. Fire can be extinguished by: - a. Lowering temperature below ignition temperature b. Cutting the supply of oxygen c. Removing non-combustible substances from surroundings d. Both a & b

Answer:

The correct option is;

a. Delocalised electrons

Explanation:

The particles that enable electrical conductivity are the delocalised electrons

The metallic structure consists of identically shaped elements having positive ions that have a resultant alignment, surrounded by a vast array of deloclised electrons, which move freely in the metallic structure such that a metallic part usually has a high electrical conductivity.

Therefore, the freely moving delocalised electron in a metal give them the property of good conductors of electricity.

Answer:

50%

Explanation:

Expected measurement required = 10g

Actual measurement observed = 15g

The percentage error is given as proportion the difference between the actual and expected measurement or values and the expected value value expressed as a percentage.

[(Actual - Expected) / Expected] × 100%

[(15 - 10) / 10)] × 100%

(5 / 10) × 100%

0.5 × 100%

50%

Therefore, the percentage error in the measurement is 50%

Answer:

0.35 g.

Explanation:

We'll begin by calculating the number of mole of Fe(NO3)3 in 35 mL of 0.250 M Fe(NO3)3 solution.

This is illustrated below:

Molarity of Fe(NO3)3 = 0.250 M

Volume = 35 mL = 35/1000 = 0.035 L

Mole of Fe(NO3)3 =?

Molarity = mole /Volume

0.250 = mole of Fe(NO3)3 / 0.035

Cross multiply

Mole of Fe(NO3)3 = 0.25 x 0.035

Mole of Fe(NO3)3 = 8.75×10¯³ mole

Next, we shall determine the number of mole of KOH in 55 mL of 0.180 M

KOH solution. This is illustrated below:

Molarity of KOH = 0.180 M

Volume = 55 mL = 55/1000 = 0.055 L

Mole of KOH =.?

Molarity = mole /Volume

0.180 = mole of KOH /0.055

Cross multiply

Mole of KOH = 0.180 x 0.055

Mole of KOH = 9.9×10¯³ mole.

Next, we shall write the balanced equation for the reaction. This is given below:

3KOH + Fe(NO3)3 —> Fe(OH)3 + 3KNO3

From the balanced equation above,

3 moles of KOH reacted with 1 mole of Fe(NO3)3 to produce 1 mole of Fe(OH)3.

Next, we shall determine the limiting reactant. This can be obtained as follow:

From the balanced equation above,

3 moles of KOH reacted with 1 mole of Fe(NO3)3.

Therefore, 9.9×10¯³ mole of KOH will react with = (9.9×10¯³ x 1)/3 = 3.3×10¯³ mole of Fe(NO3)3.

From the above illustration, we can see that only 3.3×10¯³ mole out of 8.75×10¯³ mole of Fe(NO3)3 given is needed to react completely with 9.9×10¯³ mole of KOH.

Therefore, KOH is the limiting reactant and Fe(NO3)3 is the excess reactant.

Next, we shall determine the number of mole of Fe(OH)3 produced from the reaction.

In this case, we shall use the limiting reactant because it will give the maximum yield of Fe(OH)3 as all of it is consumed in the reaction.

The limiting reactant is KOH and the mole of Fe(OH)3 produce can be obtained as follow:

From the balanced equation above,

3 moles of KOH reacted to produce 1 mole of Fe(OH)3.

Therefore, 9.9×10¯³ mole of KOH will react to produce = (9.9×10¯³ x 1)/3 = 3.3×10¯³ mole of Fe(OH)3.

Finally, we shall convert 3.3×10¯³ mole of Fe(OH)3 to grams. This can be obtained as follow:

Molar mass of Fe(OH)3 = 56 + 3(16 + 1) = 56 + 3(17) = 107 g/mol

Mole of Fe(OH)3 = 3.3×10¯³ mole

Mass of Fe(OH)3 =?

Mole = mass /Molar mass

3.3×10¯³ = Mass of Fe(OH)3 / 107

Cross multiply

Mass of Fe(OH)3 = 3.3×10¯³ x 107

Mass of Fe(OH)3 = 0.3531 ≈ 0.35 g.

Therefore, 0.35 g of Fe(OH)3 was produced from the reaction.

Answer:

Inverse proportion occurs when one value increases and the other decreases. For example, more workers on a job would reduce the time to complete the task. They are inversely proportional.

Answer:

A

Explanation:

Answer:

The volume of hydrogen gas produced at s.t.p. is 9.419 dm³

Explanation:

The balanced chemical equation for the reaction is given as follows;

Zn + 2HCl → ZnCl₂ + H₂

Therefore, we have;

One mole of Zn reacts with 2 moles of HCl to produce one mole of ZnCl₂ and one mole of H₂

Number of moles of Zn present = 25/65 = 5/13 = 0.385 moles

Therefore, number of moles of H₂ produced = 0.385 moles

The volume of hydrogen gas produced is given by the relation

PV = nRT, we have;

R = 8.3145 J/(mol·K)

V = nRT/P = 0.385 ×8.3145 ×298.15/(101325)= 0.009419 m³ = 9.419 dm³

The volume of hydrogen gas produced at s.t.p. = 9.419 dm³.

Answer:

The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time, and is constant if and only if all processes are reversible.

Explanation:

Isolated systems spontaneously evolve towards thermodynamic equilibrium, the state with maximum entropy. hope this helps you :)

The second law of thermodynamics say about entropy The entropy in a system and its surroundings tends to increase.

According to the second law of thermodynamics, Entropy of the universe keeps on increasing overtime. When the entropy decreases and enthalpy increases the free energy change,  ΔG, is positive and not spontaneous, and it does not matter what the temperature of the system is. Temperature comes into play when the entropy and enthalpy both increase or both decrease. The reaction is not spontaneous when both entropy and enthalpy are positive and at low temperatures, and the reaction is spontaneous when both entropy and enthalpy are positive and at high temperatures. The reactions are spontaneous when the entropy and enthalpy are negative at low temperatures, and the reaction is not spontaneous when the entropy and enthalpy are negative at high temperatures.

Therefore, The second law of thermodynamics say about entropy The entropy in a system and its surroundings tends to increase.

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Answer:

FADH2 has a lower (less negative) redox potential than NADH does

Explanation:

Flavin Adenine Dinucleotide (FAD) and Nicotinamide Adenine Dinucleotide (NAD) are redox cofactors that play important functions for mitochondrial activity and cellular redox balance. Both coenzymes exist in two forms: an oxidized and a reduced, which are abbreviated as NAD/FAD and NADH/FADH2, respectively. These reduced forms (NADH and FADH2) are produced in the Krebs cycle during respiration. FADH2 has lower redox potential than NADH because FADH2 is only capable of activating 2 proton pumps, while NADH can activate 3 proton pumps during the electron transport chain, thereby FADH2 generates a minor number of ATP molecules than NADH.

Answer: D. False, it should read, "A theory and a law are already both supported by evidence and are equal, but they have different functions."

Explanation:

A  "Theory" and  a'' Law" in scientific method are already both supported by evidence but they have different function,

The function of  " Theory" in scientific method is to give an explanation to the observations and findings gathered during the process. It can be modified, improved or even rejected as more information is being gathered.

While a '' Law '' tends to describe an observed event in nature that is true whenever it is put to test. It does not explain why the occurence or event is true.

Answer:

Electron gain enthalpy becomes more and more negative from left to right in a period. As we move across a period from left to right the atomic size decreases and the nuclear charge increases

Answer: Variation in electron gain enthalpy in the period : in the modern periodic table, on moving from left to right across a period the atomic size of elements decreases and the effective nuclear charge increases.

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Explanation:

Answer:

The body stores lipids ingested as fat and uses this energy when needed-chemical energy

A person's hat falls off and lands on the ground- gravitational energy

A wave of water pushes a surfer to shore- mechanical energy

A burner on a stove heats up a tea kettle- thermal energy

A power plant splits atoms to generate power for a city- nuclear energy

A nerve sends an impulse to another nerve- electrical energy

A plant absorbs the Sun's rays to start the process of photosynthesis- radiant energy

Explanation:

Gravitational energy is energy stored by an object as a consequence of its height.

Mechanical energy is the energy that is possessed by an object due to its motion or due to its position.

Chemical energy refers to energy stored in chemical bonds in a substance.

Thermal energy is a form of energy that exists due to temperature difference between two bodies.

Nuclear energy refers to energy stored in the nucleus of an atom.

Electrical energy is a form of energy resulting from the flow of electric charge.

Radiant energy refers to energy that moves through vacuum without passing through a material medium.

Answer:

true

Explanation:

The standard laboratory rule is to always add acids or bases to solvent and not the other way round.

The dissolution of concentrated acids/bases in solvents (water) generates heat energy. Thus, if the solvent is added to them, a layer of hot weak acid or base will be formed and this will boil and spray around, causing an explosion.

On the other hand, if acid/base is added to solvents, they flow into the solvents and get diluted immediately without any boiling taking place. Hence, it is safe to add acid/base to solvents and not the other way round.

Answer:

C. the same amount of energy as

Explanation:

Firstly, a chemical reaction can either absorb energy from its surroundings to occur or release energy into its surroundings as a product. The former and latter descriptions are called ENDOTHERMIC and EXOTHERMIC reactions respectively. An exothermic reaction is that which transfers energy, in form of heat, to its surroundings while an Endothermic reaction is that which absorbs energy (heat) from its surroundings.

However, a reversible reaction is that reaction in which the formation of products from reactants and reformation of the reactants from products occur simultaneously. Hence, the products of a reversible reaction can become the reactants and move in the opposite direction. For example:

Reversible reaction: A + B ⇆ C + D means;

A + B → C + D and;

C + D → A + B

In a case whereby the opposite reactions consist of an endothermic and exothermic reactions, the endothermic reaction absorbs the same amount of energy as the exothermic reaction releases.

According to the law of conservation of energy, no energy is lost during a reversible reaction. Hence, in order to achieve an equilibrium, the amount of energy absorbed by the endothermic reaction is the same as the amount of energy released in the opposite exothermic reaction.

This question is incomplete, here´s the complete question.  

How does the percentage of monounsaturated and polyunsaturated fatty acids in olive oil compare to that of canola oil? Match the words in the left column to the appropriate blanks in the sentences on the right.

Olive oil has about ____ monounsaturated fats, while canola oil has about ___.

Olive oil has about ___ polyunsaturated fats, while canola oil has about ___.

6%

10%

30%

84%

5%

65%

Answer:

Olive oil has about 84% monounsaturated fats, while canola oil has about 65%.

Olive oil has about 5% polyunsaturated fats, while canola oil has about 30%.

Explanation:

Olive and canola oil are the major sources of monounsaturated fatty acids. Although vegetable oils usually have high concentrations of polyunsaturated fatty acids and less monounsaturated fats, olive and canola oils have comparatively less polyunsaturated fatty acids, and more monounsaturated fatty acids.

Answer:

C is gaining 2 electrons

Explanation:

O has a 2- charge so for CO to pick up another O atom would add 2 more electrons.

Answer:

C gains 2 electrons

Explanation:

In the redox reaction, CO is changed into CO2 which means there is an additional oxygen. Oxygen loses 2 of its electrons in order to neutralize. So, C must be gaining 2 electrons in order to make the bond.

Answer:

ionic

Explanation:

In NH4Cl molecule, ionic bond is formed between NH4+ and Cl– ions, 3 covalent bonds are formed between N and three H atoms and one coordinate bond is formed between N and 1 H atom.

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Answer:

[tex]\boxed{\sf c. \ ionic}[/tex]

Explanation:

NH₄Cl is formed by an ionic bond between NH₄⁺ and Cl⁻ ions.

NH₄Cl (solid) ⇒ NH4⁺ (aqueous) + Cl⁻ (aqueous)

Answer:

Electrons orbit the nucleus.

Answer:

electrons

Explanation:Atoms are made up of protons and neutrons located within the nucleus, with electrons in orbitals surrounding the nucleus.

Answer: B

Explanation: Apex

An electron configuration be used to predict relative atomic size because the larger the highest energy level number, the larger the atomic

radius.

The electron configuration of an element shows the arrangement of electrons in atoms of that element.

As more sublevels are added, repulsion between electrons occupying shells increases causing a greater shielding and consequent increase in the size of the atom.

Hence, the larger the highest energy level number, the larger the atomic

radius.

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Answer:

Ni(ClO₄)₂(aq) ⇒ Ni²⁺(aq) + 2 ClO₄⁻(aq)

8 mol ClO₄⁻

Explanation:

Let's consider the dissolution equation for nickel(II) perchlorate dissolving in water.

Ni(ClO₄)₂(aq) ⇒ Ni²⁺(aq) + 2 ClO₄⁻(aq)

The molar ratio of Ni(ClO₄)₂ to ClO₄⁻ is 1:2. If 4 moles of Ni(ClO₄)₂ are dissolved, the moles of ClO₄⁻ formed are:

4 mol Ni(ClO₄)₂ × (2 mol ClO₄⁻/ 1 mol Ni(ClO₄)₂) = 8 mol ClO₄⁻

Answer:

0.8833 mole of C3H8

Explanation:

Given:

Mass of C₃H₈ (Propane) = 38.95 gram

Computation:

Molar mass of C = 12.01

Molar mass of H = 1.008

Molar mass of C₃H₈ (Propane) = 3(12.01) + 8(1.008)

Molar mass of C₃H₈ (Propane) = 36.03 + 8.064

Molar mass of C₃H₈ (Propane) = 44.094

Number of mol in 38.95 gram Propane = Mass / Molar mass

Number of mol in 38.95 gram Propane = 38.95 / 44.094

Number of mol in 38.95 gram Propane = 0.88334

Answer:

Use the Periodic Table to find molar masses.

Propane (C3H8), a common fuel, reacts with oxygen to form carbon dioxide and water according to the equation below:

C3H8 + 5O2 → 3CO2 + 4H2O

If a propane heater burns 38.95 g C3H8, it consumes

38.95 mol C3H8.

0.8830 mol C3H8.

1 mol C3H8.

44.10 mol C3H8.

Part 2

How many moles of oxygen are required to produce 37.15 g CO2?

37.15 g CO2 = 1.407 mol O2

Part 3

What mass of propane is necessary to react with the amount of oxygen calculated in the previous question?

12.41   g C3H8    

Answer:

The volume at 0.860 atm and 15°C will be 56.638 L

Explanation:

Gay Lussac's law explains the variation in the pressure of a gas by modifying its temperature, keeping the volume constant: it determines that pressure and temperature are directly proportional quantities. In other words, Gay-Lussac's law states that when a gas undergoes a constant volume transformation, the ratio of the pressure exerted by the temperature of the gas remains constant:

[tex]\frac{P}{T}=k[/tex]

On the other hand, Boyle's law determines that the pressure exerted by a gas is inversely proportional to its volume at constant temperature. This is expressed mathematically as:

P*V=k

Finally, Charles's law says that at constant pressure, the volume of an ideal gas is directly proportional to its absolute temperature and is expressed mathematically as:

[tex]\frac{V}{T}=k[/tex]

Combined law equation is the combination of three gas laws called Boyle's, Charles's and Gay-Lussac's law:

[tex]\frac{P*V}{T}=k[/tex]

When you want to study two different states, an initial one and a final one of a gas, you use:

[tex]\frac{P1*V1}{T1}=\frac{P2*V2}{T2}[/tex]

In this case:

Replacing:

[tex]\frac{1.05 atm*48 L}{298 K}=\frac{0.86atm*V2}{288 K}[/tex]

and solving:

[tex]V2=\frac{288 K}{0.86 atm} *\frac{1.05 atm*48 L}{298 K}[/tex]

you get:

V2= 56.638 L

The volume at 0.860 atm and 15°C will be 56.638 L

Answer:

The answer is the same as .

Explanation:

There are 3 atoms in NaOH, 1 sodium, 1 oxygen and 1 hydrogen.

There are 3 atoms in H2O, 2 hydrogen and 1 oxygen.

Answer:

88

Explanation:

The ion has a charge of 2+, therefore the number of neutrons it possess is 86+2

which equals 88

The element X having a mass number of 230 and has 86 electrons is radium and has  142 neutrons.

An atom is composed basically of electrons, protons and neutrons. In a neutral atom, the number of protons and electrons are equal. The number of neutrons is the difference between the mass number and the number of protons (atomic number).

Since we know that the ion of the element X has 86 electrons and the compound formed is XBr2, it then means that neutral X has 88 electrons.

The number of electrons in the neutral atom is the same as the number of protons or atomic number. An element can be identified by its atomic number. The element having atomic number 88 is radium.

The number of neutrons is obtained as;

Mass number - atomic number

230 - 88 = 142 neutrons

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Answer:

It is non - polar

Explanation:

Oil is a non-polar chemical substance that is a viscous liquid at ambient temperatures and is both hydrophobic (does not mix with water).

Water and oil do not mix. They are said to be immiscible. This is because water is a polar molecule.

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Answer:

using a more concentrated potassium hydroxide

Explanation:

The option that would likely increase the rate of reaction would be to use a more concentrated potassium hydroxide.

The concentration of reactants is one of the factors that affect the rate of reaction. The more the concentration of the reactants, the faster the rate of reaction.

Granted that there are enough of the other reactants, increasing the concentration of one of the reactants will lead to an increased rate of reaction.

Hence, using a more concentrated potassium hydroxide which happens to be one of the reactants would likely increase the rate of reaction.

Answer:

using a more concentrated potassium hydroxide

Explanation:

Answer:

i) b

ii) c

Explanation:

Please see attached picture for full solution.

Answer:

composition of soda-lime glass is 73% SiO2 – 15% Na2O − 7% CaO − 4% MgO − 1% Al2O3 [129,132,133].

The Soda glass formula is SiO2, Na2O, CaO, Al2O3, K2O, SO3, MgO, Fe2O3, TiO2

Soda glass is a chemical compound that stands out for being the most widely used material to make windows, bottles, glasses, among others.

This compound is characterized by being chemically stable, reasonably hard, and extremely versatile because it can be recycled since it can be melted to make new products.

Its chemical formula is made up of other compounds such as:

Additionally, the compounds found in the highest proportion in glass are SiO2 (74 atoms) and Na2O (13 atoms).

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Answer: The new relative charges between two atoms are +1 and -1 for cation and anion respectively.

Explanation:

When an atom accepts an electron, negative charge is created on atom and is called as anion.

When atom loses an electron, positive charge is created on atom and is called as cation.

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

Thus when one electron is lost by an atom it forms one positive charge and when one electron is gained by an atom it forms one negative charge.

Foe example: sodium atom loses its one valance electron and form cation [tex]Na^+[/tex]. Chlorine atom gain one electron and form anion [tex]Cl^-[/tex].  they both combine to form sodium chloride through ionic bond.

Answer:

The Conservation area is the pay way to the special architectural and historic interest  these are special character.

Explanation:

Conservation area is the features of building and use that historical development to contribute to its special character material and style.

Explanation:

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