The element europium exists in nature as two isotopes: has a mass of u and has a mass of u. The average atomic mass of europium is u. Calculate the relative abundance of the two europium isotopes.

The solid that require the greatest energy input to melt by mass is the option;

Covalent network

Reason for the above answer is as follows;

The elementary particles of a solid are held together by bonds that require

an input of energy to unlock, and once broken, the particles are then able

to change location within their containing vessels with less restrictions

Types of bonds

a) Soluble in water b) Low melting point, b) Conduct electricity

a) High melting point temperature b) Non conductive of electricity c) Not soluble in water

a) High melting point temperature b) The liquid state and solution

conducts electricity c) Soluble in water

a) Low melting point b) Normally in the gaseous or liquid state b) Not water soluble

Therefore, the covalent network, and the solids ionic compounds require the most energy to melt, however, the strength of the ionic bond in an ionic compound is a factor the charges present and the sizes of the atom, while

the covalent network solid, are combined to form essentially as a single

molecule and therefore require the greatest heat energy input break the bonds of the molecule down in order to melt

Learn more about the properties of the different types of bonds here;

https://brainly.com/question/13510199

https://brainly.com/question/21628972

https://brainly.com/question/14823280

Answer:

In both cases, the gas evolved is H2. When calcium reacts with water the heat evolved is not suffcient for hydrogen to catch fire. On the other hand, sodium metal reacts with water violently and in this case a lot of heat is evolved which is sufficient for hydrogen to catch fire.

Explanation:

may this answer is helpful for you

Hydrogen

The reaction is given by

[tex]\boxed{\sf {Ca\atop Calcium}+{H_2O\atop Water}\longrightarrow {Ca(OH)_2\atop Calcium\:Hydroxide}+{H_2\atop Hydrogen}}[/tex]

Balanced equation:-

[tex]\boxed{\sf {Ca\atop Calcium}+{2H_2O\atop Water}\longrightarrow {Ca(OH)_2\atop Calcium\:Hydroxide}+{H_2\atop Hydrogen}}[/tex]

Answer:

22.1

Explanation:

Step 1: Calculate the number of formula units of lithium nitrate

A 5.08 L solution contains 2.68 × 10²¹ formula units per liter.

5.08 L × 2.68 × 10²¹ formula units/1 L = 1.36 × 10²² formula units

Step 2: Calculate the number of nitrate ions

Lithium nitrate dissociates completely in water according to the following equation.

LiNO₃(aq) ⇒ Li⁺(aq) + NO₃⁻(aq)

The molar ratio of LiNO₃ to NO₃⁻ is 1:1. The number of nitrate ions is 1/1 × 1.36 × 10²² = 1.36 × 10²².

Then,

log (1.36 × 10²²) = 22.1

The number of nitrate ions are present in the following aqueous solution is 13.6x10²¹, and log(base 10) value of this is 22.2.

Those salts which are completely dissociate into their ions in the solution form will known as strong electrolyte.

Lithium nitrate is a strong electrolyte and it shows complete dissociation as:

LiNO₃ → Li⁺ + NO₃⁻

Given that,

1 liter of solution containing = 2.68 x 10²¹ formula unit

5.08 L of solution containing = 5.08 x 2.68 x 10²¹ = 13.6x10²¹ formula unit

So, number of nitrate ion in given solution = 13.6x10²¹ formula unit

Log(13.6x10²¹) = 22.1

Hence, required values are 13.6x10²¹ and 22.1.

To know more about strong electrolytes, visit the below link:
https://brainly.com/question/5547666

Answer:C. distillation

Explanation:

Compounds having  different boiling points when  mixed can be separated by Fractional distillation.

Now when there is a mixture of  water and alcohol, Upon heat, we would see that the alcohol will boil at a lower temperature than water  for eg, ethanol will boil at 78.5 degrees Celsius, vaporizes and  distills into the fractionating columns leaving the  water which we know boils at 100 degrees  Celsius.

See related link here :https://brainly.com/question/13113349

Answer:

D. -80m/s^2

Explanation:

V = u + at

5 = 65 + a (0.75)

0.75a = -60

a = -60/0.75

a = -80m/s^2

Therefore, is decelerating at 80m/s^2

Answer:

[tex]\boxed {\boxed {\sf D. \ 80 \ m/s^2 \ down}}[/tex]

Explanation:

We are asked to find the acceleration of a skydiver. Acceleration is the change in velocity over the change in time, so the formula for calculating acceleration is:

[tex]a= \frac{v_f-v_i}{t}[/tex]

The skydiver was initially traveling 65 meters per second, then he slowed down to a final velocity of 5 meters per second. He slowed down in 0.75 seconds.

[tex]\bullet \ v_f = 5 \ m/s \\\bullet \ v_i= 65 \ m/s \\\bullet \ t= 0.75 \ s[/tex]

Substitute the values into the formula.

[tex]a= \frac{ 5 \ m/s - 65 \ m/s}{0.75 \ s}[/tex]

Solve the numerator.

[tex]a= \frac{-60 \ m/s}{0.75 \ s}[/tex]

Divide.

[tex]a= -80 \ m/s^2[/tex]

The acceleration of the skydiver is -80 meters per second squared or 80 meters per second squared down. The skydiver is slowing down or decelerating, so the acceleration is negative or down.

Explanation:

Since there are no gas constant with the unit of mmHg, you just have to use the gas constant for atm, and then convert that into mmHg

The amount, in grams, of Al that reacted with excess HCl if 3.86 L of hydrogen gas were collected at STP in the reaction would be 3.099 grams.

From the equation of the reaction, the mole ratio of Al that reacts with that of hydrogen gas that forms is 2:3.

At STP, 1 mole of any gas is equivalent to 22.4 Liters of the gas.

But only 3.86 L of hydrogen was formed in the reaction.

The equivalent mole of 3.86 L hydrogen at STP would be:

      3.86 x 1/22.4 = 0.1723 moles

From the mole ratio, the equivalent mole of Al that will produce 0.1723 moles of hydrogen gas would be:

          0.1723 x 2/3 = 0.1149 moles

Recall that: mass = mole x molar mass

Mass of 0.1149 moles Al = 0.1149 x 26.98

                                        = 3.099 grams

Thus, the amount of Al that reacted with excess HCl is 3.099 grams.

More on stoichiometric problems can be found here: https://brainly.com/question/28297916

#SPJ1

Answer:

A

Explanation:

helium (alpha particle)

Answer:

[tex]{ \sf{A. \: 2OH {}^{ - } _{(aq)} +Ca {}^{2 + } _{(aq)} −>Ca(OH) _{2(s)} }}[/tex]

The chemical equations depict a balanced ionic equation is  2OH−+Ca2+−>Ca(OH)2. option A is correct.

An ionic equation is a chemical equation in which the electrolytes in an aqueous solution are expressed as dissociated ions. The ions in aqueous solutions are stabilized by ion-dipole interactions with water molecules

Strong acids, strong bases, and soluble ionic compounds (usual salts) exist as dissociated ions in an aqueous solution, and Weak acids and bases and insoluble salts are usually written using their molecular formulas because only a small amount of them dissociates into ions.

Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) → AgCl(s) + Na+(aq) + NO3-(aq) is an ionic equation example.

Therefore, the balanced ionic reaction will be  2OH−+Ca2+−>Ca(OH)2. option A is correct.

Learn more about ionic reactions, here:

https://brainly.com/question/13887096

#SPJ5

Answer: Hợp chất CTHH 0 °C 10 °C 20 °C 30 °C 40 °C 50 °C 70 °C

Actini(III) hydroxide Ac(OH)3   0,0022    

Amonia NH3 1176 900 702 565 428 333 188

Amoni azua NH4N3 16  25,3  37,1  

View 42 more rows  

                    hehe

Answer:

By definition, a pure substance or a homogeneous mixture consists of a single phase. A heterogeneous mixture consists of two or more phases. When oil and water are combined, they do not mix evenly, but instead form two separate layers.

Explanation:

Sorry only knew the answer to the first question

Answer:

To make a saturated solution, 36 gm of sodium chloride is dissolved in 100 gm of water at 293 K. Find its concentration at this temperature.

Mass per cent is a way of expressing a concentration or describing the component in a particular mixture. The solution composition can be expressed in mass percentage that depicts the mass of solute present in a given mass of solution.

The quantity of solute is expressed in mass or by moles. For a solution, the mass per cent is described as the grams of solute per grams of solution, multiplied by 100 to get the percentage.

Concentration

Mass of sodium chloride (Solute) = 36gm

Mass of water (solvent) = 100 gm

Mass of solution = 36+100

∴ Mass of solution = 136 gm

Concentration = (Mass of Solute / Mass of Solution) * 100

Concentration = (36/136) × 100

Concentration = 26.47%

Temperature

If temperature increases, solubility increases and if temperature decreases, solubility decreases.

It is possible to distinguish the particles of solute from those of solvent in a suspension, since particle size is bigger in suspensions, hence it is easier to distinguish the particles of solute.

Explanation:

Answer:

See explanation

Explanation:

The IUPAC name of aspirin is 2-Acetoxybenzoic acid. It is composed of an acetoxy moiety and a benzoic acid moiety.

The compound can be hydrolysed under prolonged storage conditions to yield acetic acid which causes the vinegar like odour.

Also, one of the products of this hydrolysis bears a phenol group which reacts with FeCl3 to give a purple color.

Answer:

Each molecule of O2 is made up of 2 oxygen atoms. So 1 mole of O2 molecules is made up of 2 moles of oxygen atoms. Therefore 1 mole of oxygen gas contains 2 moles of oxygen atoms. And 0.4 moles of oxygen gas contains 0.8 moles of oxygen atoms.

There are 0.8 moles of oxygen atoms in 0.4 moles of oxygen gas.

Oxygen gas (O₂) consists of two oxygen atoms bonded together. Therefore, to determine the number of moles of oxygen atoms present in a given amount of oxygen gas, we can simply multiply the number of moles of oxygen gas by the number of oxygen atoms per molecule, which is 2.

Given that we have 0.4 moles of oxygen gas, we can calculate the number of moles of oxygen atoms as follows:

Number of moles of oxygen atoms = Number of moles of oxygen gas × Number of oxygen atoms per molecule

= 0.4 moles × 2

= 0.8 moles

Therefore, there are 0.8 moles of oxygen atoms present in 0.4 moles of oxygen gas.

This calculation is based on the stoichiometry of oxygen gas, which indicates that each molecule of O₂ contains two oxygen atoms. By considering the mole ratio between oxygen gas and oxygen atoms, we can determine the number of moles of oxygen atoms in a given quantity of oxygen gas.

To learn more about moles, here

https://brainly.com/question/34302357

#SPJ2

Answer:

1. Because the rules will keep you safe it prevents you from getting hurt.

2.i) don't taste chemical

ii) Always wear protective gears

iii) be careful with tool

iv) wear protective gloves

Explanation:

help everyone get out quickly

Answer:

Methane and chlorine

If a mixture of methane and chlorine is exposed to a flame, it explodes - producing carbon and hydrogen chloride. This is not a very useful reaction! The reaction we are going to explore is a more gentle one between methane and chlorine in the presence of ultraviolet light - typically sunlight. This is a good example of a photochemical reaction - a reaction brought about by light.

CH4+Cl2+energy→CH3Cl+HCl(3.4.2)

The organic product is chloromethane. One of the hydrogen atoms in the methane has been replaced by a chlorine atom, so this is a substitution reaction. However, the reaction doesn't stop there, and all the hydrogens in the methane can in turn be replaced by chlorine atoms.

Substitution reactions happen in which hydrogen atoms in the methane are replaced one at a time by chlorine atoms. You end up with a mixture of chloromethane, dichloromethane, trichloromethane and tetrachloromethane.

I hope this help you!:)

Explanation:

Using boyles law

[tex]\boxed{\sf v\propto \dfrac{1}{p}}[/tex]

[tex]\\ \sf\longmapsto P_1V_1=P_2V_2[/tex]

[tex]\\ \sf\longmapsto P_2=\dfrac{P_1V_1}{V_2}[/tex]

[tex]\\ \sf\longmapsto P_2=\dfrac{2.8\times 1.5}{0.92}[/tex]

[tex]\\ \sf\longmapsto P_2=\dfrac{4.2}{0.92}[/tex]

[tex]\\ \sf\longmapsto P_2=4.56atm[/tex]

[tex]\\ \sf\longmapsto P_2\approx 4.6atm[/tex]

Answer:

[tex]\boxed {\boxed {\sf 4.6 \ atm}}[/tex]

Explanation:

We are asked to find the new pressure given a change in volume. We will use Boyle's Law, which states the volume of a gas is inversely proportional to the pressure. The formula for this law is:

[tex]P_1V_1= P_2V_2[/tex]

Initially, the gas occupies 1.5 liters at a pressure of 2.8 atmospheres.

[tex]1.5 \ L * 2.8 \ atm = P_2V_2[/tex]

The volume is changed to 0.92 liters, but the pressure is unknown.

[tex]1.5 \ L * 2.8 \ atm = P_2* 0.92 \ L[/tex]

We are solving for the final pressure, so we must isolate the variable P₂. It is being multiplied by 0.92 liters. The inverse operation of multiplication is division, so we divide both sides by 0.92 L.

[tex]\frac {1.5 \ L * 2.8 \ atm}{0.92 \ L} = \frac{P_2* 0.92 \ L}{0.92 \ L}[/tex]

[tex]\frac {1.5 \ L * 2.8 \ atm}{0.92 \ L}= P_2[/tex]

The units of liters cancel each other out.

[tex]\frac {1.5 * 2.8 \ atm}{0.92 }=P_2[/tex]

[tex]\frac {4.2}{0.92} \ atm= P_2[/tex]

[tex]4.565217391 \ atm = P_2[/tex]

The original measurements of pressure and volume have 2 significant figures, so our answer must have the same. For the number we calculated, that is the tenths place. The 6 in the hundredth place tells us to round the 5 up to a 6.

[tex]4.6 \ atm \approx P_2[/tex]

The pressure is approximately 4.6 atmospheres.

Answer:

HClO₃(aq) + NaOH(aq) ⇒ NaClO₃(aq) + H₂O(l)

Explanation:

We have the products of a reaction and we have to predict the reactants. Since the products are salt and water, this must be a neutralization reaction. In a neutralization reaction, an acid reacts with a base. To form NaClO₃, the acid must be HClO₃(aq) and the base NaOH(aq). The balanced chemical equation is:

HClO₃(aq) + NaOH(aq) ⇒ NaClO₃(aq) + H₂O(l)

Answer:

The front passenger airbag has a volume of around 140 l and fully inflates in around 35 ms. The process is similar for side airbags (thorax airbags).

H2CO3 is an acid because it gave away a proton to become HNO3~.

HNO3~ is a conjugate Base because Acids become conjugate Bases after giving away a proton.

C5H5N is a base because it accepted the proton from H2CO3 to become HC5H5N+.

HC5H5N+ is a conjugate Acid because Bases become Conjugate Acids after accepting a proton.

Answer:

A. tungsten

Explanation:

Tungsten is a material which high melting point ie. does not melt easily incase of high temperature

Answer:

option(A):Tungsten

Explanation:

tungsten has highest melting point.

Answer:

See explanation and image attached

Explanation:

Methyl butanoate is an ester. Esters have the general molecular formula, RCOOR where the two Rs may represent the same or different alkyl groups.

Methyl butanoate is has a fruity odor, smelling like apples or pineapples fragrance. It is also called methyl butyrate.

The structure of the compound is shown in the image attached to this answer.

Answer:

The independent variable of an experiment is the one that is intentionally changed or manipulated to see the results of changing said variable.

We are told that in each different group, the amount of caffeine that is given to the dog's changes - in the control group, they get no caffeine, in the 2nd group, they get 10 mg of caffeine each, and in the 3rd group, they get 50 mg of caffeine each.

Therefore, since the amount of caffeine that is given to the dogs is the only variable that is being manipulated, this is the independent variable.

Answer: The independent variable of an experiment is the one that is intentionally changed or manipulated to see the results of changing said variable.

The independent variable of an experiment is the one that is intentionally changed or manipulated to see the results of changing said variable.

We are told that in each different group, the amount of caffeine that is given to the dog's changes - in the control group, they get no caffeine, in the 2nd group, they get 10 mg of caffeine each, and in the 3rd group, they get 50 mg of caffeine each.

Therefore, since the amount of caffeine that is given to the dogs is the only variable that is being manipulated, this is the independent variable.

We are told that in each different group, the amount of caffeine that is given to the dog's changes - in the control group, they get no caffeine, in the 2nd group, they get 10 mg of caffeine each, and in the 3rd group, they get 50 mg of caffeine each.

Therefore, since the amount of caffeine that is given to the dogs is the only variable that is being manipulated, this is the independent variable.

Explanation:

Answer:

81°C

111°C

cyclohexane

Explanation:

Distillation is a process of separating two liquids based on differences in Bolling point. For two substances having different boiling points, they are collected as they are converted into vapour, condensed and move down the condenser one after the other.

Since the boiling point of cyclohexane is less than that of toluene, cyclohexane is collected first before toluene.

Answer:

[H₃O⁺] = [H⁺] = 10^-pH = 10⁻¹°⁸⁶ = 0.0138M in [H⁺]  

Explanation:

By definition pH = -log[H⁺] => [H⁺] = 10^-pH = 10⁻¹°⁸⁶ = 0.0138M in [H⁺]

Using your calculator ... I am using a TI-30XA scientific calculator.

Depending on the calculator, the answer may show as 0.0138, or  1.38x10⁻², or 1.38E-2 (=1.38 x 10⁻²). It is the user's job to insert dimensional units into answer of interest =>  0.0138M, or  1.38 x 10⁻²M, or 1.38E-2M.

1.38E-2 which is 1.38 x 10⁻².

Explanation:

Physical change

★ Boiling of water

❤︎ freezing of water

❣︎ washing of clothes

♫︎ mixing black and brown stones

Chemical change

➪ making of dough

㋛︎ burning of wood

❥︎ cooking of the raw food

❁ burning of paper

ꨄ︎ rusting of iron

★★★➪➪➪➪ it was help to you

Answer:

It obeys rule

Explanation:

Benzene is an aromatic hydrocarbon because it obeys Hückel's rule.

Answer:

Benzene is an aromatic compound because it is planar, cyclic, conjugated and has (4n +2) π electrons, where n= 1.

Explanation:

Hückel's rule states that a molecule is aromatic if it is planar, cyclic, conjugated and has (4n +2) π electrons.

Breaking it down into 4 requirements, we have:

Let's look at each of the 4 parts!

What is planar?

Planar refers to the molecule being flat. When an atom is sp² hybridized, it is in a trigonal planar geometry. Let's look at the benzene molecule. Each carbon is attached to 3 other atoms, namely 2 carbons and 1 hydrogen. This means that each carbon is sp² hybridized, making the molecule planar.

Cyclic

This refers to the molecule having a closed ring shape. Benzene fulfils this criteria.

Conjugation

This refers to a system of connected p orbitals, which allows π electrons to delocalize. Each carbon atom in benzene has one 2p orbital, making benzene a conjugated molecule. For molecules that are not cations or anions, conjugated molecules are those that have alternating single and double bonds.

(4n +2) π electrons

n is an integer (e.g. 0, 1, 2, 3) thus for the molecule to be aromatic, it can have 2, 6 or 10 π electrons (non exhaustive). This separates an aromatic compound from an antiaromatic compound, which has 4n π electrons instead.

Benzene has 6 π electrons, so n has a value of 1 in this case.

Thus, benzene is an aromatic compound because it is planar, cyclic, conjugated and has (4n +2) π electrons.

_______

Counting the number of π electrons

Let's look at π bonds!

A double bond is made up of 1 σ bond and 1 π bond, and each π bond is made up of 2 π electrons. We do not count the number of single bonds since single bonds are made up of 1 σ bond only.

There are 3 double bonds in the Kekulé structure of benzene. Thus, the number of π electrons in benzene is 3(2)= 6.

Attached diagrams

Answer:

D) these all have the same boiling point

Answer:

с

Explanation:

the first quantum number of an electron gives the information about the energy level the electron is in

The information first quantum number of an electron give is the energy level the electron is in.

Quantum numbers is a set of symbols which gives idea about the position  of electron present inside an atom.

Hence first quantum number of electron gives ideal about the energy level.

To know more about quantum numbers, visit the below link:
https://brainly.com/question/11575590

Answer:

C

Explanation: