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Answer:

S (sulphur)

Explanation:

In a neutral atom, the number of electrons and the number of protons in an element are equal. These numbers are called the ATOMIC NUMBER. That is, in a neutral atom;

proton no. = electron no. = Atomic no.

Hence, in this case where phosphorus atom has an electron number of 15. It means that there are 15 protons and 15 electrons in a phosphorus atom. If one electron is added to these electrons i.e. 15 +1, there will be 16 electrons in the atom, hence, this atom becomes SULPHUR element, which has 16 electrons in its atom, with chemical symbol S.

Answer:

Second element(Titanium); [Ar] 3d2 4s2

Third element(Vanadium):Ar 3d3 4s2

Explanation:

Given that there are only three d orbitals in universe L instead of five, the electronic configuration of the second and third elements in the first transition series will now look thus;

Second element(Titanium); [Ar] 3d2 4s2

Third transition element(Vanadium):Ar 3d3 4s2

Hence, the electronic configuration of Titanium and Vanadium in universe L is just the same as what it is on earth.

Answer:

Electron

Explanation:

the answer is mitosis

Answer:

D

Explanation:

Human activities that contribute to desertification include the expansion and intensive use of agricultural lands, poor irrigation practices, deforestation, and overgrazing. ... Some meteorologists and soil scientists measure the impacts and length of a drought to determine if it is an example of desertification.

Answer: 0.125 moles F2

Explanation: 1.5x1023 atoms of F = 0.75x10^23 molecules F2

moles F2 = 0.75x10^23/avogadro number = 0.125 moles

There are 0.25 moles in 1.5 x [tex]10^{23}[/tex]  atoms of fluorine.

Given,

In one mole we have,

6.02 x [tex]10^{23}[/tex] atoms.

1 mole = 6.02 x [tex]10^{23}[/tex] atoms

Find the number of moles in 1.5 x [tex]10^{23}[/tex] atoms of fluorine.

We have,

1 mole = 6.02 x [tex]10^{23}[/tex] atoms

Multiply  1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] on both sides

1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] x 1 mole = 1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] x 6.02 x [tex]10^{23}[/tex] atoms

1.5/6.02 mole = 1.5 x [tex]10^{23}[/tex]  atoms

0.25 moles = 1.5 x [tex]10^{23}[/tex]  atoms.

Thus there are 0.25 moles in 1.5 x [tex]10^{23}[/tex]  atoms of fluorine.

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Answer:

a

Explanation:

they have to have the same numbers on each side.

According to the law of conservation of mass, the total mass in the product side is equal to the mass in the reactant side of a reaction. Thus, option A that is The products must contain the same number and same types of atoms as the reactants is correct.

Mass conservation is similar to law of energy conservation. That is mass can neither be created nor be destroyed. Thus The total mass in a system is conserved. Therefore,in reaction the mass of product have to be  equal to the mass of reactant.

A balanced reaction represent all reactants in their state and in perfect stoichiometry. Hence, each elements have to be equal in number on both side. No new atoms is created here and no atom is lost.Same number and same type will be in both side.

During a chemical reaction, the regrouping of atoms occurs to form the new product. Hence, no new atoms are added . Therefore The products must contain the same number and same types of atoms as the reactants and satisfies the mass conservation.

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Answer: I'm not sure if you have a selection of choice but I think it's A. Female deer have no need for antlers.

Explanation: I mean they don't.. Even if the Male are older that doesn't stop a female deer from growing antlers.. Just flimsy one's I guess.

In an ecosystem, as the growth of antlers is controlled by genes male  male whitetail deer grow antlers but females seldom grow antlers.

Ecosystem is defined as a system which consists of all living organisms and the physical components with which the living beings interact. The abiotic and biotic components are linked to each other through nutrient cycles and flow of energy.

Energy enters the system through the process of photosynthesis .Animals play an important role in transfer of energy as they feed on each other.As a result of this transfer of matter and energy takes place through the system .Living organisms also influence the quantity of biomass present.By decomposition of dead plants and animals by microbes nutrients are released back in to the soil.

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Answer:

Female

Explanation:

Answer: A. Female.

Explanation: The word 'heroine' means a female or a woman that is admired and looked upon for her courage, bravery, and noble qualities.

Answer:

D

Explanation:

Craters produced by the collision of a meteorite with the Earth (or another planet or moon) are called impact craters. The high-speed impact of a large meteorite compresses, or forces downward, a wide area of rock. The pressure pulverizes the rock.

The unknown substance : Lead

Given

Density of element

mass of unknown substance = 40 g

volume = 3.5 cm³

Required

The density of unknown substance

Solution

Density is the ratio of mass per unit volume  

The unit of density can be expressed in g/cm³ or kg/m³  

Density formula:  

[tex]\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}[/tex]

Input the value to find the density of an unknown substance :

ρ = 40 g : 3.5 cm³

ρ = 11.43 g/cm³

If we look at the table, the substance which has a density of 11.43 is Lead

Answer:

its electron

Explanation:

i dont have an explanation but i hope you get it right

Answer: Across each row, or period, of the periodic table, the number of valence electrons in groups 1–2 and 13–18 increases by one from one element to the next. Within each column, or group, of the table, all the elements have the same number of valence electrons.

Relationship between the period number and the number of valence electrons:

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Answer:

Mass = 0.697 g

Explanation:

Given data:

Volume of hydrogen = 1.36 L

Mass of ammonia produced = ?

Temperature = standard = 273.15 K

Pressure = standard = 1 atm

Solution:

Chemical equation:

3H₂ + N₂       →      2NH₃

First of all we will calculate the number of moles of hydrogen:

PV  = nRT

R = general gas constant = 0.0821 atm.L/mol.K

1atm ×1.36 L = n × 0.0821 atm.L/mol.K × 273.15 K

1.36 atm.L = n × 22.43 atm.L/mol

n = 1.36 atm.L / 22.43 atm.L/mol

n = 0.061 mol

Now we will compare the moles of hydrogen and ammonia:

                 H₂         :          NH₃

                  3          :            2

                0.061     :         2/3×0.061 = 0.041

Mass of ammonia:

Mass = number of moles × molar mass

Mass = 0.041 mol × 17 g/mol

Mass = 0.697 g

Answer:

The periodic table helps organize all the elements found in the world and tells a great deal of information on each of the elements such as their atomic mass, symbol, atomic number, and more. It even is organized into groups (columns) and periods (rows). The elements in the same group mostly have similar chemical properties. In short, the periodic table is a list of the elements that make up the world around you.

Explanation:

Answer:In ionic compounds, electrons are transferred between atoms of different elements to form ions. But this is not the only way that compounds can be formed. Atoms can also make chemical bonds by sharing electrons equally between each other. Such bonds are called covalent bonds. Covalent bonds are formed between two atoms when both have similar tendencies to attract electrons to themselves (i.e., when both atoms have identical or fairly similar ionization energies and electron affinities). For example, two hydrogen atoms bond covalently to form an H2 molecule; each hydrogen atom in the H2 molecule has two electrons stabilizing it, giving each atom the same number of valence electrons as the noble gas He.

Compounds that contain covalent bonds exhibit different physical properties than ionic compounds. Because the attraction between molecules, which are electrically neutral, is weaker than that between electrically charged ions, covalent compounds generally have much lower melting and boiling points than ionic compounds. In fact, many covalent compounds are liquids or gases at room temperature, and, in their solid states, they are typically much softer than ionic solids. Furthermore, whereas ionic compounds are good conductors of electricity when dissolved in water, most covalent compounds are insoluble in water; since they are electrically neutral, they are poor conductors of electricity in any state.

Answer:

Extinction

Explanation:

When a species becomes extinct, every last specimen has died out

Answer :

B. Most wind erosion happens in deserts, beaches, and plowed fields.

Answer:

Yes, because it match the octet rule!!

It is double bond lewis structure of ch2s!!

Explanation:

Answer:

The answer is CH4<CH3OCH3<CH4O<CaCO3

Explanation:

The order of the lowest to highest normal boiling point:

H₂ < O₂ < H₂CO₃ < H₂O < CaO

The boiling point is the temperature at which the vapor pressure of the liquid becomes equal to the atmospheric pressure.  At this temperature, the liquid phase is changed into a vapor phase.

The boiling point is the temperature point at which the material transforms into the gas phase in the liquid phase. The Celsius scale was created on the basis of the ice or water melting point and the liquid water or vapor boiling point. Each substance consists its own boiling point.

The boiling point of Calcium oxide is 2850° C as it has a strong force of attraction between the ions. The boiling point of water as we already know is equal to 100° C.

The boiling point of the oxygen gas is -183°C and the boiling point of the hydrogen gas is  - 252.8°C.  The boiling point of carbonic acid is 333.6°C.

Therefore, CaO has the highest, and hydrogen gas has the lowest normal boiling point among the given compounds.

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Answer:

He or She used the wrong table of bond energies

Explanation:

We know that we obtain the energy of a reaction also known as the enthalpy of reaction from the formula; ΔHo(reaction) = sum of the bond energies of bonds being broken - sum of the bond energies of the bonds being formed.

Combustion is an exothermic reaction for which the value of ΔH is expected to the negative. If ΔH is not negative, then the calculation was not properly done and the wrong values of bond energy were probably used.

Answer:

He or she may have subtracted the bond energies for the reactants from the products.

Explanation:

Answer:

See explanation

Explanation:

Number of moles of Cl2 = 0.71g/71g/mol = 0.01 moles

Number of moles = 1.0 g/38g/mol = 0.02 moles

Total = 0.01 + 0.02 = 0.03 moles

From the ideal gas equation;

PV=nRT

P=?

V= 258 ml

n= 0.03 moles

T= 296 K

P= nRT/ V

P= 0.03 × 0.082 × 296/258

P= 0.003 atm

Partial pressure Cl2 = 0.01/0.03 × 0.003 atm = 0.001 atm

Partial pressure = F2 = 0.02/0.03 × 0.003atm = 0.002 atm

Answer:

It would cause scattering of light and absorbance measurement is going to be reported as too large

Explanation:

The curvette was not inserted correctly into the spectrometer. The effect that this would have on measured absorbance is that it would cause scattering of light.

Failing to line the curvette correctly would cause light to scatter, the light reaching the photodetector would be less. This less light would then be interpreted as more light being absorbed. This would end up making the absorbance value to be read as too large.

Answer:

136.63 °C

Explanation:

ΔTb=Tb solution - Tb pure

Where; Tb pure = 133.60°C

molar mass of solute = 121.14 g/mol

number of moles of solute; 52.2g/121.14 g/mol = 0.431 moles

molality = 0.431 moles/350 * 10^-3 = 1.23 molal

Then;

ΔTb = Kb * m * i

Kb = 2.46°C kg mol^-1

m = 1.23 molal

i = 1

ΔTb = 2.46 * 1.23 * 1

ΔTb = 3.03 °C

Hence;

Tb solution = ΔTb + Tb pure

Tb solution = 3.03 °C + 133.60°C

Tb solution = 136.63 °C

Answer:

that they all dissolved went on watef

Answer: [tex]\Delta H^{0} = -879.15 kJ/mol[/tex]

Explanation: Heats of formation is the amount of heat necessary to create 1 mol of a compound from its molecular constituents. The basic conditions the substance is formed is at standard conditions: 1 atm and 25°C. Each compound has its own heat of formation per mol of compound (kJ/mol), but to an element is assigned a value of zero.

Standard Enthalpy Change is defined as the heat absorbed or released when a reaction takes place. It can be positive or negative, which means reaction is endothermic or exothermic, respectively.

Enthalpy change is calculated as the difference between the sum of heat formation of products and the sum of heat formation of the reactants:

[tex]\Delta H^{0}=\Sigma H^{0}_{f}_{(products)}-\Sigma H^{0}_{f}_{(reactants)}[/tex]

For the reaction

   2NH₃   +      3N₂O   →      4N₂    +     3H₂O

2(-46.2)   +     3(82.05)      4(0)    +    3(-241.8)

[tex]\Delta H^{0}=3(-241.8)-[ 2(-46.2)+3(82.05)][/tex]

[tex]\Delta H^{0}=-725.4-153.75[/tex]

[tex]\Delta H^{0}=-879.15[/tex]

The standard enthalpy change for the reaction is [tex]\Delta H^{0}=-879.15[/tex] kJ

Answer:

b. Heat flows from the surroundings to the system and the temperature of the water decreases.

Explanation:

The laws of thermodynamics lets us know that energy is neither created nor destroyed but can be converted from one form to another. Also, energy transfer does accompany chemical reactions in the form of heat.

For an endothermic reaction, heat is absorbed by the system from the surroundings. This leads to a drop in the temperature of the surroundings as energy is removed.

This implies that the water temperature decreases.

Answer: [tex]KF[/tex] > [tex]CH_2O[/tex] > [tex]C_2H_2[/tex]

Explanation:

The order of boiling point depends upon the type of interactions present between the molecules.

Potassium fluoride (KF) is an ionic compound and the opposite ions are held together by strong electrostatic forces.

[tex]C_2H_2[/tex] is a covalent compound and the molecules are held together by weak van der Waals' forces.

Formaldehyde is a polar compound due to presence of polar carbonyl group. Hence dipole-dipole force is present between formaldehyde molecules.

Thus the decreasing order of boiling point is:

[tex]KF[/tex] > [tex]CH_2O[/tex] > [tex]C_2H_2[/tex]