Answer the following questions:
1. Define a compound. State three points of evidence to show that sodium chloride is a compound.
2. When Iron powder and Sulphur powder were mixed together and heated strongly, a substance A was formed. When did. Hydrochloric acid was added to substance A, the gas B was evolved.
a) What is A and what type of substance is it?
b) Name the gas B. State one characteristic property of gas B.
c)Is the reaction of Iron and Sulphur powder a chemical change or a physical change.
Answer the question according to the class 9th student.

Answer:

It has been balanced by using the half-reaction method.

Explanation:

I- and IO3- gives I2

We divide the reaction into two half-reactions

(2 I- >> I2 + 2e-) x5 ( oxidation  : I goes from -1 to 0 )

2 IO3- + 12H+ + 10e- >> I2 + 6H2O ( reduction : I goes from +5 to 0 )

10 I- >> 5I2 + 10e-

2IO3- + 12H+ + 10e- >> I2 + 6H2O

-----------------------------------------------------

10 I- + 2IO3- + 12H+ >> 6I2 + 6H2O

To get the smallest numbers we divide by 2 :

5 I- + IO3- + 6H+ >> 3I2 + 3H2O

It has been balanced by using the half-reaction method. Hence, option B is correct.

A chemical reaction that takes place between an oxidizing substance and a reducing substance.

We divide the reaction into two half-reactions

[tex](2 I^-[/tex] → [tex]I_2 + 2e^-)[/tex] x 5 ( oxidation  : I goes from -1 to 0 )

[tex]2 IO^{3-} + 12H^+ + 10e^-[/tex] → [tex]I_2 + 6H_2O[/tex] ( reduction : I goes from +5 to 0 )

[tex]10 I^-[/tex] →[tex]5I_2 + 10e^-[/tex]

[tex]2IO^{3-} + 12H^+ + 10e^-[/tex] → [tex]I_2 + 6H_2O[/tex]

[tex]10 I^- + 2IO^{3-} + 12H^{+}[/tex]→ [tex]6I_2 + 6H_2O[/tex]

To get the smallest numbers we divide by 2 :

[tex]5 I^- + IO^{3-} + 6H^+[/tex] → [tex]3I_2 + 3H_2O[/tex]

Hence, option B is correct.

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Answer:

Chemical Changes are also called Chemical Reactions. Chemical reactions involve combining different substances. The chemical reaction produces a new substance with new and different physical and chemical properties. Matter is never destroyed or created in chemical reactions.

Explanation:

Answer:

A

Explanation:

civil deals with desighning, construction work of natural or physical environment and a fits guess

Answer:

oppositely charged ions in a chemical compound

Explanation:

Answer:

Between ions

Explanation:

The question is incomplete, the complete question is;

A student investigated some properties of lead and recorded the findings in the table below. Property Observation Color Dull gray Density 11.3 g/cm3 Volume of sample 3 cm3 Melting point 327°C Reaction with air Lead oxide forms on the surface Electrical conductivity Conducts some electricity Which statement is true with respect to the investigation?

A. The student investigated only the physical properties of lead.  

B. The student investigated only the chemical properties of lead.  

C. The student investigated more physical properties than chemical properties of lead.  

D. The student investigated more chemical properties than physical properties of lead.

Answer:

The student investigated more physical properties than chemical properties of lead.

Explanation:

If we look at the things mentioned in the question as regards the approach of the student towards the study of lead, we will discover that he/studied;

Colour, density, volume, melting point and electrical conductivity which are all physical properties. Physical properties of a substance does not involve chemical reactions of the substance under study.

The only chemical property studied by the student is its formation of an oxide- lead oxide with air as follows;

2Pb(s) + O₂(g) → 2PbO(s)

Thus we can safely conclude that; the student investigated more physical properties than chemical properties of lead.

Answer:

c

Explanation:

edge 2021 :)

Answer:

A- Ca

B- Ca(OH)2

C-CaCO3

D- CaO

Explanation:

Element A is calcium. Calcium reacts with water to form calcium hydroxide (compound B) as follows; Ca(s) + 2H2O(l) ----> Ca(OH)2(s) + H2(g).

When exposed to air, calcium hydroxide (compound B) forms calcium trioxocarbonate IV (CaCO3) which is compound C as follows;

Ca(OH)2(s) + CO2(g) -----> CaCO3(s) + H2O(l)

On heating compound C, the oxide, CaO (D) is formed as follows;

CaCO3(s) ------> CaO(s) + CO2(g)

This oxide reacts with water to yield B again as follows;

CaO(s) + H2O(l) ----> Ca(OH)2(s)

Explanation:

pH is used to measure the concentration of H+ ions ([H+]) and therefore, whether a substance is acidic or basic (alkaline). Solutions with a pH of less than seven are acidic, while those with a pH greater than seven are basic (alkaline).

Answer:

greater than 7

Explanation:

A base is any solution with a pH greater than 7. A pH of 7 is considered neutral. For example, the pH of water. An acid is any solution with a pH less than 7.

Hope that helps.

Answer:

The chemical bond between 2 molecules is called an intermolecular force.

Answer:

Chemical Bond:

Attraction between two atoms results in the formation of a bond which is called a chemical bond.

Inter molecular Forces:

Attractive Force that in between 2 molecules is called Inter molecular Forces. (Inter : Between)

Answer:

The statement that describes an electron is "It has a negative charge and is located in orbitals around the nucleus." Electrons are the smallest of the three particles that make up atoms

Explanation:

Electrons are found in shells or orbitals that surround the nucleus of an atom

Electrons are the sub-atomic particles that carry a negative charge over them. In the atom, the electrons are found in the orbitals or the shells around the nucleus. Thus, option D is correct.

Electrons are the smallest sub-atomic particle that has been known to carry a negative charge and are found in the orbitals of the atom. The charge carried by an electron is 1.602 x 10⁻¹⁹ coulomb and is small than the proton and neutron.

They revolve around the nucleus in their orbits and exhibit the properties of waves and matter. The number of electrons and protons are the same in a neutral atom which makes the atomic number.

Therefore, the electrons have been known to carry a negative charge that revolves in orbit around the nucleus.

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Your question is incomplete, but most probably your full question was, Which statement describes an electron?

Answer:

A.

Explanation:

Higher temperature - more kinetic energy - more space between particles - higher volume.

It has a double C=C bond so that means it's unsaturated, but it can also be a cyclic compound with only simple C-C bonds

Alkene

I did the test

Answer:

See explanation

Explanation:

Charles law gives the relationship between volume and temperature of a gas. Charles law States that, the volume of a given mass of gas is directly proportional to its temperature at constant pressure.

Theoretically, it is assumed that when the absolute zero temperature has been achieved, the volume of any ideal gas will be found to be equal to zero. If the volume of the gas is zero, it now implies that all molecular motion will be stopped. This does not happen in real gases as all gases are found to condense to solids or liquids when this temperature is exceeded.

When volume is plotted against temperature, volume of the gas approaches zero at t = −273.15 °C, which is the x-intercept of the Charles law graph. Below this temperature, we can only get negative values of volume which does not exist hence, −273.15 °C is the lowest attainable temperature also known as the absolute zero.

Answer:

NO! It would be in violation of the workplace regulation regarding oxygen.

Explanation:

Bulk oxygen systems convey liquified oxygen which is of geat use and importance in institutions like a nuirsing home.

Liquified oxygen is gaseos oxygen that has been condensed under high presures into liquid form. It is transported via a complex system of vaporizers, storage tanks and pipes around the facility it is needed. Liquified oxygen is oxygen- rich.

Asphalt is a petroleum derivative that is often used to in coating surfaces and tarring roads.

Its primry constituent is Carbon with minor constitunets like sulphur, nirogen, oxygen. As a petrolem derivative, it is very combustible.

In the event of an oxygen leak on an asphalt surtface, oxygen acting as an oxidizing agent can combine with asphalt in the presence of air, to cause a large fire.

Hence, asphalt surfacing in areas of oxygen leaks, would not be in compliance with the workplace regulation as it has the potential of causing a fire in the nursing home.    

Answer:

The correct options are;

C. Divergent plate boundary

D. Normal faults

Explanation:

Tensile stress tends to pull objects part by acting axially upon the object to pull the object on a cross section perpendicular to the objects cross-section

The most common stress in convergent plate boundaries is compression stress

The most common stress in divergent plate boundaries is tensile stress

In the presence of tensile stress, normal faults results in the raising of mountains due to their enormous forces

Therefore, the features of Earth's crust involving tension are divergent plate boundary and normal faults.

Answer:c and d

Explanation:

Answer:

The acid solution is a concentrated solution.

Explanation:

Acetic acid is a weak acid, because it ionizes partially in water as shown below:

CH3COOH + H2O —> H3O+ + CH3COO-

A solution containing a larger quantity of acetic acid is termed concentrated solution.

This is so because a concentrated solution is a solution that contains more of the solute than the solvent.

A solute is the substance which dissolves in the solvent.

A solvent is the substance which dissolves a solute.

In this case, acetic acid is the solute and water is the solvent.

Solution is simply the combination of solute and solvent

Solution => Solute + Solvent

More solute + Less solvent => Concentrated solution

Therefore, a solution containing a higher quantity of acetic acid ( i.e the solute) in water (i.e the solvent) is called a concentrated solution.

Answer:

NH4Cl

Explanation:

i just did the test

Answer:

NH4Cl

Explanation:

Edg 2020

[tex]7.408 \;X 10 ^ {-3} m^{-2} s^{-1}[/tex]  is rate of a reaction when k = 0.2, [A] = 3 M, [B] = 3 M, m = 1, n = 2 .

The rate at which the concentration of reactant or product participating in a chemical reaction alters is called the rate of reaction.

Rate of reaction = [tex]\frac{change \;in \;concentration}{time}[/tex] =  (mol/litre)/time.

m= 1 and n = 2

[tex]rate = K [A] [B]^2[/tex]

[tex]0.2 = K X 3 X 3 ^2[/tex]

K =   [tex]\frac{0.2 }{27 }[/tex]

K =   [tex]7.408 \;X 10 ^ {-3} m^{-2} s^{-1}[/tex]

Hence, [tex]7.408 \;X 10 ^ {-3} m^{-2} s^{-1}[/tex]  is rate of a reaction when k = 0.2, [A] = 3 M, [B] = 3 M, m = 1, n = 2 .

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Answer: 7.4 10-3

Explanation:

7.4 10-3 this is right ong

Answer:

Explanation:0.493 M NaOH means 0.493 mol NaOH/L

mols

mols = ------ x L

L

mols = M x V

In a titration procedure, 40.57 mL of 0.493 M NaOH solution was used. How many mols NaOH did this volume of NaOH solution contain?

mols = M x V

0.493 mols NaOH

mols = ----------------------- x 0.04057 L

L

mols = 0.0200 mols NaOH

Answer:

Fossil fuels are formed when living organisms die, and are buried under a tick layer of earth materials over a long time, usually over million s of years. Fossil fuels are formed under intense heat and pressure on the dead organisms due to the earth layer that has accumulated on the organisms over the years. The type of fossil fuels formed in a particular region depends on the type of organism that has lived in that region over the years, and the climate of the region. Regions with lush, swamp forests with many trees have enough  organic material to make coal over the years. The United states however still depend on the importation of other fossil fuel that are in minimal quantity in the country. Most regions have coal, because they once had forests and animals on them but countries like the United States and some other countries have them in abundance, because these regions had a huge amount of lush, swamp forests with many trees. Japan lacks significant domestic reserves of fossil fuel, except coal, and must import substantial amounts of crude oil, natural gas, and other energy resources, because of its climate and the fact that it is an island nation.

Fossil fuels are distributed unevenly because their formation requires precise conditions that aren’t found everywhere. For fossil fuels to form, they need to be subjected to anoxic (lacking oxygen) conditions that allow for great pressure, such as those found beneath the ocean floor.nation:

Explanation:

Cyclopropane is a cycloalkane conposed of three carbon atoms to form a ring. It has a rols as an inhalation anaesthetic. It is a cycloalkane and a member of cyclopropanes.

Answer:

Alkane

Explanation:

Answer:

balanced equation:

2Ca(NO3)2 (aq)-----> 2CaO (s) + 4NO2 (g) + O2 (g)

So heating 2 moles of Ca(NO3)2 gives 2 moles of CaO, 4 moles of NO2 and 1 mole of O2. This is a heat decomposition reaction. It gives a white precipitate (CaO), and brown pungent gas (NO2).

Answer:

The balanced equation of the reaction is below.

Explanation:

2Ca(NO3)2 -----> 2CaO + 4NO2 + O2.

Answer:

[tex]\boxed{\mathrm{Iodine}}[/tex]

Explanation:

Halogens are elements in group 17 or 7 in the periodic table.

Iodine is a halogen.

Therefore, iodine, an Halogen

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Answer:

C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O

Explanation:

Let's start by counting how many molecules we have on each side.

Reactants

C - 5

H - 12

O - 2

Products

C - 1

O - 3

H - 2

We have to balance both sides. Since we have 5 carbon atoms on the reactants side and 1 carbon atom on the products side, we'll start with that. Write 5 as the coefficient for CO₂ to balance the carbons.

C₅H₁₂ + O₂ → 5CO₂ + H₂O

Now that the carbons are balanced, let's look at the hydrogens. There's 12 on the reactants side and 2 on the products side. To balance the hydrogens, we have to write 6 as the coefficient for H₂O.

C₅H₁₂ + O₂ → 5CO₂ + 6H₂O

Now the hydrogens are balanced. All that's left to do is balance the oxygens. Let's start by counting how many atoms we have on each side.

Reactants

C - 5

H - 12

O - 2

Products

C - 5

H - 12

O - 16

So, to balance the number of atoms on both sides, write 8 as the coefficient for O₂.

C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O

Lastly, let's check to make sure everything is balanced.

Reactants

C - 5

H - 12

O - 16

Products

C - 5

O - 16

H - 12

Both sides are balanced. Therefore, the balanced chemical equation is: C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O.

Hope that helps.

Answer:

[tex]\boxed{C_{5}H_{12} + 8O_{2} -->5CO_{2} + 6H_{2}O}[/tex]

Explanation:

Part 1: Count the number of atoms on each side per element

To start, count the number of atoms per element on both sides of the equation.

Left Side

C - 5 atoms

H - 12 atoms

O - 2 atoms

Right Side

C - 1 atom

H - 2 atoms

O - 3 atoms

Part 2: Balance carbon atoms

Now, with this information, you can begin finding out how to properly balance both sides of the equation.

You need 5 carbon atoms on the left, so place a coefficient of 5 in front of the [tex]CO_{2}[/tex] product. This will balance the carbons. Do not place a coefficient in front of the [tex]C_{5}H_{12}[/tex] reactant - none are necessary!

Then, you can update your counts for your atoms.

Left Side

C - 5 atoms

H - 12 atoms

O - 2 atoms

Right Side

C - 5 atoms

H - 2 atoms

O - 11 atoms

The updated equation will look like this:

[tex]\boxed{C_{5}H_{12}+O_{2} --> 5CO_{2} + H_{2}O}[/tex]

Part 3: Balance hydrogen atoms

Now, balance the hydrogen atoms. Place a coefficient of 6 in front of the [tex]H_{2}O[/tex] product. This will balance the hydrogen atoms.

Once again, update the atom counts:

Left Side

C - 5 atoms

H - 12 atoms

O - 2 atoms

Right Side

C - 5 atoms

H - 12 atoms

O - 16 atoms

The updated equation will look like this:

[tex]\boxed{C_{5}H_{12} +O_{2}--> 5CO_{2} +6H_{2}O}[/tex]

Part 4: Balance oxygen atoms

To fully balance the equation, place a coefficient of 8 in front of the [tex]O_{2}[/tex] reactant. This will equalize the amount of oxygen atoms on both sides of the equation.

The updated equation will look like this:

[tex]\boxed{C_{5}H_{12} + 8O_{2} --> 5CO_{2} + 6H_{2}O}[/tex]

Part 5: Check the equation and atom counts

Now, update the atom counts one last time to make sure they are equal.

Left Side

C - 5 atoms

H - 12 atoms

O - 16 atoms

Right Side

C - 5 atoms

H - 12 atoms

O - 6 atoms

They are equal, so you may proceed.

Part 6: Check if reductions are necessary

If the equations coefficients can all be divided by a common divisor (i.e., 3), follow up with that step. However, any equation that has a reactant or product without a coefficient, skip this step entirely.

This equation falls into that category, so you may proceed past it.

Your final equation will look like this: [tex]\boxed{C_{5}H_{12} + 8O_{2} -->5CO_{2} + 6H_{2}O}[/tex]

Answer:

Transition metals (Group C) have different numbers of valence electrons compared to the other groups mentioned. Therefore option C is correct.

Transition metals (Group 3-12) have varying numbers of valence electrons. This is because their valence electrons are located in more than one energy level or subshell.

The number of valence electrons for transition metals can range from 1 to 12, depending on the specific element within the group. The varying numbers of valence electrons in transition metals contribute to their diverse chemical properties and ability to form multiple oxidation states.

Therefore, transition metals (Group C) have different numbers of valence electrons compared to the other groups mentioned.

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Answer:

(b)

Explanation:

The 3s^2, 3p^6  orbitals form  -3 charge.

This is the element phosphorous and an example of a -3 ion is in aluminium phosphide, AlP3.

The electronic configuration which represents the element forming a simple ion having with a charge of -3 is; 1s², 2s², 2p⁶, 3s², 3p³. Option B is correct.

In this electronic configuration, the element has a total of 16 electrons. To form a simple ion with a charge of -3, the element needs to gain three electrons. This is achieved by adding three extra electrons to the existing configuration.

When the element gains three electrons, the electron configuration becomes:

1s², 2s², 2p⁶, 3s², 3p⁶

This configuration represents the stable octet configuration, where the element has a complete outer shell with eight electrons. Since the charge is -3, it means the element has gained three extra electrons to achieve a stable configuration.

Therefore, the correct electronic configuration representing the element that forms a simple ion with a charge of -3 is 1s², 2s², 2p⁶, 3s², 3p³

Hence, B. is the correct option.

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Answer: Love is when you feel like you can touch the sky when your around that person, when your at your best self or that person and when you put their needs before yours because your needs just don't matter. When you feel like you can't stop thinking about that person or you can stop smiling when you think of them. Its when you feel this warm, safe feeling when your around them. And if you really love them then my answer should be true for you.

Explanation:

because iv'e felt and have been in love before....

Answer:

Love is an intense, deep affection for another person. Love also means to feel this intense affection for someone. Love can also refer to a strong like for something or to like something a lot. Love has many other senses both as a verb and a noun

Explanation:

astronomers have discover that in general the future of a Galaxy is, the more redshift light is this mean that the further away the Galaxy are the faster they are moving this is similar to explosion where the bits moving fastest travel for furthest on the explosion redshift data provides evidence that the universe including space itself is expanding .

Answer:

A large point of evidence in this would be the rate of increase in how fast the polar ice caps are melting and the ocean is rising as a result. As the climate is getting warmer so are the oceans and this is causing the ice caps which are in the ocean.

Explanation:

The Option C is correct precipitation is concentrated in the season

Hope it help

Answer:

C) precipitation is concentrated in one season

Explanation:

edge 2020

Answer:

Here's what I get from one source.

Explanation:

[tex]\begin{array}{lc}\textbf{Source} &\textbf{Contribution \%} \\\text{Space heating }& 45\\\text{Water heating} &18\\\text{Space cooling} & 9 \\\text{Computers/Electronics} & 6 \\\text{Lighting} & 6 \\\text{Cooking} & 4 \\\text{Refrigeration} & 4 \\\text{Wet cleaning} & 3 \\\text{Other} & 5 \\\end{array}[/tex]

The pie chart is in the Figure below.