The enthalpy of formation of water is -285.8 kJ/mol. What can be inferred from this statement?

Answer:

Explanation:

Lithium is the first element in the second period. The second period has a total number of eight elements in all. The number of electrons in a lithium atom is 3.

The electronic configuration of lithium is 1s²2s¹. Lithium has just a single electron in its outermost shell.

Moving from left to right across the second period, the number of electrons in the outermost shell of the elements increases till it reaches the octet i.e 8:

   Be (4) : 1s²2s²

   B (5): 1s²2s²2p¹

   C (6): 1s²2s²2p²

   N (7): 1s²2s²2p³

   O(8): 1s²2s²2p⁴

   F (9): 1s²2s²2p⁵

   Ne(10): 1s²2s²2p⁶

As you go from left to right, the number of valence electrons increases by 1.

From left to right, the number of shell remains fairly constant. Li and Be has one electronic shell each while the rest of the elements in the period have two shells.

As we move from lithium to neon in the periodic table, the elements gain one electron each. Hence, their electron configuration increases sequentially, in line with their increasing atomic number.

When starting with lithium and proceeding to neon across the second period of the periodic table, the atomic number increases from 3 to 10. The atomic number corresponds to the number of protons, which also equals the number of electrons in an atom for a neutral element. Accordingly, as we move from left to right, one observes an increase in the electron configuration, with each subsequent element gaining an additional electron. For instance, the electron configuration of lithium is 1s2 2s1, that of beryllium (the next element) is 1s2 2s2, and so on, till we reach neon with a configuration of 1s2 2s2 2p6. Hence, the number of electrons (and hence electron configuration) increases as we move from lithium to neon.

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Answer:

Explanation:

In gases the particles move rapidly in all directions, frequently colliding with each other and the side of the container. With an increase in temperature, the particles gain kinetic energy and move faster. ... In liquids, particles are quite close together and move with random motion throughout the container.

Gas particles moving through the air due to random motion is called Brownian motion.

Gas have no definite volume and gases have not a definite shape it can take the shape of container in which it filled. Gases can flow easily. They are highly compressible. They have low density. Gases have very weak intermolecular force and very large intermolecular space.

Brownian motion is also called as Brownian movement is defied as the zig-zag motion of particles suspended in a medium. The gas particles moves randomly in Brownian motion.

Thus from the above conclusion we can say that Gas particles moving through the air due to random motion is called Brownian motion.

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Hello There!

This is called a "Chemical Change"

A chemical change is when the composition of a substance changes. There are many signs of chemical changes. When a chemical change occurs, you can see a change in color. When a new color is visible that means that a new substance has been created. There also is a new smell "odor" this hints that a new substance has been formed.

Answer:

PCI3

Explanation:

PCI3 is a product in one reaction and a reactant in the other. This makes it an intermediate as it is produced then used up in the same series of reactions.

Answer: C. PCI3

Explanation:

Answer:

A- Small ice pellets that may fall to the ground in a mixture of rain and snow in the form of a solid

Explanation:

Small ice pellets that may fall to the ground in a mixture of rain and snow in the form of a solid  best describes hail.

Small ice pellets that may fall to the ground in a mixture of rain and snow in the form of a solid describe Hail.

Hail is a form of precipitation, or water that can easily fall to the ground from the atmosphere. Hail is former when water droplets freeze together in the clouds. The ice that formed are called hailstones.

Hailstones length is between 5 millimeters and 15 centimeters

Therefore, Small ice pellets that may fall to the ground in a mixture of rain and snow in the form of a solid describe Hail.

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Answer:

An acid and a Base :)

Explanation:

I just took the test got a 96 A

Answer:

0.422 mol/L.

Explanation:

M = (no. of moles of glucose)/(volume of the solution (L))

M = (mass/molar mass)of glucose / (volume of the solution (L)).

∴ M = (mass/molar mass)of glucose / (volume of the solution (L)) = (289 g/342.2965 g/mol)/(2.0 L) = 0.422 mol/L.

Answer:

Ionic compounds differ from ions in that the overall charge in ionic compounds equals zero while the overall charge in ions is less than or greater than zero. Ions have a superscript number followed by a either a positive or a negative sign. Where both signs appear in the same formula they make it an ionic compound.

Answer:

chlorination

Explanation:

Answer: chlorination

Explanation: DDT is made from the

of unsaturated hydrocarbons.

Answer:

Explanation:

Group           Most Likely Ionic Charge               Number of Valence Electrons

   I                                 +1                                                           1

   II                                 +2                                                         2

   III                                +3                                                          3

   IV                           +4 or -4                                                     4

   V                                  -3                                                         5

   VI                                 -2                                                         6

  VII                                 -1                                                          7

  VIII                                 0                                                          8

For elements in group IV and above, their ionic charge is (8-number of their valence electrons.)

Explanation:

Valence electrons are defined as the electrons which are present in the outermost shell of an atom.

The number of valence electrons in a particular group will be equal to the group number.

Number of valence electrons = Group number

The given table follows:

Group       Most likely ionic charge      No. of valence electrons

   I                                  +1                                            1

  II                                 +2                                            2

 III                                 +3                                            3

 IV                             +4 or -4                                       4

  V                                -3                                              5

 VI                                -2                                              6

 VII                                -1                                              7

VIII                                 0                                             8

Answer:

Na₂CO₃.

Explanation:

The compound that has a common ion effect is Na₂CO₃.

Answer:

Na2Co3

Explanation:

Answer:

Ea = 35 kJ.

Explanation:

Activation energy (Ea) is the difference between the potential energy of intermediate "activated complex/ peak" and reactants.

Ea = P.E. of products - P.E. of reactants = 65 kJ - 30 kJ = 35 kJ.

kindly find the attached image.

Explanation:

Nuclear reactions are defined as the reaction in which there occurs change in the nucleus of an atom due to change in number of protons or neutrons of an atom.

For example, [tex]^{2}_{1}H + ^{2}_{1} \rightarrow ^{4}_{2}He[/tex] is a nuclear reaction.

Hence, identity of the element changes in a nuclear reaction. Also, nuclear reaction can occur at varied rates as they are not affected by temperature, pressure or catalyst.

Whereas a chemical reaction is defined as the reaction where there occurs exchange of electrons between the combining atoms.

For example, [tex]2Na(s) + Cl_{2}(g) \rightarrow 2NaCl[/tex] is a chemical change.

Thus, we can conclude that nuclear reactions are different from chemical reactions as follows.

Answer:

Grahm's law of diffusion states that the rate of diffusion of a gas is inversely proportional to the square root of the mass of its particles.

Molecular weight of NO2 = 46 g mol¹-

Molecular weight of CO2 = 44g mol¹-

Thus the compound which has a lower molecular mass will diffuse at a faster rate than the heavier compound. In this case, the molecular mass of NO2 is more than the CO2 so, NO2 will diffuse at a slower rate than the CO2 molecule.

According to Boyle's law, the temperature would double of a gas if the pressure were halved as the number of moles and the volume were held constant. Hence, option A is correct.

Boyle's law states that at constant temperature, the pressure exerted by a gas is inversely proportional to the volume occupied by it.

If temperature is held constant, the equation is reduced to Boyle's law. Therefore, if you decrease the pressure  (P↓) of a fixed amount of gas, its volume (v ↑) will increase.

(P↓) →  (v ↑)

P∝ [tex]\frac{1}{V}[/tex]

However, if you were to maintain a constant volume while decreasing pressure, the temperature would also have to decrease.

Thus, according to Boyle's law, the temperature would double of a gas if the pressure were halved as the number of moles and the volume were held constant.

Hence, option A is correct.

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Answer:

Ionic or electrovalent bonds

Explanation:

Ionic or electrovalent bonds are interatomic or intramolecular bonds which are formed between two kinds of atoms having a large electronegativity difference usually 2.1.

Electronegativity is the property that combines the ability of an atom to gain or lose electrons. It is expressed as the tendency with which atoms of elements attracts valence electrons in a chemical bond.

In this bond type, a metal transfers its electrons to a more electronegative atom which is a non-metal.

The answer is: a. ionic bonding.

Ionic bond is the electrostatic attraction between oppositely charged ions (cations and anions).  

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For example, compound magnesium chloride (MgCl₂) has ionic bond.  

In this example, chlorine is large company, because it has greater electronegativity than magnesium (small company) and take electrons (assets) from it.

Magnesium (Mg) transfers two electrons, became positive cation, to chlorine (Cl), which became negative anion.  

Magnesium is metal from group 2 and chlorine is nonmetal from group 17 of the Periodic table.  

Electronegativity (χ) is a property that describes the tendency of an atom to attract a shared pair of electrons.

Answer:

prophase I

Explanation:

Homologous chromosomes pair up during prophase I of meiosis.

Answer: C. Primary Consumers

Explanation:

Answer:

Primary consumer.

Explanation:

Food chain may be defined as the sequential flow of food energy from one level to the next tropic level. Producers are the first organism that occupies the first tropic level in the food chain.

Producers prepare their food by themselves. Primary consumers get their food by eating directly the producers. Primary consumers are generally feed on the plants and grass.

Thus, the correct answer is option (C).

Answer:

CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l).

Explanation:

CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g)

2H₂O(g) → 2H₂O(l)

CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l).

Answer:  The reaction is Exothermic

CH4(g) + 2O2(g) > CO2(g) + 2H2O(g) + energy

Explanation:

Answer:

cell wall

chloroplasts

central vacuole

Explanation:

Plant cells have a cell wall, chloroplasts, and a central vacuole. These structures are not found in animal cells.

The structures of three cells present in the cells in plant, but not animal cell are Cell wall, Chloroplast and Plastids.

Animal cell only contain cell membrane whereas plant cell has both cell wall and cell membrane. Unlike animal cell, plant cell makes their own food. The plants come under autotrophs and animals come under heterotrophs.

For this purpose, there is chloroplast in a plant cell. The major function of chloroplast is to produce food through photosynthesis. Plastids are the pigment containing cell organelles which is responsible for the color of plant cell.

The oxidation state of Na decreases from 1 to 0 in this reaction Li (s) + NaOH (aq) → LiOH(aq) + Na(s).

Oxidation state is also called Oxidation number is defined as the number assigned to atoms in molecules to represent the general distribution of electrons.

A chemical reaction is a process in which chemical bonds between atoms to break and reorganize, to form other new substances.

The given chemical reaction is

Li (s) + NaOH (aq) → LiOH(aq) + Na(s)

The oxidation state of Li is zero in the reactant side. The oxidation state of Na in the reactant side is 1. The oxidation state of Li in the product side is 1. The oxidation state of Na in reactant side is 0.

So the oxidation number of Na decreases from 1 to 0.

Thus from the above conclusion we can ay that The oxidation state of Na decreases from 1 to 0 in this reaction Li (s) + NaOH (aq) → LiOH(aq) + Na(s).

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Answer:

Explanation:

The given pH = 8.55

Unknown:

[H₃O⁺] = ?

[OH⁻] = ?

In order to find these unknowns we must first establish some relationship.

                      pH = -log[H₃O⁺]

                   8.55 = -log[H₃O⁺]

                    [H₃O⁺] = inverse log₁₀(-8.55) = 2.82 x 10⁻⁹moldm⁻³

To find the [OH⁻],

                     pH + pOH = 14

                               pOH = 14 - pH = 14 - 8.55

                                pOH = 5.45

              pOH = -log[OH⁻]

               [OH⁻] = inverse log₁₀ (-5.45) = 3.55 x 10⁻⁶moldm⁻³

The solution is basic because it has more concentration of OH⁻ ions compared to H⁺ ions.

They have small differences in electronegativity

i think thats right

Answer:

C.) They have small differences in electronegativity

Answer:

Explanation:

The Electronic Configuration of the elements is the arrangement of all electrons of an element in energy levels and sub-levels (orbitals).  

There are 7 energy levels, numbered from 1 to 7, and in which electrons are distributed, logically in order according to their energy level. Each level is divided into sub-levels. These sub-levels into which each level is divided can be up to 4, called: s, p, d, f. In the sub-level s there can only be a maximum of 2 electrons, in p there can be a maximum of 6 electrons, in the sub-level d 10 electrons and finally in the sub-level f there can be a maximum of 14 electrons.

In level 1 there is only one sub-level, which will be the s. In level 2 there are 2 sub-levels, the s and the p. At level 3 there are 3 sub-levels s, p and d. And at level 4 there are 4 sub-levels, the s, the p, the d and the f.

Aufbau's principle is a principle of atomic physics, which explains how electrons are accommodated in their orbits around the nucleus of the atom. This principle states that the filling of these orbitals occurs in increasing order of energy, that is, from the orbitals of lower energy to those of higher energy.

The simplest of the sub-levels is 1s. If you fill the 1s you can start filling the 2s. After the 2s sub-level is satisfied, the 2p can begin to fill and so on.  

The atomic number Z of the element represents the number of protons of the element, and in a neutral atom it also indicates the number of electrons.  

So, given that the atomic number of the phosphorus is 15, and everything that has been said before, it is possible to say that the electrons that it has in the orbitals will be placed as follows:

1s² 2s² 2p⁶ 3s² 3p³

Finally, the orbital configuration of the phosphorus atom (P) will be as the image shows.

The orbital configuration of the phosphorus (p) atom is attached to the image below.

The phosphorus (P) atom has an atomic number of 15, which means it has 15 electrons. The electron configuration of phosphorus can be determined by filling up the orbitals according to the Aufbau principle and the Pauli exclusion principle.

1s² 2s² 2p⁶ 3s² 3p³, this electron configuration represents the distribution of electrons in the atomic orbitals of a phosphorus atom. The numbers represent the principal quantum numbers (n) and the letters represent the azimuthal quantum numbers (s, p). The superscripts indicate the number of electrons occupying each orbital.

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Answer:

Approximately 1.9 kilograms of this rock.

Explanation:

Relative atomic mass data from a modern periodic table:

To answer this question, start by finding the mass of Pb in each kilogram of this rock.

89% of the rock is [tex]\rm PbS[/tex]. There will be 890 grams of [tex]\rm PbS[/tex] in one kilogram of this rock.

Formula mass of [tex]\rm PbS[/tex]:

[tex]M(\mathrm{PbS}) = 207.2 + 32.06 = 239.26\; g\cdot mol^{-1}[/tex].

How many moles of [tex]\rm PbS[/tex] formula units in that 890 grams of [tex]\rm PbS[/tex]?

[tex]\displaystyle n = \frac{m}{M} = \rm \frac{890}{239.26} = 3.71980\; mol[/tex].

There's one mole of [tex]\rm Pb[/tex] in each mole of [tex]\rm PbS[/tex]. There are thus [tex]\rm 3.71980\; mol[/tex] of [tex]\rm Pb[/tex] in one kilogram of this rock.

What will be the mass of that [tex]\rm 3.71980\; mol[/tex] of [tex]\rm Pb[/tex]?

[tex]m(\mathrm{Pb}) = n(\mathrm{Pb}) \cdot M(\mathrm{Pb}) = \rm 3.71980 \times 207.2 = 770.743\; g = 0.770743\; kg[/tex].

In other words, the [tex]\rm PbS[/tex] in 1 kilogram of this rock contains [tex]\rm 0.770743\; kg[/tex] of lead [tex]\rm Pb[/tex].

How many kilograms of the rock will contain enough [tex]\rm PbS[/tex] to provide 1.5 kilogram of [tex]\rm Pb[/tex]?

[tex]\displaystyle \frac{1.5}{0.770743} \approx \rm 1.9\; kg[/tex].

Answer:119.38 g/mol

Explanation:

Add the Molar mass of each element to get the final answer. Use the Periodic table to find the molar mass. Molar mass is located under neath the elements.

Molecular mass of CHCl3 is 119.5 grams/mole

Molecular mass of CHCl3 = mass of Carbon+ mass of Hydrogen+ 3×(mass of Chlorine)

Molecular mass of CHCl3= 12+1+(3×35.5)= 119.5

Hence The Molecular mass of CHCl3 is 119.5 grams/ mole

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Answer:

[tex]\boxed{ \text{0.75 mol}}[/tex]

Explanation:

(a) Balanced equation

2NaBH₄ + H₂SO₄ ⟶ 2H₂ + Na₂SO₄ + B₂H₆

(b) Calculation

You want to convert moles of NaBH₄ to moles of B₂H₆

The molar ratio is 1 mol B₂H₆:2 mol NaBH₄

[tex]\text{Moles of B$_{2}$H$_{6}$} =\text{1.5 mol NaBH$_{4}$} \times \dfrac{\text{1 mol B$_{2}$H$_{6}$}}{\text{2 mol NaBH$_{4}$}} = \textbf{0.75 mol B$_{2}$H$_{6}$}\\\\\text{The reaction will produce }\boxed{ \textbf{0.75 mol of B$_{2}$H$_{6}$}}[/tex]

Answer:

D. The frictional force overcomes the force that binds the electrons to the atoms, enabling the electrons to move elsewhere

Explanation:

Neutral objects becomes charged by rubbing them together due to the frictional force which overcomes the attractive force holding electrons together in an atom.

Friction is the resistance to flow or movement. When we rub bodies together, the movement of electrons becomes inhibited and this can cause an orbital electron loosely held in an atom to be pulled off as the force of friction increases. This mechanism would result in a body losing electron and another readily gaining that electron as they interact. The loss and gain of electrons causes a neutral body to become charged.

Answer:

its D

Explanation:

To determine the leftover reactant in the combustion of 5.00 grams of oxygen and 5.00 grams of CH4, the limiting reagent calculation shows that the leftover reactant is 3.75 grams of methane as oxygen is the limiting reagent.

To determine the amount of the leftover reactant in a combustion reaction involving 5.00 grams of oxygen and 5.00 grams of CH4, we need to conduct a limiting reagent calculation. The balanced chemical equation for the combustion of methane (CH4) is:

CH4(g) + 2O2(g) → CO2(g) + 2H2O(l)

From the balanced equation, we can see that one mole of CH4 reacts with two moles of O2. The molar mass of CH4 is 16.04 g/mol, and the molar mass of O2 is 32.00 g/mol, so we can use these to convert the mass of each reactant to moles:

Since the reaction requires 2 moles of O2 for each mole of CH4, we can calculate the needed moles of O2 for the reaction with the available CH4:

0.3117 mol CH4 × 2 mol O2 / 1 mol CH4 = 0.6234 mol O2 needed

However, we only have 0.15625 mol of O2 available, which is less than 0.6234 mol. This means O2 is the limiting reagent, and there will be some unreacted CH4 left over. Since all of the oxygen will be used up, we can calculate the leftover mass of methane:

0.15625 mol O2 × 1 mol CH4 / 2 mol O2 = 0.078125 mol CH4 reacted

0.3117 mol CH4 - 0.078125 mol CH4 reacted = 0.233575 mol CH4 unreacted

Finally, we convert the moles of unreacted CH4 back to grams:

0.233575 mol CH4 × 16.04 g/mol = 3.75 grams of CH4

Therefore, the amount of the leftover reactant is 3.75 grams of methane.

Answer:

B

Explanation:

Water molecules are good at forming and breaking hydrogen bonds.

The breaking and reforming of hydrogen bonds in liquid water can absorb a large amount of heat, making water resistant to temperature change.