The group of elements that make up the smallest percentage of the periodic table are the

The mass of 5.15 × 10²¹ atoms of chromium is 0.44 g

From Avogadro's hypothesis,

6.02×10²³ atoms = 1 mole of Cr

But:

1 mole of Cr = 52 g

Thus, we can say that:

6.02×10²³ atoms = 52 g of Cr

With the above information, we can obtain the mass of 5.15 × 10²¹ atoms of chromium. This can be obtained as follow:

6.02×10²³ atoms = 52 g of Cr

Therefore,

5.15×10²¹ atoms = (5.15×10²¹ × 52) / 6.02×10²³

5.15×10²¹ atoms = 0.44 g of Cr

Thus, the mass of 5.15 × 10²¹ atoms of chromium is 0.44 g

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Answer:315 - 282 = 173?

Explanation:

As electron delocalization stabilizes the compound it is necessary that it takes place for compound to exist , hence the given statement is false.

Compound is defined as a chemical substance made up of identical molecules containing atoms from more than one type of chemical element.

Molecule consisting atoms of only one element is not called compound.It is transformed into new substances during chemical reactions. There are four major types of compounds depending on chemical bonding present in them.They are:

1)Molecular compounds where in atoms are joined by covalent bonds.

2) ionic compounds where atoms are joined by ionic bond.

3)Inter-metallic compounds where atoms are held by metallic bonds

4) co-ordination complexes where atoms are held by co-ordinate bonds.

They have a unique chemical structure held together by chemical bonds .Compounds have different properties as those of elements because when a compound is formed the properties of the substance are totally altered.

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To draw the Lewis dot structure on the [tex]B_aCO_3[/tex] molecular it is necessary to show the electron sharing between the [tex]CO_3[/tex] molecules, and then show the ionic bond between [tex]B_a[/tex] and [tex]CO_3[/tex].

You can see how this is done in the attached image.

We can arrive at this answer because:

Therefore, we can say that [tex]B_a[/tex] forms an ionic bond with [tex]CO_3[/tex].

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Answer:

Explanation:

D is the correct answer

The molarity of the acid, HCl solution is 0.103 M

We'll begin by calculating the number of mole in 0.2329 g of Na₂CO₃

Mass of Na₂CO₃ = 0.2329 g

Molar mass of Na₂CO₃ = (23×2) + 12 + (16×3) = 106 g/mol

Mole = mass / molar mass

Mole of Na₂CO₃ = 0.2329 / 106

Na₂CO₃ + 2HCl —> 2NaCl + H₂O + CO₂

From the balanced equation above,

1 mole of Na₂CO₃ reacted with 2 moles of HCl.

Therefore,

0.0022 mole of Na₂CO₃ will react with = 0.0022 × 2 = 0.0044 mole of HCl

Mole of HCl = 0.0044 mole

Volume = 42.87 mL = 42.87 / 1000 = 0.04287 L

Molarity = mole / Volume

Molarity of HCl = 0.0044 / 0.04287

Thus, the molarity of the acid, HCl solution is 0.103 M

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Answer:

In summary, yeast is a single-celled fungus that uses cellular respiration, which converts glucose and oxygen into carbon dioxide and ATP. ... Aerobic respiration makes the most ATP, between 36 and 38. Fermentation is anaerobic respiration and happens without oxygen.

Answer:

H3PO4 + 3KOH--------->  K3PO4 + 3H2O

Explanation

H3PO4 + KOH------------> K3PO4 + H20

when an hydrogen ion containing acid (HX) reacts with a hydroxide containing base(BOH)  they produce water and a "salt".

water can be called  dihydrogen oxide (H2O), but it can also be called

hydrogen hydroxide (HOH)...same thing.

so the phosphoric acid (H3PO4) contains 3 hydrogen ions (H), and needs 3

hydroxide ions to from 3 hydrogen hydroxides .. that is 3 waters AND A "SALT" WITH THE REMAINING SPECIES ( K AND PO4)      

so let us balance

H3PO4 + 3KOH--------->K3PO4 + 3HOH  or

H3PO4 + 3KOH--------->  K3PO4 + 3H2O

Check:

6 H on the left side, 6 H on the right side

1 P on the left side, 1 P on the right side

3 K on the left side, 3 K on the right side

7 O on the left side, 7 O on the right side

abadabaabdabadaba........that's all folks

yup it is balanced

Explanation:

At 25 °C Dissociation constant of water or Kw = 1× 10^-14 mol2dm-6

Ka × Kb = Kw for all diluted solutions

Ka×Kb = 1 × 10^-14 mol2dm-6

Therefore for question 1 -

COOH- is the conjugate base for HCOOH ( we find the conjugate base by removing an H atom and the Conjugate acid by adding an H atom)

COOH- (aq) + H2O ( l) <-----> HCOOH( aq) + OH-(aq)

So we can apply the above mentioned equation to find Kb value for COOH-

Kb = 5.56 × 10^-11 moldm-3

For question 2-

We can see that (CH3)2NH+2 is the conjugate acid of (CH3)2 NH. (A H atom has been removed so the one with a H atom less is the conjugate base.)

(CH3)2NH+2 (aq) + H2O (l) <-----> (CH3)2 NH (aq) + H3O+ (aq)

So applying the previously mentioned equation we get Ka = 1.85 × 10^-11 moldm-3

Answer:

------------------------------

Explanation:

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Answer:

All of the elements are radioactive and contain the transuranium elements.

Explanation:

N/A

Answer:

The mass of objects remains constant throughout the universe. This is because an object is made of he same amount of matter (atoms), no matter where you take it in the universe. If you take an object from the Earth to the moon, only the weight will change.

Explanation:

Answer:

ooooooooh .,.,.,.,.,.,

Answer:

True

TruePhysical change – A change in the size, shape, color, or state of matter of a substance. No new substance is produced.

The value of the work done in joule is 405.3 J.

We know that the work done is obtained using the relation;

w = PΔV

Where;

w = work done

P = pressure

V = volume

Now, substituting values,

w = 0.800( 15.0 -  10.0)

w = 4 atm L

Since;

1 L atm = 101.325 J

4 atm L  = 4 atm L × 101.325 J/1 L atm

= 405.3 J

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In this case, the problem is asking for the balance of a redox reaction in acidic media, in which nickel is reduced to a metallic way and nitrogen oxidized to an ionic way.

Thus, according to the given information, it turns out possible for us to balance this equation in acidic solution by firstly setting up the half reactions:

[tex]Ni^{2+}+2e^-\rightarrow Ni^0\\\\N^{3-}H_4^++3H_2O\rightarrow N^{5+}O_3^-+8e^-+10H^+[/tex]

Next, we cross multiply each half-reaction by the other's carried electrons:

[tex]8Ni^{2+}+16e^-\rightarrow 8Ni^0\\\\2N^{3-}H_4^++6H_2O\rightarrow 2N^{5+}O_3^-+16e^-+20H^+[/tex]

Finally, we add them together to obtain:

[tex]8Ni^{2+}+2N^{3-}H_4^++6H_2O\rightarrow 8Ni^0+2N^{5+}O_3^-+20H^+[/tex]

Which can be all simplified by a factor of 2 to obtain:

[tex]4Ni^{2+}+N^{3-}H_4^++3H_2O\rightarrow 4Ni^0+N^{5+}O_3^-+10H^+\\\\4Ni^{2+}(aq)+NH_4^+(aq)+3H_2O(l)\rightarrow 4Ni(s)+NO_3^-(aq)+10H^+(aq)[/tex]

Hence, the coefficients in front of Ni and H⁺ are 4 and 10 respectively.

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Answer:

Mercury has a relatively high vapour pressure and the highest volatility of any metal, vapourizing to become a colourless, odourless gas. The metal is a fair conductor of electricity, but a poor conductor of heat. Mercury's atomic number is 8.

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The correct choice is ~ A

S.I unit of time is Second

The heat produced by 4.5 moles of magnesium when burnt is 2700 kJ.

A thermochemical reaction is a reaction in which the amount of heat lost or gained is included in the reaction equation. The thermochemical reaction equation for the combustion of magnesium is shown as follows;

2 Mg(s) + O2(g) → 2 MgO(s) + 1200 kJ

From the reaction equation;

2 moles of magnesium produced 1200 kJ of heat

4.5 moles of magnesium will produce 4.5 moles × 1200 kJ/2 moles

= 2700 kJ

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My classmate's statement in incorrect because plants are also composed of cells.

All living things are composed of cells. A cell is the smallest unit of living organisms. Cells obtain energy via the process of cellular respiration. During cellular respiration, glucose is broken down to yield carbon dioxide and water.

In photosynthesis, carbon dioxide and water are combined to form glucose. The two processes are opposites of each other. Plants produce their own food via photosynthesis. Since plants are composed of cells, plant cells also undergo cellular respiration therefore my classmate's statement in incorrect.

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When the value of secondary quantum number (l) = 1, the magnetic quantum number can be from -1 to +1. The answer would be false.

The angular quantum number (l) can take any integer between 0 and the value of the principal quantum number (n) less by 1.

In other words, l can be from 0 to n-1.

The magnetic quantum number (m), on the other hand, can take any value between -l to +l.

For example, if l = 1, m can be -1,0, and +1.

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Answer:A versatile Ideal Gas Laws calculator with which you can calculate the pressure, volume, quantity (moles) or temperature of an ideal gas, given the other three. Free online gas law calculator a.k.a. PV = nRT calculator which accepts different input metric units such as temperature in celsius, fahrenheit, kelvin; pressure in pascals, bars, atmospheres; volume in both metric and imperial units ...

Answer:

The partial pressure of water is much less than 1atm, so the free energy change for the process must be negative with ΔGrxn<0.

Explanation:

Water vapor will condense into liquid water when the water vapor is in its standard state, with a pressure of 1atm. Under normal circumstances, the partial pressure of water vapor is much less that 1atm. It is in a nonstandard state. The free energy change of this reaction has to be negative in order to make the reaction spontaneous.

The criteria of the spontaneous process are the change in the Gibbs free energy should be negative. Above the normal boiling point, the TΔS will be greater than ΔH and ΔG<0.

Gibbs free energy can be described as a state function therefore it doesn’t depend on the path. The change in free energy is equal to the change in enthalpy minus the product of entropy change and temperature of the system.

ΔG = ΔH - Δ (TS)

If the process is carried out at constant temperature, ΔT = 0:

ΔG = ΔH – TΔS

ΔG > 0 for the reaction is non-spontaneous, ΔG < 0 for the reaction is spontaneous, exergonic and ΔG = 0 for the reaction is at equilibrium.

Spontaneous can be described as a reaction that occurs by itself without any external action towards it. The non-spontaneous process needs constant external energy applied to continue and as the external action, the process will cease.

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This problem is describing the equilibrium whereby the formartion of a complex is attained when 1.47 g of nickel(II) chloride is dissolved in 100.0 mL of ammonia so that the latter's equilibium concentration is 0.20 M. Thus, it is asked to calculate the equilibrium concentrations of both nickel(II) ions and that of the complex.

Firstly, we can write out the chemical equation to be considered:

[tex]Ni^{2+}+6NH_3\rightleftharpoons Ni(NH_3)_6^{2+}[/tex]

Next, we can calculate the initial concentration of nickel(II) ions by using the concept of molarity:

[tex][Ni^{2+}]=\frac{1.47gNiCl_2*\frac{1molNiCl_2}{129.6g}*\frac{1molNi^{2+}}{1molNiCl_2} }{0.1000L}=0.113M[/tex]

Afterwards, we set up an equilibrium expression for this chemical reaction:

[tex]Kf=\frac{[Ni(NH_3)_6^{2+}]}{[Ni^{2+}][NH_3]^6}[/tex]

Which can be written in terms of the reaction extent, [tex]x[/tex]:

[tex]Kf=\frac{x}{(0.113-x)(0.2)^6}[/tex]

Now, for the calculation of [tex]x[/tex], we plug in Kf, and solve for it:

[tex]1.2x10^9=\frac{x}{(0.113-x)(0.2)^6}\\\\1.2x10^9=\frac{x}{(0.113-x)(6.4x10^{-5})}\\\\7.68x10^4(0.113-x)=x\\\\x=0.112999 M[/tex]

Which is about the same to the initial concentration of nickel(II) ions because the Kf is too large.

Thus, the required concentrations at equilibrium are about:

[tex][Ni(NH_3)_6^{2+}]=0.113M[/tex]

[tex][Ni^{2+}]=0M[/tex]

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Answer:The law of conservation of energy

Explanation:

states that the total energy is constant in any process. Energy may change in form or be transferred from one system to another, but the total remains the same.

Answer:

C

Explanation:

Organic compounds are the compounds which are made only from carbon and hydrogen. The correct option is option D that is hydrocarbons are organic chemical compounds that consist of carbon and hydrogen.

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

There are two types of compound covalent compound and ionic in chemistry, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Hydrocarbons are organic compound. Hydrocarbon can have linear chain structure, ring structure or branched structure.

Therefore,  hydrocarbons are organic chemical compounds that consist of carbon and hydrogen. The correct option is option D.

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Specific chemical element

Answer:

The atomic mass of an element is the average mass of the atoms of an element measured in atomic mass unit (amu, also known as daltons, D). The atomic mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope.

Explanation:

Answer:

4:6

Explanation:

Answer:

Because oil have apolar molecules, while water have polar molecules

% Composition of elements:

Atomic mass of given elements:

Now, divide % composition by Atomic mass:

[tex]\footnotesize\implies Mg = \dfrac{\% \: Composition}{Atomic \: mass} = \dfrac{75}{24} = \bf 3.125[/tex]

[tex]\footnotesize\implies O = \dfrac{\% \: Composition}{Atomic \: mass} = \dfrac{25}{16} = \bf 1.5625[/tex]

Simplest Ratio:

[tex]\footnotesize\implies Mg = \dfrac{3.125}{1.5625} = 2[/tex]

[tex]\footnotesize\implies O = \dfrac{1.5625}{1.5625} = 1[/tex]

Empirical Formula:

[tex]\footnotesize\implies \underline{ \boxed{ \red{ \bf Empirical \: Formula = Mg_2O}}}[/tex]

The empirical formula will be [tex]Mg_{2}[/tex] .

The simplest entire number fraction of atoms contained in a chemical molecule is its empirical formula.

Calculation of empirical formula:

It is given that, composition of Mg = 75 %, composition of oxygen  = 25%.

It is known that, atomic mass of Mg = 24 g, atomic mass of oxygen = 16g.

By dividing % composition by atomic mass of given elements:

Mg = % composition / %atomic mass

= 75 / 24

= 3.125

Oxygen (O) = % Composition / atomic mass

= 25 / 1.56

Now, calculate simplest ratio of Mg and O.

For Mg = 3.125 / 1.56

= 2.

For O = 1.56 / 1.56

= 1

So, the empirical formula will be [tex]Mg_{2}O[/tex].

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