react.

Answers

Answer:

it holds reactant molecules in a good position for then to react

Answer:

D. It holds reactant molecules in a good position for them to react.

Explanation:

Got a 100 on e2020.

A student wants to make a 0.600 M aqueous solution of barium sulfate, BaSO4, and has a bottle containing 12.00 g of barium sulfate. What should be the final volume of the solution?


Find the numerical answer for this question and make sure to include the following:


What is the formula for molarity?

What is the molar mass for barium sulfate?

When you give your numerical answer, what are the correct significant figures and how do you know that is the correct amount?

Need this ASAP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Answers

Answer: The volume of the solution is 85.7 mL

Explanation:

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L. The formula used to calculate molarity:

[tex]\text{Molarity of solution}=\frac{\text{Given mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (mL)}}[/tex] .....(1)

We are given:

Molarity of solution = 0.600 M

Given mass of [tex]BaSO_4[/tex] = 12.00 g

We know, molar mass of [tex]BaSO_4=[(1\times 137.33)+(1\times 32.07)+(4\times 16)]=233.4g/mol[/tex]

Putting values in equation 1, we get:

[tex]0.600=\frac{12.00\times 1000}{233.4\times \text{Volume of solution}}\\\\\text{Volume of solution}=\frac{12.00\times 1000}{233.4\times 0.600}=85.68mL=85.7mL[/tex]

The rule of significant number that is applied for the problems having multiplication and division:

The least number of significant figures in any number of the problem determines the number of significant figures in the answer.

Here, the least number of significant figures is 3 that is determined by the number, 0.600. Thus, the answer must have these many significant figures only.

Hence, the volume of the solution is 85.7 mL

A molecule has four bonded atoms around a central atom. The central atom does not have any lone pairs of electrons. What is the geometry of the molecule?

Answers

Answer:

Tetrahedral. Tetra- signifies four, and -hedral relates to a face of a solid; “tetrahedral” literally means “having four faces. ” This shape is found when there are four bonds all on one central atom, with no lone electron pairs. In accordance with the VSEPR theory, the bond angles between the electron bonds are 109.5o ...

There are two characteristics of molecules, one is geometry and other is shape. Shape is excluding lone pair surrounding the central element and geometry is including the lone pair. Therefore, the geometry of given molecule is tetrahedral.

What is VSEPR theory?

VSEPR stands for valence shell electron pair repulsions. VSEPR theory is used to predict the shape and geometry of molecules on the basis of valence electrons pairs that are present around the central element of the molecule.

According to VSEPR theory, Lone pair lone pair repulsion is greater than bond pair bond pair repulsion. There are so many limitations of VSEPR theory. There is a repulsion between bond pair electrons and lone pairs present on the central element.

A molecule has four bonded atoms around a central atom. The central atom does not have any lone pairs of electrons. The geometry of such molecule is Tetrahedral. Geometry does not include lone pair on central atom.

Therefore, the geometry of given molecule is tetrahedral.

To know more about VSEPR theory, here:

https://brainly.com/question/19582124

#SPJ6

The values used in the scale of pH and pOH are derived from a system designed by ______.

Curie
Gordonsen
Dalton
Sorenson

Answers

the answer to this question Is sorenson

In what way are electrons quantized?
O A. They have fixed energy values.
they
OB. They can be gained and lost.
O C. They are negatively charged.
O D. They form bonds in molecules.

Answers

Answer: The correct option is A) They have fixed energy values.

Explanation:

Electron is one of the sub-atomic particle present around the nucleus of an atom which is negatively charged.

In an atomic model, it is assumed that the electron revolves around the nucleus in discrete orbits having fixed energy levels.

These electrons when jumping from one energy level to another, some amount of radiation is either emitted or absorbed.

These fixed energy levels are given by the Bohr model and thus, the electrons are quantized.

Hence, the correct option is A) They have fixed energy values.

Answer: They have fixed energy values

Explanation: a pex

NO2 + H2O =
SO2 + H2O =
H2S + H2O=

Answers

SO2+ H2O=H2SO3

H2S+ H2O=H2SO4 +H2

NO2+  H2O= HNO3+NO

State the name(s) of the sub-atomic particle(s) that have/has a positive charge. Answer with the name of the particle(s) only.

A. Neurons
B. Protons
C. Electrons

Answers

Protons hope this helps

Answer:

protons because they have the most positive charge

Can someone please solve this for me and explain it

Answers

83.3% yield

Explanation:

First, we need to convert 240 g of [tex]Fe_{2}O_{3}[/tex] into moles:

[tex]240 \:g \:Fe_{2}O_{3} \:\times(\frac{1\:\text{mol}\:Fe_{2}O_{3}}{159.69\: \text {g}\:Fe_{2}O_{3}})[/tex]

[tex]=1.50 \:\text{mol}\:Fe_{2}O_{3}[/tex]

Next, find the theoretical Fe yield using molar ratios.

[tex]1.50 \: \text {mol} \: Fe_{2}O_{3}\: \times (\frac{2\: \text{mol} \: Fe}{1 \:\text{mol} \: Fe_{2}O_{3}})[/tex]

[tex] = 3.00 \: \text{mol} \: Fe[/tex]

Then convert this back into grams:

[tex]3.00 \: \text{mol} \:Fe \times (\frac{55.845 \: \text{g} \: Fe}{1 \: \text{mol} \: Fe}) = 168 \: \text{g} \: Fe[/tex]

Note that actual yield is only 140 g Fe so percentage yield is

[tex]\dfrac{140\:\text{g}\:Fe}{168\:\text{g}\:Fe} \times 100[/tex]%= 83.3%

83.3%

The answer is 83.3%

BRAINILIEST PLEASE

Which diagram shows how the covalent bonds most likely form in a phosphorous trichloride molecule?

Answers

The first answer is correct

The first diagram shows the covalent bonds most likely form in a phosphorous trichloride molecule. Hence, option A is correct.

What is a covalent bond?

Covalent bonds can be polar or nonpolar depending on the electronegativity difference between the atoms involved. In a nonpolar covalent bond, the electrons are shared equally between the atoms. In a polar covalent bond, the electrons are shared unequally.

Phosphorus trichloride (PCl₃) is a covalent compound that consists of one phosphorus atom and three chlorine atoms. The three chlorine atoms are located in a plane that is perpendicular to the phosphorus atom, forming an equilateral triangle with bond angles of 120°.

The molecule has a trigonal pyramidal shape, with the phosphorus atom at the apex and the three chlorine atoms at the base of the pyramid. The fourth hybridized orbital of phosphorus contains a lone pair of electrons that is located above the trigonal plane, giving the molecule a distorted tetrahedral geometry.

Thus, option A is correct.

To learn more about the covalent bond, follow the link:

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ChemBonding9. In ammonium chloride NH4Cl, the bonding between NH4+ and chloride ion Cl− is _______.
options:

ionic
polar covalent
nonpolar covalent

Answers

So NH4Cl has ionic bond between NH4+ and Cl-, hydrogen bond (can be considered covalent bond too and N and H are both non metals and covalent bonds occur between non metals) between N and H in NH4 and covalent bond between NH4 and another NH4.

Which of the following acids has a basicity of 2?
1 point
ethanoic acid
hydrochloric acid
nitric acid
sulphuric acid

Answers

Answer:

its answer is nitric acid...

this may help you...

How do the Carnivorous plants survive without soil?

Answers

Answer:

Carnivorous plants are easy to grow, if you follow a few, simple rules.

Wet all of the time.
Mineral-free water.
Mineral-free soil.
Lots of light.


Wet all of the time.
Carnivorous plants are native to bogs and similar nutrient-poor habitats. As a consequence, the plants live in conditions that are constantly damp. To grow healthy carnivorous plants, it is important to duplicate their habitat as closely as possible. Keep the soil wet or at least damp all of the time. The easiest way to do this is use the tray method. Set the pots in a tray or saucer, and keep water in it at all times. Pitcher plants can grow in soggy soil with the water level in the saucer as deep as 1/2 the pot, but most carnivorous plants prefer damp to wet soil, so keep the water at about 1/4 inch and refill as soon as it is nearly gone. Water from below, by adding water to the tray, rather than watering the plant. This will avoid washing away the sticky muscilage of the sundews and butterworts and keep from closing the flytraps with a false alarm.


Mineral-free water.
Always use mineral-free water with your carnivorous plants, such as rainwater or distilled water. Try keeping a bucket near the downspout to collect rainwater. Distilled water can be purchased at the grocery store, but avoid bottled drinking water. There are simply too many minerals in it. The condensation line from an air conditioner or heat pump is another source of mineral-free water. Reverse-osmosis water is fine to use. Carnivorous plants grow in nutrient poor soils. The minerals from tap water can “over-fertilize” and “burn out” the plants. In a pinch, tap water will work for a short while, but flush out the minerals with generous portions of rainwater, when it is available.


Mineral-free soil.
The nutrient poor soils to which the carnivorous plants have adapted are often rich in peat and sand. This can be duplicated with a soil mixture of sphagnum peat moss and horticultural sand. Be sure to check the peat label for sphagnum moss. Other types will not work well. The sand should be clean and washed. Play box sand is great, and so is horticultural sand. Avoid “contractor’s sand” which will contain fine dust, silt, clay and other minerals. Never use beach sand or limestone based sand. The salt content will harm the plants. The ratio of the mix is not critical, 1 part peat with 1 part sand works well for most carnivorous plants. Flytraps prefer a bit more sand, and nepenthes prefer much more peat. Use plastic pots, as terra cotta pots will leach out minerals over time and stress your plants.

Explanation:


Kayo na Po bahala magpaigsi

Answer:

A simple answer: Carnivores don't eat plants only flesh. So they would not need soil. But it would be hard for Carnivores to get energy because they get energy indirectly from the animals (herbivores) that they eat. How do they get the energy from a herbivore you might ask. Herbivores eat only plants and that gives the herbivore the plant's energy; but if the herbivore gets eaten, it is indirectly transferred into the Carnivore. Hope this helped!!

Carnivore = only feeds on flesh

Herbivore = eats only plants

Omnivore = eats plants and animals/flesh

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