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Answer:

The answer is that compounds are formed when elements are joined and held together by strong forces called chemical bonds. ... Covalent bonds share electrons between atoms in order to fill their electron shells. In the compound, molecules are held together by the attraction between the nucleus and the shared electrons.

Millions of compounds can be made from just 100 elements because the atoms of these 100 elements can combine with each other in different ways to produce countless compounds.

A compound is formed when atoms of two or more elements are chemically combined together.

100 elements can combine with each other in many different ways. For instance, carbon combines with almost all the known elements to form unique compounds in each case depending on the arrangement of atoms of elements or type of element in each of the compounds formed.

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Answer:

their warfare had changed dramatically

Answer:

Explanation:

They first tried to build there army. They did this by passing the Selective Service Act. ... In the next 18 months about 4 million men and women joined the army, but then the army had to be educated.

Answer:

Smell: Most chemists can identify solvents by their distinctive smells (though this is a pretty bad idea). ¹

Melting point: If you've got very pure crystals, you can use their melting point to figure out which of several possible chemicals you've got.

Explanation:

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Answer:

the answer to the question is smell

Answer: The TRUE statements about an ion includes:

a. Anions result when atoms gain an electron.

b. Cations have more protons than electrons.

Explanation:

The fundamental unit of matter is ATOM, which is the smallest particle of an element that can take part in a chemical reaction. The constituents of the atom are PROTON, NEUTRON and ELECTRONS.

The theory of the possible model of an atom and the position of each constituent within the atom was given by Lord Rutherford. The nucleus of an atom is made up of the protons and neutron while the electron revolves round it. IONS are formed when these atoms either gains or losses these electrons.

When an atom gains electrons to complete it's outermost shell, it acquires a negative charge. This is because the electrons are more than the protons. This type of atom is called an ANION

When an atom losses an electron, it in turn acquires a positive charge. This is because the proton are more than the electrons. This is called the CATION.

Therefore the true statement about ions is option a and b.

Option C is false because it is an electron that is either loss or gained to form an ion not Neurons. Option D is wrong because Na+ lost one electron to become positively charged.

Answer:

A and C

Explanation:

An ion dipole interaction exists between a molecule having a dipole and an ion. The positive end of the dipole interacts with a negative ion while the negative end of the dipole interacts with a positive ion.

If we look at the options listed, the H-H bond is non polar, hence it can not show ion-dipole interaction.

Similarly, the H-F bond is polar, but the negative end of the dipole (F) is made to interact with a sulphide(negative) ion which is incorrect.

Answer:

Me too

Explanation:

The question is incomplete, the complete question is;

A molecule that contains three identical polar bonds to the central atom will be ________.

nonpolar if the geometry is planar triangular

polar in all cases

nonpolar in all cases

impossible to tell the polarity

either polar or nonpolar depending on the identity of the atoms bonded to the central atom

Answer:

Nonpolar if the geometry is planar triangular

Explanation:

The polarity of molecules depends both on the polarity of individual bonds in the molecule as well as the overall dipole moment of the molecule. We must remember that dipole moment is a vector quantity hence direction of the resultant vector is very important.

Now, if i have a molecule that contains three identical polar bonds, a planar triangular geometry means that the molecule is symmetrical and will have an overall dipole moment of zero. Hence the molecule is nonpolar.

Answer: The final pressure is 12.6 atm

Explanation:

The combined gas equation is,

[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]

where,

[tex]P_1[/tex] = initial pressure of gas = 5.6 atm

[tex]P_2[/tex] = final pressure of gas = ?

[tex]V_1[/tex] = initial volume of gas = v

[tex]V_2[/tex] = final volume of gas = [tex]v-\frac{50}{100}v=0.5v[/tex]

[tex]T_1[/tex] = initial temperature of gas = [tex]-19.0^0C=(-19+273)K=254K[/tex]

[tex]T_2[/tex] = final temperature of gas = [tex]12.0^0C=(12.0+273)K=285K[/tex]

Now put all the given values in the above equation, we get:

[tex]\frac{5.6\times v}{254}=\frac{P_2\times 0.5v}{285}[/tex]

[tex]P_2=12.6atm[/tex]

The final pressure is 12.6 atm

Answer:

The correct answer is - 0 degrees Celsius or 32 degrees  Fahrenheit.

Explanation:

The pure water freezes below zero degrees Celsius and forms ice which is started to melt at zero degrees Celsius as it gets the heat from the surroundings. The change in the heat or temperature of matter leads to a change in the state of matter.

Kate will find that the ice cubes formed from the pure water started to melt at 0 degrees Celsius or 32 degrees Fahrenheit with the help of sensor she has.

Answer:

The answer is 2.4moles of Ag

Explanation:

450.98g Cu(NO3)2/1 x 1mole/187.554g Cu(NO3)2 = 2.4moles Ag

Answer:

[tex]P_2=507.7torr[/tex]

Explanation:

Hello there!

In this case, when we have a gas that is undergoing a change in both pressure and temperature, we utilize the Gay-Lussac's equation as shown below:

[tex]\frac{T_2}{P_2}=\frac{T_1}{P_1}[/tex]

Thus, since we are given the initial pressure and temperature and the final temperature, we can compute the final pressure as shown below:

[tex]P_2=\frac{P_1}{T_1}*T_2[/tex]

So we plug in, by making sure the temperatures are in kelvins, to obtain:

[tex]P_2=\frac{550torr}{(117+273)K}*(87+273)K\\\\P_2=507.7torr[/tex]

Best regards!

Answer:

% = 33.83%

Explanation:

To do a better understanding of this, we can treat the mixture of the combustion as two separate reactions, in that way, we can have an idea of what is happening and how to calculate the mass percent.

So the combustion reactions in this mixture are:

2C₂H₆ + 7O₂ ---------> 4CO₂ + 6H₂O

C₃H₈ + 5O₂ ----------> 3CO₂ + 4H₂O

Now that we have both reactions (And balanced) we can hace an idea of the mole ratio between every compound in the mix.

For practical purposes, let's call "a" the mass of ethane, and "b" the mass of propane. The innitial mix have 9.725 g, so this means that:

a + b = 9.725 g    (1)

Now that we have this, we can write a relation between the moles of oxygen and the moles of the gases. If we have 1.115 moles of oxygen, and also know the mole ratio of oxygen to "a" and "b", so:

moles O₂ = moles a (moles O₂/moles a) + moles b (moles O₂/moles b)   (2)

And we know that moles a and moles b are:

moles a = a / MW

moles b = b / MW

The MW of a is 30 g/mol and the MW of b is 44 g/mol

Replacing the given data we have:

1.115 moles O₂ = (a/30)(7 moles O₂/2 moles a) + (b/44)(5 moles O₂/1 mole b)

1.115 moles O₂ = (0.1167a) moles O₂ + (0.1136b) moles O₂

To keep solving this, we can use expression (1) to solve for b, and then, replace here and have only one equation with 1 incognite:

a + b = 9.725 g  

b = 9.725 - a   (3)

Replacing above we have:

1.115 = 0.1167a + 0.1136(9.725 - a)

1.115 = 0.1167a + (1.1048 - 0.1136a)

1.115 - 1.1048 = 0.1167a - 0.1136a

0.0102 = 0.0031a

a = 3.29 g

Now, that we have the mass of the ethane, we can calculate the mass percent:

% = (3.29 / 9.725) * 100

Hope this helps

Answer:

[tex]1.58\ \text{g}[/tex]

Explanation:

10.11 g sample of [tex]NaBr[/tex] contains 22.34% [tex]Na[/tex] by mass

According to the law of constant composition the if one sample of [tex]NaBr[/tex] has 22.34% of [tex]Na[/tex] by mass then any other sample of [tex]NaBr[/tex] will have the same percentage of the amount of [tex]Na[/tex].

For a sample of 7.09 g we have

[tex]7.09\times \dfrac{22.34}{100}=1.583906\approx 1.58\ \text{g}[/tex]

The mass of sodium in the required sample is [tex]1.58\ \text{g}[/tex].

Answer: B. Allow for movement

Explanation: Because the muscular system is composed of specialized cells called muscle fibers. Their predominant function is contractibility. Muscles, attached to bones or internal organs and blood vessels, are responsible for movement. Nearly all movement in the body is the result of muscle contraction. Make sure to add me as a friend!!! <3 YW!!!

Answer:

The first one is ground and the second one is excited  

Explanation:

Answer:

Explanation:

Entropy is the measure of randomness of a system . When heat is added to a gas , gas molecules become more random and therefore , their entropy increases . Hence at higher temperature , entropy increases and randomness increases due to addition of heat .

Hence when a gas molecules become more ordered that means entropy decreases . Hence heat is withdrawn from the system . Hence temperature of the system is decreases .

In the given case , gas molecules are made more ordered that means their temperature is decreased to lower the  entropy before they are exhausted .

Answer:

Where is the map?

Explanation:

Answer:

On the map, Central and South Asia emerge as the areas of the world where earthquakes are more likely to strike, and with greater intensity.

Explanation:

this means that Asia is the most garenteed to get earthquakes rather than many other places

hope this helps

Answer:

Ions are formed by the addition of electrons to, or the removal of electrons from, neutral atoms or molecules or other ions; by combination of ions with other particles; or by rupture of a covalent bond between two atoms in such a way that both of the electrons of the bond are left in association

The ways Ions may form includes the following

An ion can be defined as an atom or group of atoms possessing an electrical charge. Ions are of two types, they are : Anions which are negatively charged and Cations which are positively charged.

In conclusion,  an ion can be formed by many ways, but a few has been listed above.

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Answer:

546 g NaCI

Explanation:

because 1 mole is equal to 1 moles NaCI or 58.44277 grams.

Answer:

absorbs shock

Explanation:

Answer: absorbs shock

Explanation:

Answer: B) Electronegativity is the attraction an element's nucleus has for the electrons in a chemical bond

Explanation:

Electronegativity is defined as the property of an element to attract a shared pair of electron towards itself.

When the size of an atom decreases as we move across the period, as the electrons get added to the same shell and the nuclear charge keeps on increasing. Thus the electrons get more tightly held by the nucleus.

As, the size of an element decreases, the valence electrons come near to the nucleus. So, the attraction between the nucleus and the shared pair of electrons increases and thus the electronegativity increases.

This question is incomplete, the complete complete question is;

Coulomb's law for the energy of interaction between two charged ions;

E = Ke × q1q2/r

Coulomb's constant Ke = 2.31 × 10⁻²⁸ J.m.

Calculate the bond energy in the ionic compound NaCl if the bond length is 2.36 × 10⁻¹⁰m

Answer:

the bond energy is -9.788 × 10⁻¹⁹ J

Explanation:

Given the data in the question;

Ke = 2.31 × 10⁻²⁸ J.m which is the same as; Ke = 2.31 × 10⁻²⁸ Nm L/c²

ionic compound NaCl;

q1 = charge on Na in NaCl = Na⁺ = + 1C

q2 = charge on Cl in NaCl = Cl⁻ = - 1C

given that bond length r is 2.36 × 10⁻¹⁰m

E = Ke × q1q2/r

we substitute

E = 2.31 × 10⁻²⁸ × (+1 × -1) / 2.36 × 10⁻¹⁰

E = -2.31 × 10⁻²⁸ / 2.36 × 10⁻¹⁰

E = -9.788 × 10⁻¹⁹ J    { The negative sign means Attraction in ions }

Therefore, the bond energy is -9.788 × 10⁻¹⁹ J

Answer:

[tex]0.46[/tex] moles of water were removed from the sample by the heating process

Explanation:

Given

Mass of the evaporating dish [tex]= 6.488[/tex] grams

Mass of the sample of hydrate [tex]= 19.72[/tex] grams

Mass of the sample and dish after heating [tex]= 11.344[/tex] grams

The weight of water removed through evaporation

[tex]= 19.72 - 11.344 = 8.376[/tex] grams

Weight of one mole of water [tex]= 18[/tex] grams

Number of moles of water in [tex]8.376[/tex] Grams of water is equal to

[tex]\frac{8.376}{18} = 0.46[/tex] moles

Answer:

Explanation:

48833.03

Answer: single replacement reaction, [tex]3Sr+2Al(ClO_3)_3\rightarrow 3Sr(ClO_3)_2+2Al[/tex]

Explanation:

A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.

A general single displacement reaction can be represented as :

[tex]XY+Z\rightarrow XZ+Y[/tex]

As strontium metal is added to aluminum chlorate , strontium being more reactive than aluminium, displaces aluminium atom its salt solution and lead to formation of strontium  chlorate and aluminum metal.

[tex]3Sr+2Al(ClO_3)_3\rightarrow 3Sr(ClO_3)_2+2Al[/tex]

Answer:

Number of moles = 0.4626 (Approx)

Explanation:

Given:

Mass of copper = 29.4 gram

Find:

Number of moles

Computation:

Atomic mass of copper = 63.546

Number of moles = Mass / Atomic mass

Number of moles = 29.4 / 63.546

Number of moles = 0.4626 (Approx)

Answer:

You need to add 0.243g of NaOH to raise the temperature back to 16.2°C

Explanation:

Using the equation:

Q = C*m*ΔT

Where Q is heat

C is specific heat

m is mass

and ΔT is change in temperature

We can find the heat required to increase the temperature of the solution back to 16.2°C:

Assuming specific heat of the solution of water + K2SO4 = Specific heat of water:

C = 4.184J/g°C

m = 1.56g + 6.00g = 7.56g

ΔT = 16.2°C - 7.70°C = 8.50°C

Q = 4.184J/g°C * 7.56g * 8.50°C

Q = 268.86J = 0.269kJ of heat are required

As this heat is obtained from the dissolution of NaOH:

0.269kJ * (1mol NaOH / 44.3kJ) = 0.00607 moles of NaOH are required

In grams -Molar mass NaOH: 40g/mol-:

0.00607 moles NaOH * (40g / mol) =

Answer:

C. it is much less because at high pressure the temperature drops

At high pressures, the volume of a real gas  is much less because at high pressures the temperature drops.

Pressure is defined as the force applied on an object perpendicular to it's surface per unit area over which it is distributed.Gauge pressure is a pressure which is related with the ambient pressure.

There are various units by which pressure is expressed most of which are derived units which are obtained from unit of force divided by unit of area . The SI unit of pressure is pascal .

It is a scalar quantity which is related to the vector area element with a normal force acting on it.It is distributed over solid boundaries and across arbitary sections of fluid normal to the boundaries at every point.Usually as the pressure increases ,volume increases.

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the amount of reactants = the amount of products

N2 + 3H2 --> 2NH3

Answer: [tex]LiF[/tex] , [tex]AlCl_3[/tex] and [tex]BeCl_2[/tex]

Explanation:

An ionic bond is formed when an element completely transfers its valence electron to another element. The element which donates the electron is known as electropositive element or the metal and the element which accepts the electrons is known as electronegative element or non metal.

A covalent bond is formed when an element shares its valence electron with another element. This bond is formed between two non metals.

[tex]LiF[/tex] , [tex]AlCl_3[/tex] and [tex]BeCl_2[/tex] contain ionic bonds as they aremade up of metals and non metals.