Help! Please! Fast! Please!

Answer:

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative at 0.7.

Explanation:

Major periodic trends include: electronegativity, ionization energy, electron affinity, atomic radius, melting point, and metallic character. ... These trends exist because of the similar atomic structure of the elements within their respective group families or periods, and because of the periodic nature of the elements

Answer:

B) +2; 6; -2

Explanation:

In order to know what the coordination number is, all we need to do is to count the number of ligands present in the coordination sphere. Coordination number refers to the number of ligands in the coordination sphere of a given complex. The coordination number here is 6.

The counter ion here is 2Na+. It means that the overall charge on the complex must be -2 because the magnitude of charge on the complex ion is exactly balanced by the number of counter ions.

The charge on the metal (x) must now be;

x + 0 + 4(-1) = -2

x - 4 = -2

x = -2 + 4

x = +2

Note that NH3 is designated as zero because it is a neutral molecule. Each NCS^- ion has a charge magnitude of -1.

Answer:

x = w/v

General Formulas and Concepts:

Pre-Algebra

Explanation:

Step 1: Define

v = w/x

Step 2: Solve for x

The statement that describes a physical change is a sculptor casts a statue in molten bronze and allows it to harden. The correct option is C.

"A physical change is one that simply affects the physical nature of the substance." Usually, increasing the temperature or applying pressure, both, will cause a physical change. In other words, physical changes are reversible.

All the other options like rusting of iron bolts on a bridge is a chemical change when iron reacts with oxygen in the air, it gets rust.

Similarly, silver cups exposed to air react with air is a chemical change, and option d, silver off magnesium that creates light, is also a chemical change.

Thus, the correct option is C. A sculptor casts a statue in molten bronze and allows it to harden.

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Answer:

Water from melting snow or rainfall infiltrates into cracks in rocks. ... As this process of freezing and thawing happens repeatedly, the rock begins to weaken and eventually breaks apart into angular fragments.

Explanation:

Water melting from snow or rainfall which infiltrates into cracks in rocks,  this is repeated process of freezing and thawing,  the rock begins to weaken and eventually breaks apart into angular fragments.

A rock can be formed due to the aggregation of mineral constituents in the earth’s crust and  it can be classified is based on different factors like Geological classification, Physical classification, Chemical classification.

Geological classification can be either Sedimentary rock formed by the deposition of sediments by the weathering of pre-existing rocks and it can be carried out by various agents like water, wind, gravity, etc.

Igneous rocks formed  by the  solidification of magma below the earth’s surface which is held together below the earth’s surface and unable to descend, when these magma cools down  and solidifies into igneous rocks.

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Answer:

The phosphorus ylide reacts with the aldehyde or ketone to make an oxaphosphetane.

Explanation:

The Wittig reaction is a reaction that occurs between a phosphorus ylide and an aldehyde or ketone. The final products are an alkene and triphenyl phosphine oxide.

The first step in the reaction is the attack of the phosphorus ylide on the aldehyde or ketone. This is followed by attack of oxygen on phosphorus to form a [2+2] cycloaddition product (oxaphosphetane)  which  decomposes to form the alkene and triphenylphosphine oxide.

Explanation:

Kendrick gave the bat potential Energy

Answer:

A

Explanation:

I took a test like this and my teacher said this was right so ye. hopefully I remembered correctly if its wrong im sorry ;C

Answer: A

Explanation: A thunderstorm forms when warm, moist air rises into cold air. Hope this helps. :)

Answer:

an electromagnetic wave

Explanation:

Answer:

Suns gravity

Explanation:

Answer: 2021

B

The Sun's gravity

Explanation: Just took the big test

Answer: Since k2 corresponds to 64 hours, the time for the milk to sour at 40 C is 64 h / 9.38 = 6.8 hours.

Explanation:

At temperature T1, the Arrhenius Equation is:

k1 = Ae^(-Ea/RT1).

An equivalent equation can be written at T2:

k2 = Ae^(-Ea/RT2).

If these equations are divided, then A cancels:

k1/k2 = e^(-Ea/RT1)/e^(-Ea/RT2)

Taking the natural log:

ln(k1/k2) = (Ea/RT2)-(Ea/RT1);

or:

ln(k1/k2) = (Ea/R)(1/T2 - 1/T1)

We can infer from the question that the milk sours 3 times as fast at the higher temperature (let's call it T1), so we can arbitrarily call k2 = 1 and k1 = 3.

a) Substitute:

ln(3) =  (Ea/R)(1/276.15 K - 1/293.15 K).

We get Ea/R = 5231.6. Multiply this by whatever value of R you choose to get Ea in your favorite energy unit. Remember the sig figs.

b) Again, let's let the lower temperature = T2, since we have defined k2 = 1:

ln(k1) = (5231.6)(1/276.15 K - 1/313.15);

ln(k1) = 2.24, so k1 = 9.38.

Since k2 corresponds to 64 hours, the time for the milk to sour at 40 C is 64 h / 9.38 = 6.8 hours.

This is an example of #2, conduction.

Conduction is the process where heat energy is transmitted through collisions between atoms or molecules.

The equation is balanced. There are 4 aluminium atoms and 6 oxygen atoms on each side.

Answer:

Melting point

Explanation:

it's constant temperature at which the bonds of a solid Crystal lattice are broken down by overcoming the attractive forces converting it to liquid

Answer:

a.Neon

b.carbon

c potassium

Answer:

A) the CH3 group

Explanation:

Answer:

E

because it forms the ionic bond but not covalent.

Answer:

NaF, CaBr2, MgO

Explanation:

Hi! For this problem, you are going to want to look at the charges of the elements in order to write their formulas.

NaF: Na has a charge of +1 and F has a charge of -1. This means that they have a 1:1 ratio and the formula is written as such - NaF.

CaBr2: Ca has a charge of +2 and Br has a charge of -1. For this problem you want to make sure that their formal charge (the charge of the entire molecule) equals 0. This means that the negative charges need to equal the positive charges. Looking at this, you are going to need to Br ions with a charge of -1 to equal one Ca ion with a charge of +2 - CaBr2.

MgO: Mg has a charge of +2 and O has a charge of -2. This means that they have a 2:2 ratio which simplifies to a 1:1 ratio and the formula is written as such - MgO.

Hope this helps!

Answer:

Coefficients represents no of moles while subscripts represent no of atoms.

Answer:

Coefficients came before formula . Example = 4CO means there are 4 molecules of carbonmonooxide.

Subscripts came after and below the formula . Example = Oxygen gas in which 2 is a subscript which means there are 2 atoms of Oxygen in 1 molecule of Oxygen i.e. oxygen gas

Hi

i hope this helps

Answer:

The Greek atom theory

Explanation:

The concept of the Greek atomos theory is an indivisible particle of matter, goes back to ancient Greece and a man named Democritus held that all matter could be subdivided only until some finite particle was reached.

Answer: 1.38

Explanation:

Gay-Lussac's Law: This law states that pressure is directly proportional to the temperature of the gas at constant volume and number of moles.

[tex]P\propto T[/tex]     (At constant volume and number of moles)

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

where,

[tex]P_1[/tex] = initial pressure of gas  = 841 mm Hg

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

[tex]T_1[/tex] = initial temperature of gas  =[tex]14.7^0C=(14.7+273)K=287.7K[/tex]  

[tex]T_2[/tex] = final temperature of gas = [tex]84.7^0C=(84.7+273)K=357.7K[/tex]  

[tex]\frac{841}{287.7}=\frac{P_2}{357.7}[/tex]

[tex]P_2=1045.6mm Hg=1.38atm[/tex]    ( 760 mm Hg = 1atm )

Thus the final pressure is 1.38

it is push i think to move the car

Answer:

Either A. Push or B.Pull because the truck is either pushing or pulling the car to move it. So it depends on if it's pushing or pulling the car.

Explanation:

Answer:

[tex]CaS[/tex]

Explanation:

Hello!

In this case, since calcium's oxidation state when forming ionic bonds is +2 and sulfur's oxidation state when bonding those bonds is -2, for the required formula we write:

[tex]Ca^{2+}S^{2-}[/tex]

Now, since they have the same charge number, we infer the ionic compound formed when they bond is calcium sulfide:

[tex]CaS[/tex]

Best regards!

Answer:

Chemical, cause physical are changes affecting the form of a chemical substance, but not its chemical composition. This doesn't affect the substance but the composition.

Explanation:

Answer:

the answer is b

Explanation:

brcause the gravutational pull on the moon is lower than on earth...

Answer:

a)NaBr

b)FCl

Explanation:

To identify which compound is more ionic we will calculate the electronegativity difference.

A) NaBr

Electronegativity of Na = 0.93

Electronegativity of Br = 2.96

Electronegativity difference = 2.96- 0.93 = 2.03

HBr

Electronegativity of H = 2.2

Electronegativity of Br = 2.96

Electronegativity difference = 2.96 - 2.2 = 0.76

NaBr have more ionic character because of large electronegativity difference.

B) BrCl

Electronegativity of Cl = 3.16

Electronegativity of Br = 2.96

Electronegativity difference = 3.16 - 2.96 = 0.2

FCl

Electronegativity of F = 3.98

Electronegativity of Br = 2.96

Electronegativity difference = 3.98 - 2.96 = 1.02

FCl have more ionic character because of large electronegativity difference.

Answer:

Explanation:

An atom is the smallest unit of an element that can take part in a chemical reaction. Atoms are made up of protons, neutrons and electrons. Atoms can exist as a monoatomic (such as in the case of Helium, Xenon and Neon) or as diatomic (such as in the case of oxygen and nitrogen). Atoms take part in a chemical reaction and there reactivity varies among themselves.

From the above, it can be deduced that atoms have protons, neutrons and electrons. The number of protons (which is positively charged) of an atom determines it's position on the periodic table because elements in the periodic table are arranged according to the number of protons (called atomic number). The electron(s) present in the outermost shell of each atom (called valence electrons) determines there chemical reactivity. What happens here is that, all atoms (except noble gases) want to achieve there duplet or octet configuration so as to become stable. This octet configuration means they want to have there outermost shell completely filled (with eight electrons or two electrons for duplet). They usually achieve this configuration by taking part in chemical reactions. Thus, when an atom has just one electron in it's outermost shell, it becomes easy to lose it to another atom by way of interacting with it in a chemical reaction. When it loses this single electron (valence electron) in it's outermost shell, it becomes stable with the inner completely filled shell (that would be the new outermost shell). Examples include Lithium, sodium and potassium. Sodium (with eleven electrons and three shells) would lose the single electron in it's outermost shell so as to have just two shells with the second shell completely filled with eight electrons. Thus, the more the valence electron to be lost to achieve the octet structure, the lesser the reactivity of the atom.

Also, an atom that has just one electron to complete it's own outermost shell and thus achieve it's octet structure is also highly reactive. This is also because it is easy for this atom to receive a single electron and become completely filled. Examples include chlorine, fluorine and iodine. Fluorine (with nine electrons and two shells) will easily accept one more electron so as to achieve it's octet structure with a completely filled outermost shell (of eight electrons). Thus, the lesser the electrons to be gained to achieve the octet configuration, the higher the chemical reactivity of such atoms. Noble gases have extremely low or no reactivity at all for this reason because it has a completely filled outermost shell (no losing or donating).

It should also be noted that metals (which are found on the left of the periodic table) exist as monoatomic while gases (which are found on the right), with the exception of noble gases, are mostly diatomic.

The reactivity of atoms of elements in the periodic table depends on their valency as well as their position in the periodic table.

The periodic table contains an arrangement of atoms in order of increasing atomic numbers. Elements in the periodic table are arranged in groups. Each group of elements have atoms that contain the same number of valence electrons.

Atoms of alkali and alkaline earth metals as well as atoms of halogens are highly reactive. This has something to do with the number of valence electrons they contain. The alkali and alkaline metals give out their electrons easily are high reactive while the halogens accept electrons easily are also highly reactive.

Alkali and alkaline earth metals have a few valence electrons so they give them out easily. Halogens have seven valence electrons hence they accept electrons easily. Reactivity of metals generally decreases from left to right in the periodic table while the reactivity of nonmetals increases from left to right. The elements of group 18 are placed in the last group because they are unreactive.

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Answer:

1. 0.28M

2. 24mL

3. 0.002295moles of NaOH.

Explanation:

1. The 6.0M HCl solution is diluted from 35mL to 750mL, that is:

750mL / 35mL = 21.43 times

The 6.0M HCl solution is diluted 21.43 times, the final concentration is:

6.0M / 21.43 = 0.28M

2. First, we need to convert grams of CuNO3 to moles and then, as molarity is moles per liter we can solve for volume of solution in liters and convert it to mililiters:

Moles CuNO3 -Molar mass 124.9g/mol:

2.49g * (1mol / 124.9g) = 0.020 moles of CuNO3

Volume is:

0.020 moles * (1L / 0.830mol) = 0.0240L * (1000mL / 1L) = 24mL

3. In 13.5mL = 0.0135L of 0.17M NaOH the moles are:

0.0135L * (0.17mol / L) = 0.002295moles of NaOH

Answer:

The major innovation made from Abacus to the present fifth generation​ is explained below in details.

Explanation:

Industrial Age - 1600

John Napier, a Scottish noble and diplomat consecrated much of his holiday time to the learning of mathematics. He was particularly engrossed in devising methods to aid estimates. His most famous offering was the discovery of logarithms. He listed logarithmic measures on a set of 10 board rods and thus was capable to do multiplication and division by equaling up numbers on the poles. These became recognized as Napier’s Bones.

There are 1.204 x 10¹⁹ atoms O

The empirical formula is the smallest comparison of atoms of compound forming elements.  

A molecular formula is a formula that shows the number of atomic elements that make up a compound.  

1 mol of molecule Na₂C₂O₄ :

There are 4 mol of O in 1 mol of molecule Na₂C₂O₄

So for 5 x 10⁻⁶ mol Na₂C₂O₄ :

[tex]\tt mol~O=4\times 5.10^{-6}=2.10^{-5}[/tex]

1 mole = 6.02.10²³ particles , so number of atoms O :

[tex]\tt 2\times 10^{-5}\times 6.02\times 10^{23}=1.204\times 10^{19}[/tex]