according to the periodic table, which two elements have an atomic mass less than twice their atomic number?

Answer:

Solution given:

2 Al + 3 H2SO4 – Al2(SO4)3 + 3H2

2mole +3mole. --- 1 mole + 3 mole

27×2g. +3×98g-------- 342,g. + 6g

we have

2 mole of Al gives. 6g of h2

5 moles of Al gives 6/2×5=15g of hydrogen

15 g is your answer

Answer:

D. Black Holes

Explanation:

Black holes are large objects that form dense gravity wells in space. Their gravitational pull is so strong that even light cannot escape it. 

Large objects that form dense gravity wells in space are stars and blackholes. The correct answer is option B and D.

Gravity: it is referred to as force of attraction experienced by a body having mass, towards the center of Earth.

Both stars and black holes are massive objects that exert a significant gravitational force due to their mass. They create what is known as a gravity well, which is a region of space where the gravitational pull is strong enough to affect the motion of nearby objects.

On the other hand, Galaxies and nebulae, are not individual objects with sufficient mass to form dense gravity wells. Galaxies consist of a collection of stars, gas, and dust, and while they have a collective gravitational influence, it is not concentrated in a single massive object like a star or black hole. Whereas, Nebulae are interstellar clouds of gas and dust, which do not possess the mass required to create significant gravity wells.

Therefore, the correct options from the given list that form dense gravity wells in space are B. Star and D. Black holes.

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Answer:

Commensalism is a symbiotic relationship in which one species benefits while the other species is not affected. One species typically uses the other for a purpose other than food.

Answer:

dbdbdbdjdbdjdb zbdjdjdjdirfjfjrjdudhdhdhd

Answer:

triangles

Explanation:

Answer:

67.3 kPa

Explanation:

We're focusing on pressure and volume of gases, so we can use our ideal gas law formula PV=nRT. Everything is constant except pressure and volume, but the values change when moving from city 1 to city 2, so we can say PV city 1= PV city 2.

We can simplify our formula to be P1V1=P2V2. This is specifically Boyle's Law, where if pressure increases (from city 1 to city 2) then volume decreases, thus we can say pressure and volume have an inverse/opposite relationship.

This is an important formula to understand, you can easily memorize it by referring to PV=nRT.

Let's plug in the values we know.

P1V1=P2V2

(101)(6) = (9)(V2)

Now let's solve for V2.

[tex]\frac{101 x 6}{9}[/tex]  = V2

[tex]\frac{606}{9}[/tex] = V2

67.3 kPa = V2

Answer:

Mechanical Sound Waves

A mechanical wave is a wave that depends on the oscillation of matter, meaning that it transfers energy through a medium to propagate. These waves require an initial energy input that then travels through the medium until the initial energy is effectively transferred. Examples of mechanical waves in nature include water waves, sound waves, seismic waves and internal water waves, which occur due to density differences in a body of water. There are three types of mechanical waves: transverse waves, longitudinal waves, and surface waves.

Why is sound a mechanical wave? Sound waves move through air by displacing air particles in a chain reaction. As one particle is displaced from its equilibrium position, it pushes or pulls on neighboring molecules, causing them to be displaced from their equilibrium. As particles continue to displace one another with mechanical vibrations, the disturbance is transported throughout the medium. These particle-to-particle, mechanical vibrations of sound conductance qualify sound waves as mechanical waves. Sound energy, or energy associated with the vibrations created by a vibrating source, requires a medium to travel, which makes sound energy a mechanical wave.

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Answer:

35.8 g

Explanation:

Step 1: Given data

Mass of water: 63.5 g

Step 2: Calculate how many grams of KCl can be dissolved in 63.5. g of water at 80 °C

Solubility is the maximum amount of solute that can be dissolved in 100 g of solute at a specified temperature. The solubility of KCl at 80 °C is 56.3 g%g, that is, we can dissolve up to 56.3 g of KCl in 100 g of water.

63.5 g Water × 56.3 g KCl/100 g Water = 35.8 g KCl

Answer:

The raindrops of mass 0.050g has 0.0028 moles of water

Answer:

Pull

Explanation:

The higher the effective nuclear charge, the more the nucleus will be gaining protons. This process makes the electrons to be drawn closer to the positive charge of the nucleus.

Thus, it leads to a greater pull exerted by the nucleus on the added electrons.

Explanation:

Because a large amount of energy is required to break the strong inter-ionic attraction.

CaS => Ca2+ & S2-

Explanation:

The higher the wavelength, the lower its frequency and energy

Answer:

As frequency increases wavelength decreases in size

Explanation:

The wavelength of the wave is inversely proportional to the frequency of the wave as the speed of the wave remains constant.

                                v = fλ ( v - speed, f - frequency,  -wavelength)

                                 [tex]\frac{v}{\lambda}[/tex] = f

Therefore at constant speed:

                                 f ∝ [tex]\frac{1}{\lambda}[/tex] (inversely proportional)

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Answer:

4.5 × 1015 J

Explanation:

Energy was released through this form of mass.

The energy released if a sample loses 0.05 kg mass through

radioactive decay is  45 ×10¹⁴ J.

The ability to do work is called energy.

The Einstein's formula can be used to find the energy released. Energy is the product of mass  and  the velocity of light in a vacuum squared.

Given that the mass is 0.05 kg and speed of light in vacuum is 3×10⁸ m/s.

E = 0.05 × (3×10⁸)²

E = 45 ×10¹⁴ J

The energy is released if a sample loses 0.05 kg mass through

radioactive decay is 45 ×10¹⁴ J.

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Answer:

Solid

Explanation:

The reason is because the liquid aspirin has a plastic cover with a liquid inside and it doesn't take long for out stomach acid to dissolve the cover unlike the Solid aspirin where is slowly dissolves.

Answer:

1162m/s is the faster speed

Explanation:

The speed is a physical property defined as the distance travelled of an object in determined amount of time.

A speed of 316m/s means the object is travelling 316 meters per second transcurred.

In the same way, the speed of 1162m/s means the object is travelling 1162m per second.

As the second object is travelling more distance per second than the first,

Explanation:

Sodium Chloride is neutral whereas hydrochloric acid is an acid. 2. Sodium Chloride is solid while hyrdochloric acid is a gas.

Answer:

Explanation:

Equilibrium is achieved in a chemical reaction when there is a steady state with no change in concentrations.

So the answer is "When the concentrations of reactants and products are constant."

Answer:

Explanation:

Increasing the temperature increases reaction rates because of the disproportionately large increase in the number of high energy collisions.

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Answer:

In chemistry, an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding

Answer:

An Ionic compounds are compounds consisting of ions also held together by the attractive forces among the oppositely charged ions.

Explanation:

For example :

NaHCO3, sodium bicarbonate (baking soda; used in cooking)

NaCl, sodium chloride (common/ordinary salt)

Answer:

Have Nice Day

Explanation:

2NaCI is the answer

Respuesta:

1.50 moles

Explicación:

Paso 1: Escribir la ecuación química ajustada para la descomposición del carbonato de calcio

CaCO₃ ⇒ CaO + CO₂

Paso 2: Calcular los moles correspondientes a 150 g de CaCO₃

La masa molar de CaCO₃ es 100.09 g/mol.

150 g × 1 mol/100.09 g = 1.50 mol

Paso 3: Calcular los moles de CO₂ producidos a partir de 1.50 moles de CaCO₃

La relación molar de CaCO₃ a CO₂ es 1:1.

1.50 mol CaCO₃ × 1 mol CO₂/1 mol CaCO₃ = 1.50 mol CO₂

Answer:

4121 years

Explanation:

From;

0.693/t1/2 = 2.303/t log No/N

t1/2= half life of the carbon-14

No= count rate of the living tissue

N= count rate of the sample

t = age of the sample

0.693/5730 =2.303/t log (13.5/8.2)

1.21 * 10^-4 = 2.303/t * 0.2165

1.21 * 10^-4 = 0.4986/t

t = 0.4986/1.21 * 10^-4

t = 4121 years

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Answer:  The bonds that are made and broken in a reaction release energy when forming products that contain less total energy than the reactants.

Explanation:  Elements form bonds with each other when the total energy of the resulting products is less than the starting energy.  The term "energy" refers to the energy of the electrons that are being held in an atom by the nucleus.  Keeping the positively charged nucleus happy means that the electrons are trying to get closer, but they repel each other as they get closer to the nucleus.  This results in orbits, preferred areas around the nucleus where the electrons spend their day in a delicate balance with the nucleus and other electrons.  These orbits offer housing for the electrons that involve discreet energies for the electrons.  When elements react, the resulting bonding pattern often results in an overall reduction in total energy.  The energy reduction results in heat, light, and/or sound.  The release is termed "exothermic."

Answer:

5:2

//answer was too short //

Answer:

The ratio by mass for calcium and oxygen in a calcium oxide is given by 5:2

hope it helps

Answer:

Explanation:

The new pressure can be found by using the formula for Boyle's law which is

[tex]P_1V_1 = P_2V_2[/tex]

Since we're finding the new pressure

[tex]P_2 = \frac{P_1V_1}{V_2} \\[/tex]

We have

[tex]P_2 = \frac{6.4 \times 0.87}{20.5} = \frac{5.568}{20.5} \\ = 0.2716.... \\ \\ = 0.27 \: \: \: atm[/tex]

But

1 atm = 14.7 psi

Then 0.27 atm =

[tex] \frac{14.7 \times 0.27}{1} = 3.969 \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

3.97 psi

Explanation:

Answer:

H2SO4 sulfuric acid 2.75

Explanation:

I hope it will help you