Please answer this question.

Answer:

7.99 moles of boron

Explanation:

Given data:

Number of moles of B = ?

Number of atoms of B = 4.81 × 10²⁴ atom

Solution:

Avogadro number:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.  The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ atoms

4.81 × 10²⁴ atom × 1 mol / 6.022 × 10²³ atoms

0.799 × 10¹ mol

7.99 moles

Answer:

B) fewer in number and less strongly held

Explanation:

If we  look closely at the periodic table from left to right, we will notice that the number of valence electrons increases steadily as we move across the periodic table from left to right.

Metals are mostly at the left hand side of the periodic table while nonmetals are found at the righthand side of the table.

Metals are less electronegative than nonmetals and typically have a lower effective nuclear charge than nonmetals hence the fewer valence electrons of metals are less strongly held(due to less effective nuclear charge) than those of nonmetals.

Answer:

Nuclear Binding Energy (Bond Energy), Higher (Greater)

Explanation:

The energy required to overcome the attraction between two bonded nuclei and their shared electrons is called Nuclear Binding Energy (Bond Energy). This quantity is a measure of bond strength since the stronger the bond, the Higher (Greater) the amount of energy required to break it.

The energy required to overcome the attraction between two bonded nuclei and their shared electrons is called bond energy. This quantity is a measure of bond strength since the stronger the bond, the greater amount of energy required to break it.

I hope this helps!

Answer:

It has 7 electrons in it last shell. it will gain one electron to complete its octet and become Cl-. The ionic bond of chlorine form with potassium is Kcl ( potassium chloride)

To solve such this we must know the concept of ionic reaction. Cl is the element could gain one electron to form an ionic bond with potassium.

Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound.

Potassium will act as cation as K⁺, chlorine has 7 electrons in it last shell, it can gain one electron to complete its octet and become Cl⁻. The ionic compound of Cl with K is KCl.

Phosphorus has 5 electrons in its last shell it so, it needs 3 more electron to get stable .Sulphur has 6 electron, it needs 2 electrons to get stable. Argon is already stable as it has 8 electrons in its last shell so, it will not gain or loose any electrons.

Therefore, Cl is the element could gain one electron to form an ionic bond with potassium.

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Answer:

El gas se calentó a 35°C

Explanation:

Para resolver este problema es necesario aplicar la Ley de Gay Lussac donde en una situación en la que un gas no modifica su volumen, su temperatura será directamente proporcional a la presión.

Podemos pensar que se describe desde la Ley de Gases Ideales donde:

P . V = n . R . T

para la situacion 1

y P . V = n . R . T para la situacion 2

Como V, n y R son constantes:

P₁ / T₁ = P₂ / T₂

250000 Pa / 25°C = 350000 Pa / T₂

T₂ = 350000 Pa . 25°C / 250000 Pa → 35°C

Answer:

Magnetic: Iron and nickel

Nonmagnetic: Rubber, feathers and/or leather

Explanation:

Hope this helps!

Answer:

false it is a chemical change

Answer:

a

Explanation:

Explanation:

On a hot day, the speed at which we perceived the smell of the perfume will be much faster due to the increase in kinetic energy of the perfume molecules.

Based on the kinetic molecular theory of gases, the average motion of particles increases as their thermal energy increases. On a hot day, the heat causes an increase in the average kinetic energy of the particles and the perfume molecules moves faster.

On a cold day, the molecules are slower and the rate at which we perceive the perfume smell is very slow. The particles will diffuse less faster and this is due to the low average kinetic energy they possess.

Answer:

This law established a relationship between atomic number of element and frequency of X-rays of that atom. According to this law, the square root of frequency of X-rays imparted by elements is directly proportional to the atomic number of that element.

Answer:

Q = 9460 Kj

Explanation:

Given data:

Mass of copper = 2kg

Latent heat of vaporization = 4730 Kj/Kg

Energy required to vaporize 2kg copper = ?

Solution:

Equation

Q= mLvap

It is given that heat required to vaporize the one kilogram copper is 4730 Kj thus, for 2 kg

by putting values,

Q= 2kg ×  4730 Kj/Kg

Q = 9460 Kj

Answer:

The lowest possible melting point for engine coolant is -12.8°C

Explanation:

This is about colligative property about freezing point depression.

We think the data 30% as a %m/m. It means that 30 g of ethylene glycol are contained in 100 g of solution. Therefore, we have 70 g of solvent.

Formula for freezing point depression is:

ΔT = Kf . m . i

Where  ΔT = Freezing T° of pure solvent - Freezing T° of solution.

Freezing T° of solvent = 0° (We talk about water)

Let's determine m (molality, moles of solute in 1kg of solvent)

70 g = 0.070 kg

30 g . 1 mol / 62.07 g = 0.483 moles

0.483 mol / 0.070 kg = 6.90 m

We replace data in formula:

0° - Freezing T° of solution = 1.86 °C/m . 6.90m . 1

As ethylene glycol is a nonelectrolyte, i = 1

Freezing T° of solution =  - 12.8°C

Answer:

The columns of the periodic table are called groups. Members of the same group in the table have the same number of electrons in the outermost shells of their atoms and form bonds of the same type. The horizontal rows are called periods.

Answer:

V₂ =  1.92 L

Explanation:

Given data:

Initial volume = 0.500 L

Initial pressure =2911 mmHg (2911/760 = 3.83 atm)

Initial temperature = 0 °C (0 +273 = 273 K)

Final temperature = 273 K

Final volume = ?

Final pressure = 1 atm

Solution:

Formula:  

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

by putting values,

V₂ = P₁V₁ T₂/ T₁ P₂  

V₂ = 3.83 atm × 0.500 L × 273 K / 273 K × 1 atm

V₂ = 522.795 atm .L. K / 273 K.atm

V₂ =  1.92 L

Explanation:

it's answer is false

hope it helps you

Answer:

Explanation:

Mole ratios are used as conversion factors between products and reactants in stoichiometry calculations.. For example, in the reaction . 2H₂(g) + O₂(g) → 2H₂O(g) The mole ratio between O₂ and H₂O is #(1 mol O₂)/(2 mol H₂O)#.

To calculate the atoms of an element in a given molecule, we need to multiply stoichiometry by the number that is written on the foot of that element. The mole ratio between HCl and H20 is 1:1.

Balanced equation is the one in which the total number of atoms of a species on reactant side is equal to the total number of atoms on product side. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, displacement reaction.

Physical state should be written in brackets. s means solid, l means liquid, g means gas. Mole ratios are used as conversion factors between products and reactants in stoichiometry calculations. The mole ratio between HCl and H20 is 1:1.

Therefore, the correct option is option A.

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Answer:

See explanation

Explanation:

According to Newton's second law, the rate of change of momentum is proportional to the impressed force.

Mathematically;

Ft = mv - mu

Where;

F = Force

t = time

m= mass

v = final velocity

u = initial velocity

Since the mass is the same, the equation reduces to;

Ft = m(v-u)

So

F=  m(v-u)/t

but

(v-u)/t = acceleration (a)

F = ma

a = F/m

Since the mass is the same because Sarah is the same size as i am but she pulls with a greater force, it follows that i will be the one in the wagon when the wagon has the greatest acceleration because the force that Sarah applies when pulling me is greater than the force i will apply when pulling her.

The mass of Copper deposited at the cathode : 0.296 g

Given

time = t = 10 min=600 s

current = i = 1.5 A

F = 96500 C

charge Cu=+2

Required

The mass of Copper

Solution

Faraday's Law

[tex]\tt W=\dfrac{e.i.t}{96500}[/tex]

e = Ar/valence(valence Cu=2, Ar=63.5 g/mol)

Input the value :

[tex]\tt W=\dfrac{63.5/2\times 1.5\times 600}{96500}\\\\W=0.296~g[/tex]

Answer:

young soil has less organic materiel that old

Explanation:

Answer:

2 and 3 only

Explanation:

The formular for the compound; Silicon(IV)oxide is SO2

1. Silicon atoms form four single bonds in silicon(IV) oxide.

This statement is wrong because the silicon is doubly bonded to two oxygen atoms.

2. Oxygen atoms form two double bonds in silicon(IV) oxide.

This statement is correct.

3. Silicon(IV) oxide has a high melting point.

This statement is correct Due to it's macromolecular structure, it is able to form thousands of covalent bonds between it's sulphur and oxygen sub units.

4. Silicon(IV) oxide contains one silicon atom and four oxygen atoms.

This statement is wrong as silicon(iv) oxide contains only two oxygen atoms.

Answer:

the best answer would be A

Explanation:

cause it contains a red colored compound.

Answer:

2.64 ×[tex]10^{-26}[/tex] J

Explanation:

I think you should mark it a physics question instead but anyway.

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The Planck equation should be applied:

E = hv , while E is energy of proton; h is Planck constant; and v is frequency.

E = 6.6 × [tex]10^{-34}[/tex] × 4 × [tex]10^{7}[/tex]

  = 6.6 × 4 × [tex]10^{-27}[/tex]

  = 2.64 ×[tex]10^{-26}[/tex] J

Answer:

Sr or Strontium

Explanation:

sr: strontium has atomic radius of 255pm

cu: copper has an atomic radius of 128pm

they teach you in chem how to do it based off the chart but I don't remember that method

Answer:

D.When the boiling points of the components are different

Explanation:

I believe the formal name for this procedure is actually distillation.

Answer:

subsystems.

Explanation:

A self-contained system within a larger system. system. A group of interacting or interdependent elements forming a complex whole, as in all the factors or variables in an environment or all the variables that might affect a science experiment.

Volumes of ethanol and water are in the solution : 30 mL and 70 ml

The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight/volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.

Percent Volume (% v/v) : volume (ml) of solute/100 ml of solution ⇒ ratio of volume of the solute to total volume of the solution

[tex]\tt \%solute=\dfrac{solute~volume}{solution~volume}\times 100\%[/tex].

30% ethanol ⇒30% etanol, 70% water

In 100 mL solution :

[tex]\tt Ethanol=30\%\times 100~mL=30~mL\\\\Water=70\%\times 100~mL=70~ml[/tex]

Answer: C.  

Explanation: These offspring inherited a DNA sequence coding for white flowers from each parent plant.

:)

Answer:

BLOOD - the definition of blood is the fluid carries oxygen

Explanation:

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