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Q1: Give the letter of a substance that is a solid at 20 °C
Q2: Give the letter of a substance that is a liquid at 50 °C

Answer:

Minimum 2. ( Thats how I do, and till now there is no probs)

Thank You'

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Answer:

For a good consert mix aggregate needed to the clean hard strong partical free of absorb chemicals or coating clay and other fine materials

Answer: true

Asexual reproduction is the process by which an organism is produced from a single parent cell. There are four major forms of asexual reproduction - budding, binary fission, regeneration and parthenogenesis. ... Regeneration is a type of asexual reproduction in which the organism is capable of regrowing certain body parts.

Explanation:

id k what u r talking abt but hope this helps

The addition of any non-volatile solutes will elevate the boiling point of the solution. The change in boiling point of water by the addition of 2.10 of barium chloride is 0.0028 ° C. Hence, option A is correct.

Boiling point of a substance is the temperature at which it changes from liquid to vapour where the two states are in equilibrium. Boiling point of a substance depends on the bond type, molecular mass and purity of it.

The change or elevation of boiling point of a solution can be determined from its molality m and elevation constant Kb and the Van't Hoff factor i as follows:

ΔT = i Kb m.

Molality of the solution is the no.of moles divided by the mass of solvent in kilogram. Given the mass of barium chloride is 2.10 g and its molar mass is 208.23 g . The no.of moles of solute is 2.10/208.23 g = 0.0100.

Molality of the solution can be calculated as follows:

Molality m = 0.0100 / 5.50 Kg

                 = 0.0018 mol/kg.

Now, the  ΔT s calculated from these values. Provided Kb of water is 0.51 ° C /mol and i = 3.

ΔT  = 0.0018 mol/kg × 0.51 × 3

       = 0.0028 ° C.

Therefore, water will boil at 100.0028 ° C. Hence, option A is correct.

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Answer:

All substances can be characterized by their unique sets of physical and chemical properties. Properties that can be determined without changing the composition of a substance are referred to as physical properties. Characteristics such as melting point, boiling point, density, solubility, color, odor, etc.

Answer:

2.95 * 10^23 atoms

Explanation:

The number of atoms in a mole is always equal to Avogadro's constant, which is 6.02214076×10²³ mol⁻¹.

To find the number of atoms in 0.490 moles of barium, multiply it with Avogadro's constant:

0.490 mol * 6.02214076×10²³ mol⁻¹ ≈ 2.9508 * 10^23

Convert to SigFigs (if necessary):

2.95 * 10^23

Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom.

The equation Fe + CuSO₄ → Cu + FeSO₄ illustrates the single displacement reaction. Hence Option (D) is the correct answer.

A single replacement reaction, sometimes called a single displacement reaction, is a reaction in which one element is substituted for another element in a compound.

The starting materials are always pure elements, such as a pure zinc metal, iron or hydrogen gas, plus an aqueous compound.

Therefore, the equation Fe + CuSO₄ → Cu + FeSO₄ illustrates the single displacement reaction. Hence Option (D) is the correct answer.

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Answer:c

Explanation: it’s c

Answer:

MgCO3 + 2 NaNO3

Explanation:

Answer:

Explanation:

a) photosynthesis

b) Substances used: water, sun, gas and nutrients. Products: glucose and flowers

c) there will be no sunlight or no open environment

Answer:

The final temperature aluminium-water system is 24° C

Explanation:

Heat energy, H = mcθ

Where m is mass of substance, c is specific heat capacity, θ is temperature difference

Using the principle, Heat lost = Heat gained

Let the final temperature of the aluminium-water system be Tfinal

Heat lost by aluminium, H₁ = -m₁c₁(Tfinal - 40)

Heat gained by water, H₂ = m₂c₂(Tfinal -21)

Heat lost by aluminium, H = -[30 × 0.21 × (Tfinal - 40)]

H₁ = -6.3Tfinal + 252

Heat gained by water, H₂ = 50 × 1.0 × (Tfinal - 21)

H₂ = 5Tfinal - 21

Equating H₁ and H₂

-6.3Tfinal + 252 = 5 Tfinal - 21

5Tfinal + 6.3Ffinal = 252 + 21

11.3 Tfinal = 273

Tfinal = 273/11.3

Tfinal = 24° C

Therefore, the final temperature aluminium-water system is 24° C

Answer: A pattern of same atomic orbitals can be seen about elements in the same period with respect to electron structures.

Explanation:

The horizontal rows in a period table are called periods.

Elements present in the same period will have same atomic orbitals.

For example, electronic distribution of Na is 2, 8, 1 and it is a third period element.

Similarly, electronic distribution of Cl is 2, 8, 7 and it is also a third period element.

Hence, both Na and Cl will have K, L, M shells, that is, they have three atomic orbitals.

Thus, we can conclude that a pattern of same atomic orbitals can be seen about elements in the same period with respect to electron structures.

Answer:

The more polar the molecules, the stronger the force. The more hydrogen in the molecule, the stronger the force.

Explanation:

I hope this helps and please ask if you need further help!

The option that isn't a reason why the actual yield is less than theoretical yield is B. conservation of mass.

It should be noted that the formula for the percent yield is given as:

= Actual yield / Theoretical Yield × 100

Actual yield can be less than theoretical yield due to the presence of impure reactants ,competing side reactions, and loss of product during purification.

In conclusion, the correct option is B.

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Answer: The molality of [tex]NaC_2H_3O_2[/tex] solution is 0.782 m

Explanation:

Molality is defined as the amount of solute expressed in the number of moles present per kilogram of solvent. The units of molarity are mol/kg. The formula used to calculate molality:

[tex]\text{Molality of solution}=\frac{\text{Moles of solute}}{\text{Mass of solvent (in kg)}}[/tex] .....(1)

Given values:

Moles of [tex]NaC_2H_3O_2[/tex] = 0.395 mol

Mass of solvent (water) = 0.505 kg

Putting values in equation 1, we get:

[tex]\text{Molality of }NaC_2H_3O_2=\frac{0.395mol}{0.505kg}\\\\\text{Molality of }NaC_2H_3O_2=0.782m[/tex]

Hence, the molality of [tex]NaC_2H_3O_2[/tex] solution is 0.782 m

Answer:

false

Explanation:

edge 2022

Answer:

Some of the common impacts of earthquakes include structural damage to buildings, fires, damage to bridges and highways, initiation of slope failures, liquefaction, and tsunami.

Answer:

The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons.

Based on the wave model of light, physicists predicted that increasing light amplitude would increase the kinetic energy of emitted photoelectrons, while increasing the frequency would increase measured current.

Answer:

the number of electrons in a particular shell is given by the formula 2n^2 . However an electron when gets very exicited loose energy in the forms of radiation and comes in high energy level shell.

Answer:

C. Compression

Explanation:

I'm pretty sure it's compression

Answer:

D. Something that splits up light into different colors

Explanation:

A prism separates light into various different colors. Thus, D is correct. :)

Answer:

When heated, oxygen reacts with copper to form copper oxide. If this reaction occurs in a sealed container, will the mass of the container and everything in it increase, decrease, or stay the same and why? The mass will increase because a new kind of molecule is formed.

Explanation:

As above, carbonates decompose upon heating to give the metal oxide and carbon dioxide. The mass is lost as carbon dioxide.

To solve this we must be knowing each and every concept related to mass. Therefore, Carbon dioxide is released as the mass is depleted when carbonates are heated.

Mass defines the quantity of a substance. It is measured in gram or kilogram. Average mass is the mass of atoms of an element that are isotopes.

When copper was heated in the air, the resulting solid product has a larger mass than the initial copper. When calcium carbonate was heated in air, the resulting solid product has much less mass than the initial calcium carbonate. When carbonates are heated, they breakdown into metal oxides and carbon dioxide. Carbon dioxide is released as the mass is depleted.

Therefore, Carbon dioxide is released as the mass is depleted.

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Answer:

Atoms are single neutral particles. Molecules are neutral particles made of two or more atoms bonded together.

Explanation:

its on safari ??????????

Chart for question attached

Answer:

Joshua

Explanation:

By cost-effective here, we mean the contractor that does the job best at the shortest time and lowest money cost. To get this, we calculate total cost for each contractor and then consider time for completion of the job:

Joshua charges $25 per hour for 5 hrs

Carmen charges $20 per hour for 7 hrs

Dante charges $30 per hour for 6 hrs

Alicia charges $20 per hour for 8 hrs

Joshua's cost= $25×5=$125 in 5 hours

Carmen's cost = $20×7= $140 in 7 hours

Dante's cost= $30×6=$180 in 6 hours

Alicia's cost= $20×8= $160 in 8 hours

From the above we can see that Joshua is the most cost-effective contractor given that he completes the job in less time and with less money.

Answer:

He supported the ideology of Marxism.

He opposed the tsar and was exiled.

He led the Bolsheviks.

Explanation:

Lenin was Russian Revolution political theorist. He served as first founding head of government of Soviet Russia. He supported the ideology of Marxism and opposed Tsar.

Answer:

parietal pleura

Explanation:

The pleurae, which are serous membranes, divide the thoracic cavity's wall from the lungs. The parietal pleura covers the interior of the thorax, mediastinum, and diaphragm, while the visceral pleura covers the surface of the lungs.

The perianal pleura, the outer layer, is attached to the chest wall. The lungs, mediastinum's neurovascular structures, and bronchi are all covered by the inner layer (visceral pleura).

The pleura's role in breathing is to enable the lungs to expand and collapse as efficiently as possible.

The parietal and visceral pleura can move over one another without rubbing against one another thanks to the pleural fluid's lubricating properties. The pleural layers themselves produce this fluid.

Therefore, parietal pleura, which surround the lungs in thoracic cavity.

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Answer:

PCl5 <-> PCl3 + Cl2

PCl5 decomposes into PCl3 and Cl2 according to the equation above. A pure sample of Pcl5 is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl5 is 1.00 atm. The temperature is held constant until the PCl5 reaches equilibrium with its decomposition products. The figures below show the initial and equilibrium conditions of the system.

As the reaction progresses toward equilibrium, the rate of the forward reaction

A) increases until it becomes the same as the reverse reaction rate at equilibrium

B) stays constant before and after equilibrium is reached

C) decreases to become a constant nonzero rate at equilibrium

D) decreases to become zero at equilibrium

Explanation:

At equilibrium, both forward and backward reactions take place with constant speed.

The reaction will never cease.

Due to this reason chemical equilibrium is called dynamic in nature.

At equilibrium:

the rate of forward reaction = rate of backward reaction

As the reaction progresses toward equilibrium, the rate of the forward reaction decreases to become a constant nonzero rate at equilibrium.

Answer is option C).

When a system is in a state of chemical equilibrium, neither the reactant concentration nor the product concentration changes over time, nor does the system exhibit any further changes in its attributes. Here the correct option is C.

The system reaches a condition of chemical equilibrium when the rate of the forward reaction equals the rate of the reverse reaction. The system is considered to be in a state of dynamic equilibrium when the concentrations of the reactants and products do not change further as a result of the equal rates of the forward and reverse processes.

Equilibrium is impacted by a number of variables, including temperature, pressure, and the system's concentration. Here at equilibrium the rate of the forward reaction decreases to become a constant nonzero rate at equilibrium.

Thus the correct option is C.

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Answer:

La piel.

Explanation:

La piel es el órgano que forma el límite del cuerpo con el mundo exterior. La piel sirve para varios propósitos. Protege al cuerpo de influencias externas como el calor, el frío, la radiación o las bacterias y ayuda a mantener un ambiente interno estable. La piel está fuertemente atada a los huesos y tejidos. Por lo general, la piel alberga más de 100 especies bacterianas diferentes y algunas investigaciones sugieren que la mayoría de estas bacterias son beneficiosas y aumentan la probabilidad de que se evite la infestación de parásitos.