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Which statement best describes the use of catalytic converters in automobiles? A. They decrease the rate of the reactions that produce harmful gases. B. They oxidize hydrocarbons to form less toxic gases. C. They combine the larger hydrocarbon molecules with smaller ones. D. They increase reaction temperature for cleaner burning.

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Answer:  B. They oxidize hydrocarbons to form less toxic gases.

Explanation:

A catalytic converter is a device which is used in automobile engine to convert the harmful gaseous exhaust into a less toxic pollutant after the process of combustion of the fuel. It conducts an internal redox (oxidation-reduction) reaction in the automobile engine to facilitate such conversion.

On the basis of the above information, They oxidize hydrocarbons to form less toxic gases is the correct option.

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Equations can be balanced by using the half-reaction method. Which step should be completed immediately after finding the oxidation states of atoms? A inserting the coefficients B balancing the half reactions C identifying the half reactions D inspecting the number of atoms

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Equations can be balanced by using the half-reaction method. Which step should be completed immediately after finding the oxidation states of atoms? A inserting the coefficients B balancing the half reactions C identifying the half reactions D inspecting the number of atoms

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Which reactions performed in the experiment involved chemical changes?

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Which reactions performed in the experiment involved chemical changes?

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Can endothermic chemical reactions be spontaneous?

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Can endothermic chemical reactions be spontaneous?

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Chemical reactions such as the decomposition of wastes also occur much faster in warmer water. a. True b. False

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Why do hydrolysis reactions occur more readily in solution than dehydration reactions?

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Why do hydrolysis reactions occur more readily in solution than dehydration reactions?

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Which statement best distinguishes the light-dependent (L-D) reactions from the light-independent (L-IND) reactions? The L-D reactions occur in the thylakoid membrane, and the L-IND reactions occur in the stroma. The L-D reactions occur in the cytoplasm, and the L-IND reactions occur in the chloroplast. The L-D reactions occur in the chloroplast, and the L-IND reactions occur in the mitochondria. The L-D reactions occur in the stroma, and the L-IND reactions occur in the cytoplasm.

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Which statement best distinguishes the light-dependent (L-D) reactions from the light-independent (L-IND) reactions? The L-D reactions occur in the thylakoid membrane, and the L-IND reactions occur in the stroma. The L-D reactions occur in the cytoplasm, and the L-IND reactions occur in the chloroplast. The L-D reactions occur in the chloroplast, and the L-IND reactions occur in the mitochondria. The L-D reactions occur in the stroma, and the L-IND reactions occur in the cytoplasm.

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25. From left to right across a period in the periodic table, elements become less ___________ and more ______________ in their properties. 26. Francium has 36 isotopes, but only francium-223 occurs in nature. Francium-223 spontaneously emits particles and energy, so francium-223 is a(an) _____________ of francium. 27. At sea level, water ______________ at 100°C. 28. Cooking requires continuous addition of energy to the chemical reactions that are taking place. The chemical reactions involved in cooking can be described as __________________. 29. The ________________ theory of matter states that all particles of matter are in constant motion. 30. In Rutherford’s experiments, some of the _______________ aimed at gold atoms bounced back, suggesting that a solid mass was at the center of the atom. 31. You are given the melting points of three unknown substances and are asked to predict which one is an ionic compound. You would select the compound with the ________________ melting point. 32. A flight simulator that helps astronauts prepare for a shuttle launch is an example of a(an) __________________. 33. In the symbol ■([email protected]) He, the superscript 4 is the _________________ for helium, and the subscript 2 is the ___________________ for helium.

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25) Answer is: less metallic and more nonmetallic.

Electronegativity increases from left to right across a period, atoms have tendency to attract electrons.

Electronegativity (χ) is a property that describes the tendency of an atom to attract a shared pair of electrons.

26) Answer is: radioisotope.

Radioisotope has an unstable atomic nucleus and emit energy and particles when it changes to a more stable form.

Francium (Fr) is element with atomic number 87 (87 protons and 87 electrons).

27) Answer is: boils.

Boiling is the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere.

The Celsius scale was based on 0°C for the freezing point of water and 100°C for the boiling point of water at 1 atm pressure.

28) Answer is: endothermic.

There are two types of reaction:  

1) endothermic reaction (chemical reaction that absorbs more energy than it releases, ΔH>0).

2) exothermic reaction (chemical reaction that releases more energy than it absorbs).  

For example, the breakdown of ozone is an endothermic process. Ozone has lower energy than molecular oxygen (O₂) and oxygen atom, so ozone need energy to break bond between oxygen atoms.  

29) Answer is: kinetic.

The average kinetic energy of molecules depends on the temperature.  

As temperature increases, molecules gain more energy from surrounding and move faster.  

Kinetic energy (standard unit is the joule J) depends on speed of the molecule.  

Solid gains kinetic energy to become a liquid and then becomes a gas.

30) Answer is: alpha particles.

This was famous Rutherford’s Gold Foil Experiment: he bombarded thin foil of gold with positive alpha particles.

Rutherford observed the deflection of alpha particles on the photographic film.  

Alpha particles are helium atom particles, consist of two protons and two neutrons.  

According to Rutherford model of the atom: atoms have their charge concentrated in a very small nucleus.  

31) Answer is: highest.

For example, calcium oxide.

Calcium oxide (CaO) has ionic bonds between calcium cations (Ca²⁺) and oxygen anions (O²⁻).

Because it has strong ionic bonds, it has high melting point (around 2600°C).

Ionic bond is the electrostatic attraction between oppositely charged ions (cations and anions).

32) Answer is: a scientific model.

A scientific model is a representation of an idea, an object, a process or a system that is used to describe and explain phenomena that cannot be experienced directly.

33) Answer is: the superscript is mass number and the subscript is atomic number.

Atomic number(Z) is the number of protons, which is characteristic of a chemical element..

Mass number (A) is the total number of protons and neutrons in a nucleus.

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Which of the following reactions is a neutralization reaction? A. ZnCl2(aq) + CaCrO4(aq) → ZnCrO4(s) + CaCl2(aq) B. HNO3(aq) + LiOH(aq) → H2O(l) + LiNO3(aq) C. 2NaOH(aq) + MgCl2(aq) → Mg(OH)2(s) + 2Na+(aq) + 2Cl−(aq) D. 4Fe(s) + 3O2(g) → 2Fe2O3(s)

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Which of the following reactions is a neutralization reaction? A. ZnCl2(aq) + CaCrO4(aq) → ZnCrO4(s) + CaCl2(aq) B. HNO3(aq) + LiOH(aq) → H2O(l) + LiNO3(aq) C. 2NaOH(aq) + MgCl2(aq) → Mg(OH)2(s) + 2Na+(aq) + 2Cl−(aq) D. 4Fe(s) + 3O2(g) → 2Fe2O3(s)

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Which of these reactions is NOT a typical part of the body’s immediate response to stress

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1. The answer is “C”.

“Identical twins” who have been raised apart are typically more similar in intelligence level than biological siblings raised together because they have been born with the same genetic code.

Identical twins originate from a single fertilized egg that parts into two. Before it parts, it is either male or female. After it parts, there are either two guys or two females. The two sections of the fertilized egg embed in the uterus and every create one of the twins.  

Identical twins have the equivalent hereditary source. No immediate reason for monozygotic twinning has been resolved; it isn’t innate. Monozygotic twins speak to around 33% all things considered. They may look strikingly comparative, and it might be hard to reveal to them separated.

2. The answer is “A”.

Lawrence Kohlberg felt that one of the only ways individuals will accomplish the objectives in each of his six stages was to participate in “consensus democracy” in small group settings.

Lawrence Kohlberg felt that the best way to support development through these stages was by discourse of good problems and by investment in consensus democracy inside small groups. Consensus democracy was rule by understanding of the gathering, not larger part rule. This would invigorate and widen the reasoning of youngsters and grown-ups, enabling them to advance starting with one phase then onto the next.

3. The answer is “D.  showing a learner how to correct common mistakes”.

The term scaffolding alludes to a procedure in which instructors display or exhibit how to take care of an issue, and afterward venture back, offering support as required. Analyst and instructional architect Jerome Bruner first utilized the term ‘scaffolding’ in this setting, harking back to the 1960s. The hypothesis is that when understudies are given the help they require while discovering some new information, they stand a superior possibility of utilizing that learning freely. Bruner suggests positive association and three methods of portrayal amid educating: activities, pictures, and dialect.  

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Which explains why an activated complex is a high-energy species? activated complexes form during endothermic reactions. activated complexes require new bonds to be made. activated complexes are stable species with strong covalent bonds. activated complexes cannot be formed in the reverse reaction direction?

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There are two systems in the human body that are responsible for the coordination between the functions of different systems to achieve the unity of the living organism’s body. These two systems are the nervous system and the endocrine system. The action of the nervous system is fast and takes a short time, while the action of the endocrine system is slow and takes a long time.

The functional unit of the nervous system is the nerve cell or the neuron. The neuron consists of a cell body and the axon. The cell body starts with the dendrites that receive the messages or the impulses from other neurons or from different sense organs or receptors. These impulses are then transmitted through the cell body. The cell body contains a nucleus and different organelles which help the nerve cell to perform its functions. The nerve impulse is then transmitted to the axon.

The axon is an extension from the cell body. There are some cells called Schwan cells that secrete a myelin sheath to insulate the axon from the surrounding medium. The insulated axons have more ability to conduct the impulses than non-insulated axons. The axon ends with the terminal arborizations. The terminal arborizations of a nerve cell connect to the dendrites of the next cell or to the afferent organ. The gaps between the dendrites and the terminal arborizations are called the synapses.

The nerve impulse is an electrochemical phenomenon i.e. an electrical phenomenon with a chemical nature. The membrane of the axon acts as a barrier between an outside positively charged medium and an inside negatively charged medium. This makes a potential difference of  -70mV. This state is called the resting potential. When the membrane is subjected to a stimulus, the positive charges enter to inside and the negative charges exit to the outside. The potential difference now becomes +40mV. This state is called the depolarization state. The point of stimulation acts as a new stimulus for the next point and so on. The membrane sooner gains its permeability again and the positive charges return to the outside and the negative charges to inside. This state is called repolarization.

The nerve impulse reaches the synapse. There are some neurotransmitters that are excited by the nerve impulse coming and carry the message across the membrane. Some receptors receive theses neurotransmitters on the dendrites of the next neuron. These receptors act as a stimulus for the new cell.

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Which statement defines reduction potential when considering a pair of half-cell reactions? The half-reaction with the greater SRP has a greater tendency to gain electrons. The half-reaction with the lower SRP has a greater tendency to gain electrons. If each half-reaction has an SRP greater than zero, there will be two reduction reactions. If each half-reaction has an SRP less than zero, there will be two oxidation reactions.

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Answer:

The coefficient of CO₂ is 5.

Explanation:

    Balancing the reaction:

___C₅H₁₂ + ___O₂ → ___CO₂ + ___H₂O

There are 5 C in the left side, so we put 5 on the right side:

___C₅H₁₂ + ___O₂ →  5CO₂ + ___H₂O

There are 12 H in the left side, so we put 6 as the coefficient of H₂O:

___C₅H₁₂ + ___O₂ →  5CO₂ + 6H₂O

Finally, there are 16 O in the right side, so we put 8 as the coefficient of O₂

___C₅H₁₂ + 8O₂ →  5CO₂ + 6H₂O

The coefficient of CO₂ is 5.

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Which substances are responsible for accelerating chemical reactions in cells

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The right answer is Transgenic organisms can produce a desired product that may benefit other organisms.

A transgenic organism contains DNA combining  stably integrated in all its cells. In other words, the organism, be it a plant, an animal or a microorganism, has a new piece of DNA embedded in it. a chromosome in each of its cells. This “new piece” of DNA usually contains a gene from another organism (plant, animal or other) that has been modified to be expressed in the new  organization. A transgenic organism may even possess the DNA of another organism of the same species. The inserted gene can be called the transgene.

Currently, diabetics are treated by injecting insulin from either a healthy human donor or cultures of genetically modified (transgenic) bacteria that secrete the protein.

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Perform an on-line search to discover how a gardener can remedy soil that is overly acidic. support your answer with a sequence of contributing chemical reactions.

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There are two systems in the human body that are responsible for the coordination between the functions of different systems to achieve the unity of the living organism’s body. These two systems are the nervous system and the endocrine system. The action of the nervous system is fast and takes a short time, while the action of the endocrine system is slow and takes a long time.

The functional unit of the nervous system is the nerve cell or the neuron. The neuron consists of a cell body and the axon. The cell body starts with the dendrites that receive the messages or the impulses from other neurons or from different sense organs or receptors. These impulses are then transmitted through the cell body. The cell body contains a nucleus and different organelles which help the nerve cell to perform its functions. The nerve impulse is then transmitted to the axon.

The axon is an extension from the cell body. There are some cells called Schwan cells that secrete a myelin sheath to insulate the axon from the surrounding medium. The insulated axons have more ability to conduct the impulses than non-insulated axons. The axon ends with the terminal arborizations. The terminal arborizations of a nerve cell connect to the dendrites of the next cell or to the afferent organ. The gaps between the dendrites and the terminal arborizations are called the synapses.

The nerve impulse is an electrochemical phenomenon i.e. an electrical phenomenon with a chemical nature. The membrane of the axon acts as a barrier between an outside positively charged medium and an inside negatively charged medium. This makes a potential difference of  -70mV. This state is called the resting potential. When the membrane is subjected to a stimulus, the positive charges enter to inside and the negative charges exit to the outside. The potential difference now becomes +40mV. This state is called the depolarization state. The point of stimulation acts as a new stimulus for the next point and so on. The membrane sooner gains its permeability again and the positive charges return to the outside and the negative charges to inside. This state is called repolarization.

The nerve impulse reaches the synapse. There are some neurotransmitters that are excited by the nerve impulse coming and carry the message across the membrane. Some receptors receive theses neurotransmitters on the dendrites of the next neuron. These receptors act as a stimulus for the new cell.

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Chemical reactions that require oxygen are called _____ while those that do not require oxygen are considered

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The concentration of the H₂SO₄ is 0.20 M. Titration is a technique used to determine the concentration of an unknown solution through its reaction with another substance. An example of the reactions that are used in titration are acid-base reactions. At the equivalence point, the number of moles of the acid are equal to the number of moles of the base. A color change is observed and the resulting solution is neutral.

Further Explanation

The chemical equation for the reaction given is:

H₂SO₄ + 2 LiOH → Li₂SO₄ + 2 H₂O

From the reaction it can be seen that the ratio of the acid and base is 1:2. For every mole of acid neutralized, two moles of the base is used.

To determine the concentration of acid neutralized, remember that at the equivalence point, the number of moles of acid is stoichiometrically equivalent to the moles of base.

Therefore,

moles  of  base  = (0.12 frac{mol}{L} )(0.0836 L)\moles  of   base  = 0.010032 mol

moles  of  acid = 0.010032  mol  LiOH times  frac{1  mol  H_2SO_4}{2  mol  LiOH}\ \boxed {moles  of  acid  = 5.016 times 10^{-3}  mol  H_2SO_4}

To get the concetration of the acid in M, use the the equation below:

Molarity (M) = frac{mole  solute}{volume  solution (in L)}\

To get the molarity of the sulfuric acid:

concentration = frac{5.017 times 10^{-3}  mol  H_2SO_4}{0.025  L}\\boxed {concentration = 0.20064 frac{mol}{L}   or  0.20064  M}

Since the least number of significant figures in the given is 2, then the final answer must be:

boxed {boxed {concentration  of  acid  = 0.20  M  H_2SO_4}}

Learn More

Keywords: titration, acid-base reaction

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How does water regulate body temperature? by dehydration by electrolyte balance by chemical reactions by perspiration

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1. The right answer is A.

High LDL cholesterol, triglycerides, blood pressure  and blood glucose levels are cardiovascular risk factors.

Apart from heredity, sex and age, it is possible to act on many cardiovascular risk factors such as:

*The tobacco

*High blood pressure

*Diabetes

* Excess cholesterol

* Obesity and overweight.

*Physical inactivity.

*The alcohol.

The risk factors do not add up, they potentiate each other, that is, they aggravate each other.

2. The right answer is Body fat percentage.

Measurement of body composition now plays a major role in any fitness assessment.

The percentage of body fat is your fat percentage relative to your body weight. For example, a 70 kg person with a 20% body fat percentage has 14 kg body fat. The ideal body fat varies by sex and also depends on age.

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Which of the following items are true of early nuclear science? Check all that apply. A. The first nuclear reactions were done in the 1880s. B. Some mass of the nucleus was lost in the first nuclear reaction. C. Albert Einstein himself caused the first nuclear reaction. D. The first nucleus split was uranium-235.

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The correct answer is True

Explanation:

In grammar, an antecedent refers to a word or multiple words in the case of compound antecedents that can be replaced by a pronoun such as him, them or her in a sentence as the noun makes reference to the antecedent that is placed before the noun. Additionally, the antecedent and the noun that replace it need to agree on number and genre. For example in the sentence “Maria cannot find her book” the antecedent is “Maria” and the pronoun that replaces it is “her”, which agrees in gender as “Maria” and “her” are both feminine and singular.

This means in the case of using “Male and females” as an antecedent in a sentence, this compound antecedent can be replaced or referenced by the pronoun “them” as this pronoun is plural and can be either feminine or masculine for example the sentence “Male and females are both capable of the same things and therefore equal right should be guaranteed to them” uses the antecedent and pronoun “them” correctly. Therefore, it is true “male and females” could be a compound antecedent referenced by the plural pronoun them.

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Single-replacement reactions A. Consists of two reactants producing two products B. Involve a single product C. Occur when any metal can replace any other metal D. Are restricted to metals

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The answer 

the main rule
A  —– B
A is the reactants  and B the products of a reaction
the number of atome of the elements of A must be equal to the number of atome of the elements of B
in our case
to balance the equation
a0 KI + a1 Pb(NO3)2 → a2 PbI2 + a3 KNO3
 2KI      +   Pb(NO3)2  →     PbI2 +     2KNO3
proof

A (reactants ) ——————– B (products)

 2KI means  2K,   2I             PbI2 :   2I,  2KNO3:  2K ( K and I are balanced) 
 Pb(NO3)2:
1 Pb, 2 NO3                         PbI2 and 2KNO3:  
                                             1Pb and  2 NO3 (Pb and NO3 are balanced)

finally 
 a0= 2,  a1= 1, a2= 1, a3=2                            
            

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Name the compound that is a reactant in all combustion reactions.

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Name the compound that is a reactant in all combustion reactions.

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The Law of Conservation of Matter is a basic principle in studying chemical reactions. True False

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Not true

the 23rd pair of chromosomes are the sex chromosomes, and they determine the sex of an individual.

Girls have two X chromosomes (XX)

Boys have an X and a Y chromosome (XY)

Therefore, the 23rd pair of chromosomes do not have to be homologous, or the same, if the individual is male

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17. Replication, transcription, and translation A. all refer to the synthesis of macromolecules. B. refer to RNA synthesis, DNA synthesis, and protein synthesis, respectively. C. require the synthesis of polysaccharides. D. would be expected to be exergonic reactions. E. all use nucleotides as building blocks. …?

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17. Replication, transcription, and translation A. all refer to the synthesis of macromolecules. B. refer to RNA synthesis, DNA synthesis, and protein synthesis, respectively. C. require the synthesis of polysaccharides. D. would be expected to be exergonic reactions. E. all use nucleotides as building blocks. …?
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An iron fence is left on painted and it reacts with the oxygen in the air form forming rust. the formation of the rest is an oxidation-reduction reaction but it is also an example of a _____ reaction (1 point)8. cooking requires continuous addition of energy to the chemical reactions the are taking place the chemical reaction involved in cooking can be described as______? (1 point)9. measuring how quickly a reactanat disappears in one way to measure the ______of the reaction

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Answer: The correct answer is option(A).

Explanation:

An iron atom emits particles when it is struck by light.This phenomena is called as Photoelectric effect.

Photoelectric effect is defined as when photons (particles of light) falls on the metallic surface, electrons from the surface are ejected out and these ejected out electrons are called photo electrons.

This phenomena was not explained by John Dalton’s model of the atom.

Where as John Dalton’s model of atom explains that matter is made up smallest indivisible particle that is atom, elements combines in fixed proportion with another elements to give compounds, chemical reaction is an arrangement of an atoms.

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Cecil writes the equation for the reaction of hydrogen and oxygen below. H2 + O2 → H2O Why does his teacher ask him to balance the equation by including the correct coefficients? A.to show that most molecules exist in pairs B.to show that most compounds exist in pairs C.to show that atoms are conserved in chemical reactions D,to show that atoms are created in chemical reactions

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Answer: The correct answer is Option D.

Explanation:

Lewis dot structures are the structures which represent the valance electrons of an element forming a compound. The electrons are represented as the dots.

In a compound, the bonded electrons are represented as a bond and lone pair of electrons are represented as dots.

In NH_2^- compound,

Electronic configuration of Nitrogen: 1s^22s^2p^3

Valence electrons in nitrogen = 5

Electronic configuration of hydrogen: 1s^1

Valence electrons in hydrogen = 1

In the given compound, bond pairs are 2 which means number of electrons bonded are 4.

Unbonded electrons left on nitrogen will be 3 and this compound has an extra electron because of the negative charge present on the compound. Hence, total unbonded electrons present on this compound will be 4.

Therefore, the lewis dot structure will be Option D.

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Balance the following reactions CuO+S2

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Balance the following reactions CuO+S2
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Balance the following reactions CuO+S2 ➡️ CuS + SO2

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Balance the following reactions CuO+S2 ➡️ CuS + SO2
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