Câu 36: _VD _Hình lập phương có thể tích là 1253 thì diện tích đáy là:

A. cm2 B. 5cm2 C. 25cm2 D. 52cm2

Answer:

Explanation:Visit this site for any assignments assistance

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Answer:

A chemical reaction that has a positive ΔH is said to be endothermic , while a chemical reaction that has a negative ΔH is said to be exothermic . What does it mean if the ΔH of a process is positive? It means that the system in which the chemical reaction is occurring is gaining energy.

Answer:

82 °C

Explanation:

Let the specific heat capacity of the coffee be that of water which is 4.2 J/g °C.

Now, at the final temperature, heat gained by Aluminum spoon ,Q equals heat lost by coffee, Q'.

Q = -Q'

Q = m₁c₁(T₂ - T₁) where m₁ = mass of aluminum spoon = 45 g, c₁ = specific heat of aluminum = 0.88 J/g °C, T₁ = initial temperature of aluminum spoon = 24 °C and T₂ = final temperature of aluminum spoon.

Q' = m₂c₂(T₂ - T₃) where m₂ = mass of coffee = 180 g, c₂ = specific heat of coffee = 4.2 J/g °C, T₃ = initial temperature of coffee = 85 °C and T₂ = final temperature of coffee.

So, Q = -Q'

m₁c₁(T₂ - T₁) = -m₂c₂(T₂ - T₃)

Making T₂ subject of the formula, we have

m₁c₁T₂ - m₁c₁T₁ = -m₂c₂T₂ + m₂c₂T₃

m₁c₁T₂ + m₂c₂T₂ =  m₂c₂T₃ + m₁c₁T₁

(m₁c₁ + m₂c₂)T₂ =  m₂c₂T₃ + m₁c₁T₁

T₂ =  (m₂c₂T₃ + m₁c₁T₁)/(m₁c₁ + m₂c₂)

substituting the values of the variables into the equation, we have

T₂ =  (180 g × 4.2 J/g °C × 85 °C + 45 g × 0.88 J/g °C × 24 °C )/(45 g × 0.88 J/g °C  + 180 g × 4.2 J/g °C)

T₂ =  (64260 J + 950.4 J)/(39.6 J/°C  + 756 J/°C)

T₂ =  65210.4 J/795.6 J/°C

T₂ =  81.96 °C

T₂ ≅  82 °C

Answer:

Explanation:

pretty sure its mixure.

Answer:

Model

Explanation:

A model of anything is something you make to represent it in it's physical world form

The heat of hydration is defined as the heat absorbed or evolved when one mole of a substance undergoes hydration. The heat of solution is the enthalpy change associated with he dissolution of a solute. The lattice energy is the heat. Lattice energy is the energy released when the components of the lattice are brought together from infinity.

Hence the heat of solution for LiF → Li^+ + F- is -1966  kJ/mol

Given that;

Heat of hydration = ΔH solution – ΔH lattice energy

Where,

ΔH solution  = Heat of the solution

ΔH lattice energy = Lattice energy of the solution

The heat of solution or enthalpy of dissolution is defined as the enthalpy change associated with the dissolution of a solute in a solvent

From the formula above;

ΔH solution = Heat of hydration + ΔH lattice energy

Heat of hydration = [(-431) + (-499)] = -930 kJ/mol

ΔH solution = (-930) + (-1,036) = -1966  kJ/mol

Hence the heat of solution for LiF → Li^+ + F- is -1966  kJ/mol

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Answer:

15.3g

Explanation:

C6H12O6 → 2C2H5OH + 2CO2

1 mol C6H12O6 = 180g

1 mol CH3-CH2-OH = 46g

From 180g glucose ethanol can get = 92g

30g glucose ethanol gives us = (92*30)/180 = 15.33g

Answer:

the answer is 47.9 and ik because I just had that question

The empirical formula of the compound is O₄Pb₃.

An Empirical system is the chemical system of a compound that offers the proportions of the elements gifted within the compound however not the real numbers or arrangement of atoms. This would be the lowest complete variety ratio of the elements within the compound.

Amount of lead (Pb) = 90.6%

⇒and amount of oxygen = 9.4%

taking the whole number ratio

o = 4

Pb = 3

∴ ⇒O: Pb=4:3

O4Pb3 answer.

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Answer:

The answer is "670.176 km".

Explanation:

Volume of the occupies of one  M & M= 0.5 \ cm^3\\\\

M&M 1 mole[tex]= 6.02 \times 10^{23}\\\\[/tex]

Calculating volume of M& M mole[tex]= 0.5 \ cm^3 \times 6.02 \times 10^{23}=3.01 \times 10^{23}\ cm^3\\\\[/tex]

Calculating the cube mole[tex]L^3= 3.01 \times 10^{23}\ cm^3\\\\[/tex]

[tex]L=6.70176 \times 10^{7}\ cm\\\\[/tex]

   [tex]=6.70176 \times 10^{7}\ cm \times \frac{1\ m}{100\ cm}\\\\=670176\ m\\\\=670.176 \ km[/tex]

Therefore 18 tractor trailers wouldn't be sufficient.

Answer:

Answer:

B. Lithium (Li) and iodine (1)

Explanation:

Ionic bond is a type of chemical bond that is formed between a metallic element and a non metallic element. The positive charge of the metallic ion is attracted to the negative charge of the non metallic ion to form an ionic bond.

According to the options given in this question, lithium and iodine will form an IONIC bond because lithium is a cation (+ve ion) while iodine is an anion (-ve).

Answer:

1 Anomalous Pairs. The rest of the  pairs of elements don't follow the follow Mendeleev's Principles . they are :

2Grouping of chemically dissimilar elements.  

3Position of Isotopes.  

4Electronic arrangement.  

5Separation of chemically similar elements.  

6The position of hydrogen.

Answer:

0⁰c , 5 mmHg

Explanation:

Because at this temperature we all know water can be in state of both solid and liquid and when pressure is decreased it can be in form of gas too

Answer:

12 g

Explanation:

From the question given above, the following data were:

Number of atoms = 6.02×10²³ atoms

Mass of ₆C¹² =?

From Avogadro's hypothesis,

1 mole of any substance contains 6.02×10²³ atoms. This implies that 1 mole of ₆C¹² also contains 6.02×10²³ atoms i.e

1 mole of ₆C¹² = 6.02×10²³ atoms

Recall

From the period,

1 mole of ₆C¹² = 12 g

Thus,

12 g of ₆C¹² = 6.02×10²³ atoms

Therefore, 12 g of ₆C¹² contains 6.02×10²³ atoms

C. NaOH

C. Cu (OH)

A. HCl

Answer:

Some examples of solutions are salt water, rubbing alcohol, and sugar dissolved in water. ... In our example of salt water, the solute is the salt. Solvent: this is the substance that makes up the majority of the solution. This is the part where the solute is dissolved.

Explanation:

I hope they should be right answer

Answer:

Los alimentos para evitar la fatiga durante una carrera son alimentos bajos en grasas y altos en carbohidratos, así como alimentos bajos en fibra como pan, mantequilla de maní, plátano, jugo de frutas sin pulpa, y beber hasta aproximadamente 600 ml de líquido aproximadamente 3 horas. antes de la carrera

La comida para comer unos días antes de la carrera incluye carnes magras, arroz, pasta y verduras con contenido de almidón.

Los alimentos que se deben evitar incluyen carne roja, alimentos con alto contenido de grasas saturadas, alimentos fritos, pasteles y salchichas.

Explanation:

Answer:

D

Explanation:

Answer:

solubility of salt at 10 degree Celsius is 20 how does it what does it means what happens if the temperature of saturated solution is increased

Explanation:

solubility of salt at 10 degree Celsius is 20 how does it what does it means what happens if the temperature of saturated solution is increased

A. Coal

Others are animal remains

The fossil fuel which is the remains of ancient plants is: A. Coal.

Non-renewable energy can be defined as a type of energy that is mainly generated through artificial sources or from the remains of ancient plants.

Hence, a non-renewable energy cannot be replenished or renewed like the renewable energy sources.

Basically, some examples of a non-renewable energy include:

Coal deposits are typically petrified peat swamps and peat is generated from decaying plants.

Also, coal has been discovered to be a fossil fuel that contain the remains of ancient plants, based on radioactive dating.

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Explanation:

an acid will give away a proton and become a conjugate base.

A base will accept a proton and become a conjugate acid.

The highest energy sublevel of argon will be p.

Argon has an atomic number of 18.

Thus, the electron configuration of argon will be [tex]1s^2, 2 s^2, 2 p^6, 3 s^2, 3 p^6[/tex]

The ascending order of energy for the sublevel orbitals is s, p, d, and f.

Therefore, the highest energy sublevel of argon is p.

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The highest energy sublevel in the element argon is p.

The periodic table is an arrangement of atoms according to their order of increasing atomic numbers. Now we know that there are 18 groups in the periodic table and argon belongs to group 18.

The electron configuration of argon is; 1s2 2s2 2p6 3s2 3p6. Thus, the highest energy sublevel in the element argon is p.

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Answer:

4i[tex]\sqrt{5}[/tex]

Explanation:

[tex]i^{2}[/tex]= -1

Teniendo en cuenta que la molaridad es el número de moles de soluto que están disueltos en un determinado volumen, la molaridad de la disolución de HNO₃ es 14.67 [tex]\frac{mol}{L}[/tex].

El porcentaje en masa o en peso de una disolución es el número de gramos de soluto que hay por cada 100 gramos de disolución.

Entonces una pureza de 65% indica que hay 70 g de HNO₃ puro por cada 100 g de HNO₃ impuro.

Por otro lado, la densidad es la relación entre el peso o masa de una sustancia y el volumen que ocupa esa misma sustancia.

Entonces, si la disolución de HNO₃ tiene una densidad de 1.32 g/mL (equivalente a 1320 g/L), donde la cantidad de masa es impura, se puede obtener la cantidad de masa de HNO₃ presente 1 L de la solución mediante el siguiente cálculo:

[tex]\frac{1320 g HNO_{3} impuro}{1 L}x \frac{70 g HNO_{3}puro}{100 g HNO_{3}impuro}= 924 \frac{g HNO_{3}puro}{L}[/tex]

Finalmente, la masa molar de HNO₃, es decir la masa presente en un mol de la sustancia, es 63 [tex]\frac{g}{mol}[/tex].

Entonces, teniendo en cuenta que la molaridad es el número de moles de soluto que están disueltos en un determinado volumen, es posible determinar la molaridad como:

[tex]\frac{924 g HNO_{3}puro}{L}* \frac{1 mol}{63 g}= 14.67 \frac{mol}{L}[/tex]

En resumen, la molaridad de la disolución es 14.67 [tex]\frac{mol}{L}[/tex]

Aprende más sobre la molaridad:

Answer: The given amount of [tex]Cd(NO_3)_2.4H_2O[/tex] contains 0.430 moles of Cd, 0.860 moles of N and [tex]2.59\times 10^{23}[/tex] molecules of water.

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

Given mass of [tex]Cd(NO_3)_2.4H_2O[/tex] = 132.4 g

Molar mass of [tex]Cd(NO_3)_2.4H_2O[/tex] = 308.5 g/mol

Plugging values in equation 1:

[tex]\text{Moles of }Cd(NO_3)_2.4H_2O=\frac{132.4g}{308.5g/mol}=0.430 mol[/tex]

1 mole of [tex]Cd(NO_3)_2.4H_2O[/tex] contains 1 mole of Cd, 2 moles of nitrogen atom (N), 10 moles of oxygen atom (O) and 8 moles of hydrogen atom (H).

So, 0.430 moles of [tex]Cd(NO_3)_2.4H_2O[/tex] will contain = [tex](1\times 0.430) = 0.430mol[/tex] of Cd and [tex](2\times 0.430)=0.86mol[/tex] of N

According to the mole concept:

1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules

So, 0.430 moles of [tex]Cd(NO_3)_2.4H_2O[/tex] will contain = [tex]\frac{6.022\times 10^{23}}{1mol}\times 0.430mol=2.59\times 10^{23}[/tex] number of water molecules.

Hence, the given amount of [tex]Cd(NO_3)_2.4H_2O[/tex] contains 0.430 moles of Cd, 0.860 moles of N and [tex]2.59\times 10^{23}[/tex] molecules of water.