Solutions
Which statement is true of pure substance

1. They may contain one type of atom or one type of molecules.
2.they can only contain one type of molecules.
3.they can contain different types of atoms and molecules.
4.they can only contain one type of atom

This is science btw

Answer:

you did not give the specific heat like formula like it takes 1kj to raise 28grams of water by 10 grams

Answer:

The ans is : A. Electron, proton, hydrogen atom, helium atom.

An atom consist of sub atomic particles. The order of particles from least massive to most massive is electron, proton, hydrogen atom, helium atom. The correct option is A.

The particles which are smaller in size than the atom are known as the sub atomic particles. An atom generally contains three sub atomic particles, they are protons, electrons and neutrons. The electrons revolve around the nucleus whereas the protons and neutrons are present at the center of the nucleus.

The protons are positively charged particles whereas the electrons are negatively charged. The neutrons are chargeless. The atomic number of 'H' atom is 1 and that of 'He' atom is 2.

The mass of e⁻ is 9.1 × 10⁻³¹ kg, proton is 1.67 × 10⁻²⁷ kg, 'H' atom is 1.66 × 10⁻²⁴ g, 'He' is 4 g. Thus the order is:

electron, proton, hydrogen atom, helium atom

Thus the correct option is A.

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Answer:

The answer is A.

Explanation:

They are both made of amino acids.

Water has relatively strong hydrogen bonds holding the molecules together but CO2 has only dispersion forces acting as intermolecular forces. The weaker intermolecular forces explains why CO2 is a gas whereas H2O is a liquid at room temperature

Answer:

Callable or redeemable bonds

Explanation:

"..are bonds that can be redeemed or paid off by the issuer prior to the bonds' maturity date."

Answer:

This is what could happen:

Explanation:

When lava meets ice, the resulting mess can cause flooding, destroy valuable resources and even produce explosions.

Answer:    When lava meets ice, it neither explodes nor tunnels through; rather, it forms strange-looking bubbles.

Explanation:

Answer:

.06 M NA+

Explanation:

You go from (.02M Na3PO4 / 1) x (3 mole Na+ / 1 mole Na3PO4) = .06 M Na+

Answer:

Explanation:

The new volume can be found by using the formula for Boyle's law which is

[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

From the question we have

[tex]V_2 = \frac{700 \times 120}{1500} = \frac{84000}{1500} = \frac{840}{15} \\ = 56[/tex]

We have the final answer as

Hope this helps you

a.

Ionic bond is a bond in which there is complete transfer of valence electrons between atoms.

The atom that loses the valence electron is called the electron donor while the atom that accepts the electron is called the electron acceptor.

Ionic bond usually occurs between metals and non metals.

Ionic bond is a bond in which there is complete transfer of valence electrons between atoms.

b.

The force of attraction between Na⁺ and Cl⁻ forms the ionic bond.

Since the atoms are now charged, the force of attraction between them forms the ionic bond.

c.

The force of attraction between Mg²⁺ and O²⁻ forms the ionic bond.

Since the atoms are now charged, the force of attraction between them forms the ionic bond.

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An ionic or electrovalant bond is a type of chemical bond, which is formed  from two ions (charged atoms by loosing or gaining electrons) having opposite charges.

Ionic bonds are formed from the transfer of electrons from one atom to another. As the electrons are transferred there occurs a positively charged ions (cations) and a negatively charged ions (anions). These ions are held together in a crystal lattice structure by the strong electrostatic attraction between the positively charged cations and negatively charged anions.

The electrons are transferred as the atoms have tendencies to achieve a stable electronic configuration. They do this to attain a stable atomic structure. By transferring the electrons they attain their octet or duplet.

Sodium chloride(NaCl) is formed when the atom of sodium combines chemically with chlorine atom to generate an ionic compound.

Since sodium has an atomic number of 11, its electronic configuration is 2, 8, 1. There is only one electron in the outermost shell of a sodium atom. Therefore, the sodium atom gives one electron to produce the sodium ion Na⁺.

Chlorine has an atomic number of 17. Hence, its electronic configuration is 2, 8, and 7. The chlorine atom contains seven electrons in its outermost shell and requires one more electron to create the inert gas’s stable, eight-electron configuration. Consequently, a chlorine atom accepts one electron and creates the negatively charged chloride ion (Cl⁻).

When sodium interacts with chlorine, it donates its outermost electron to the chlorine atom, forming a sodium ion (Na⁺) and a chloride ion (Cl⁻) by accepting an electron. The strong electrostatic force of attraction between the newly created ions, holds sodium and chloride ions together to create sodium chloride, Na⁺Cl⁻ or NaCl.

Similarly in the case of Magnesium Oxide (MgO) is formed from the chemical interactions of Magnesium and oxygen atoms, leading to the formation of an ionic compound.

Since magnesium has an atomic number of 12, its electrical configuration is 2, 8 and 2, there is just 2 electrons in the outermost shell of a Magnesium atom. Therefore, the magnesium atom gives two electron to produce the Magnesium ion Mg²+ .

Oxygen has an atomic number of 8. Hence, its electronic configuration is 2 and 6, the oxygen atom contains 6 electrons in its outermost shell and requires 2 more electron to create the inert gas’s stable, eight-electron configuration. Consequently, a oxygen atom accepts 2 electronelectrons and creates the negatively charged oxide ion (O²-).

When magnesium interacts with oxygen, it donates its outermost electrons to the oxygen atom, generating a Magnesium ion Mg²+ .  And an oxygen ion (O²⁻) by acquiring 2 electrons. The attractive electrical force holds magnesium and oxygen   ions together to create sodium chloride,        Mg²⁺ O²⁻ or MgO.

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Answer:

The mass of an atom based on the mass of an atom of carbon-12

Explanation:

Answer:

[tex]\boxed {\boxed {\sf 5.6 \ L \ O_2}}[/tex]

Explanation:

We are asked to find the volume of 0.25 moles of oxygen gas.

At standard temperature and pressure or STP, one mole of any gas has a volume of 22.4 liters.

We want to convert 0.25 moles of oxygen gas or O₂ to liters. We will use dimensional analysis, so we must set up a conversion factor.

[tex]\frac {22.4 \ L \ O_2}{1 \ mol \ O_2}[/tex]

We are converting 0.25 moles of oxygen gas, so we multiply the conversion factor by this value.

[tex]0.25 \ mol \ O_2 *\frac {22.4 \ L \ O_2}{1 \ mol \ O_2}[/tex]

The units of moles of oxygen gas cancel.

[tex]0.25 *\frac {22.4 \ L \ O_2}{1 }}[/tex]

[tex]0.25 * 22.4 \ L \ O_2[/tex]

[tex]5.6 \ L \ O_2[/tex]

0.25 moles of oxygen gas occupy 5.6 liters at standard temperature and pressure.

Answer:

lower th

Explanation:

Pb{Cl}_{2})$ is an inorganic

answer:

lower the temperature so the lead chloride settles out of solution

compound which is a white solid under ambient conditions. It is one of the most important lead-based

reagents. It is poorly soluble in water. And it is insoluble in cold water. Sodium chloride is ssolble at all temperature

so lower the temperature

Explanation:

In SO2 , the bond angle is 119^∘ whereas in SO3 , the bond angle is 120^∘ .H2S = 92.1°

Answer:

In SO2 , the bond angle is 119^∘ whereas in SO3 , the bond angle is 120^∘ .

Explanation:

S atom in both SO2 and SO3 is sp^2-hybridized.

There are 3 bonding sets of electrons and one non-bonding pair on the sulphur. So the shape is based on a tetrahedral structure - but the extra repulsion of the non-bonding pair will decrease the O-S-O angles by a few degrees from the 'perfect' tetrahedral angle.

The bonding in SO3 can be described as a combination of 3 resonance forms of 1 double and 2 single bonds. The SO2 molecule has a dipole moment, The starting point of 109.5 degrees is only applicable for 4 electron regions round the central atom. In SO2, we have 2 double bonds and one lone pair ; 3 electron regions so the default angle is 120 degrees. The extra repulsion of the lp vs double bonds accounts for reduction to 119. S atom in both SO2 and SO3 is sp2-hybridized. But it is related to dipole moment and assertion is the explanation from bent angle so here reason is unable to give explanation of assertion.

Answer:

I believe not.

Explanation:

From what I have been told atoms can never come into contact beyond the electron barrier.

Considering the definition of intermolecular bond, the correct answer is second option: Both the melting point and boiling point are lower.

The molecules of covalent compounds can be held together through electrostatic interactions known as "intermolecular forces", which are characterized by holding more than one molecule together. Therefore, they are related to chemical bonds, which have the goal of making molecules stick together or separate.

In other words, intermolecular forces or bonds are those interactions that hold molecules together. These are electrostatic forces.

The presence of these forces explains, for example, the properties of solids and liquids.

They differ from intramolecular forces, because of these, they correspond to interactions that hold the atoms in a molecule together. In general, intermolecular forces are much weaker than intramolecular forces.

On the other side, the melting point is the temperature at which a substance goes from solid to liquid at a given pressure. Similarly, the boiling point is the temperature at which the substance passes from a liquid to a gaseous state.

Finally, the more intense the intermolecular forces, the higher the melting point and the boiling point of a substance because these are the forces that must be overcome to separate them.

In summary, the correct answer is second option: Both the melting point and boiling point are lower.

Learn more:

Answer:

complementary colour

Explanation:

The complementary colors are used for the light that is transmitted when complex ions absorb wavelength of visible light.

Complementary colors are color pairs that cancel each other whenever combined and mixed, resulting in a grayscale color either white or black. They offer the most contrast for the those two hues when put adjacent to each other. Colors that are complementary are sometimes known as "opposite colors."

Light, often known as visible light, is electromagnetic radiation that falls within the region of the electromagnetic spectrum which the human eye can perceive.

Therefore,  the complementary colors are used for the light that is transmitted when complex ions absorb wavelength of visible light.

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Answer:

No diagram no help

Explanation:

Answer:

O-H

Explanation:

It is polar covalent bond, because the hydrogen atom has electronegativity about 2.6, and the oxygen atom, electronegativity about 3.6. When the difference in electronegativity of the atoms is between 0.4 and 1.7, the result is a polar covalent bond.

Explanation:

According to Charles law : V/T=k (constant).

the volume temperature relationship will be

V/T = 117.5/25 = 4.7

hope this helps you.

Denitrifying Bacteria such as Pseudomonas aeruginosa is the type of bacteria that use enzyme nitrate reductase to metabolise nitrogen oxides to nitrogen gas.

Denitrification is the process whereby nitrites or nitrogen oxides is converted to nitrogen gas by a denitrifying Bacteria such as Pseudomonas.

Pseudomonas aeruginosa uses enzyme nitrate reductase to reduce nitrate to nitrite.

Then nitrite is then converted back to nitrogen gas.

Therefore, Pseudomonas aeruginosa is a type of bacteria that uses enzyme nitrate reductase.

Fireworks need an oxidizer, fuel, and a chemical mixture to produce the colour in the sky. Therefore, option (A) is correct.

The chemicals which are used in crackers are the main reason for the colours in the sky. The colours in the fireworks come from different compounds which are the binder and the colourant. The colourant chemicals provide the colours in the firework while the binder is the agent that binds the fuel and is responsible to burn up the colourant in the firework.

The colourants in the firecrackers can be generated with the use of various metallic salts. These salts can be defined as iconic compounds which possess an anion or an acid and a cation or a base. The metal salts are responsible for generating intense colours when they are burned.

For example, if use calcium salts in the firework will produce an orange colour, and copper salts will produce a bright blue colour.

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Under Normal Conditions no reaction will be seen between Calcium ions (Ca⁺), NaCl (salt solution) and NaOH(sodium hydroxide).

In a double replacement reaction , the compounds present switch cation and anion to form new compounds.

But here in NaOH(sodium hydroxide) and NaCl (salt solution) the cation sodium ion Na⁺, of both the compounds is same so the end result will be same .

There will be no net reaction .

But if excess Sodium Hydroxide is added to the solution , we will see precipitate of NaCl , salt forming.

If Salt contained Ca⁺ ions , firstly NaCl will only combine with Ca⁺ ions in special conditions as Na⁺ ions are more reactive than Ca⁺ ions.

On addition of NaOH we would observe no change in normal conditions due to above stated reason .

In special conditions following reaction takes place ,in normal condition the reaction follows reverse direction.

Ca + 2 NaOH ← Ca(OH)₂ + 2 Na

Hence under Normal Conditions no reaction will be seen between Calcium ions , NaCl (salt solution) and NaOH(sodium hydroxide).

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MgCl2 product in the reaction forms a precipitate because it is solid an insoluble salt and not dissolve in solution and precipitate on the bottom surface of the solution.

The chemical reaction in which two ionic bond combine to form an insoluble salt in a aqueous solution is called precipitation reaction.

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An endothermic process may be spontaneous if: C. the product particles have more freedom of motion than the reactant particles.

An endothermic reaction can be defined as a type of chemical reaction in which heat energy is absorbed from the environment.

Generally, heat energy is absorbed in a chemical reaction when the energy of the products is greater (more) than the energy of the reactants and this is referred to as an endothermic reaction.

Similarly, an endothermic process may be spontaneous when the product particles have more freedom of motion than the reactant particles.

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246800 tons of sulfur dioxide was emitted by the utility company who burned 6.17 million tons of coal.

6.17 million tons of coal contain 2.00% sulfur, hence the weight of sulfur is:

Weight of sulfur = 2% of 6.17 million tons = 0.02 * 6170000 = 123400 tons

123400 tons of sulfur is found in 6.17 million tons of coal

The weight of sulfur dioxide is twice that of sulfur, hence:

Amount of sulfur dioxide emitted = 2 * 123400 tons  = 246800 tons

246800 tons of sulfur dioxide was emitted.

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Explanation:

each of more than one hundred substances that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e. the number of protons in the nuclei of its atoms.