a b c or d? help asap

Answer:

that answer is B

Explanation:

the answer is b luv

Answer:

b

Explanation:

Answer:

B. REFRACTION.

Is shown in fig.

Answer:

See explanation and image attached

Explanation:

Let us consider the mechanism attached to this answer. This is only one of the ways of synthesizing the required product.

The starting material is acetylene. This is reacted with sodamide in ammonia alongside methyl iodide. The process is repeated again, this time using butyl iodide. The alkyne is now reduced using hydrogen.

The alkane formed may now be chlorinated in the presence of light using the chlorine molecule. A mixture of alkyl halides are obtained.

Answer:

Glow sticks give off light but not heat because energy is released, the glow stick reaction is an example of exergonic (energy-releasing) reaction. However, it is not an exothermic (heat-releasing) reaction because heat isn't released... endothermic reactions absorb heat.

Explanation:

*Hope this helps*

Answer:

the mass of sodium fluoride is 15

Explanation:

One mole of F₂ or 38 g produces two moles or 84 g of NaF. Hence, 12.5 g of F₂ will produce 27.6 g of NaF.

Sodium fluoride is an ionic compound formed by the reaction of sodium metal and fluorine atom . Sodium metal loses one electron to fluorine and thus two moles of sodium and fluorine molecule produces 2 moles of NaF.

The molar mass of F₂ is 38 g. The molar mass of NaF is 42 g/mol. Thus mass of two moles of NaF is 84 grams. As per the balanced reaction, one mole or 38 g of F₂ produces two moles or 84 g of NaF. Thus mass of NaF is calculated as follows:

Mass of NaF = (12.5 g × 84 g) /38 g.

                     = 27.6 g.

Therefore, the mass of NaF produced by 12.5 g of F₂ in this reaction is 27.6 grams.

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Answer:

7.5 sec.

Explanation:

A = A₀e⁻^kt => k = ln(A/A₀)/-t => ln(6.25/100)/-30s = 0.0924 s⁻¹

k·t₀.₅=0.693 => t₀.₅=0.693/k = (0.693/0.0924)s = 7.5 s

The half life of an isotope can be calculated from the decay constant of . The half life of H-2 if only 6.25 % remains after 30 seconds is 17.25 seconds.  

Unstable radioactive isotopes undergo nuclear decay by emitting charged particles such as alpha particles or beta particles. The nuclear decay process results in a stable isotope or new atom.

It is given that the final amount of the isotope is 6.25% and and the time taken for the decay is 30 seconds. Let the initial amount be 100%.

The decay constant k can be calculated as follows:

k = 1/t log (100/6.25)

  =  1/30 s log 16

  = 0.0401 s⁻¹

Now, the half life time can be determined as below:

half life t1/2 = 0.693 /k

                   = 0.693 /0.0401 s⁻¹

                   = 17.25 seconds.

Hence, the half life time of the given H-2 isotope is 17.25 seconds.

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Answer:

It is false

Explanation:

Barium does not gain electrons to make its valences shell full. In truth, Barium loses electrons to attain a complete octet configuration of its shell.

This is because, barium is electropositive and not electronegative.

Answer:

Explanation:

MW of NaOH = 40 g/mol

MW of KCl = 74.55 g/mp;

250 mL = .25 L

100g NaOH / 40 g = 25 mol

100g KCl/ 74.55g = 1.34 mol

Molarity of NaOH: 25/.25 = 100M

Molarity of KCl: 1.34/.25 = 5.36 M

100M is the concentration of NaOH.

5.36 M is the concentration of  KCl.

Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per litres of a solution.

The scientific noun molarity describes the concentration of a substance as measured by the number of moles divided by the volume of the solution in litres.

[tex]Molality = \frac{Moles \;solute}{Volume\; of \;the \;solution \;in \;litres}[/tex]

Molecular weight of NaOH = 40 g/mol

Molecular weight of KCl = 74.55 g/mp;

250 mL = .25 L

100g NaOH ÷ 40 g = 25 mol

100g KCl ÷ 74.55g = 1.34 mol

Molarity of NaOH: 25 ÷ .25 = 100M

Molarity of KCl: 1.34 ÷ .25 = 5.36 M

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Answer:

Explanation:

Let the volume required be v litre .

moles of KOH in v litre of .558 M of KOH = v x .558 moles

1 mole of KOH reacts with 1 mole of HCl

v x .558 moles of KOH reacts with v x .558  mole of HCl

v x .558  = .016

v = .016 / .558

= .02867 litre

= 28.67 mL .

Answer:

1552.83J Released

Explanation:

1. mass/m=225

Initial temp:86C, final:32.5C

Changed Temp: 32.5-86= -53.5C

s=0.129 J/gC

Formula: q= m times s times changed Temp.

q=(225)(0.129)(-53.5)

q= -1552.83 J

q=1552.83 J Released

Answer:

 barium oxide < calcium oxide<  sodium chloride <   lithium chloride < aluminum oxide

Explanation:

The lattice energy can be defined as the change in internal energy accompanying the formation of a single mole of an ionic solid from its gaseous constituents at 0 K.

The lattice energy depends on the relative sizes of cations and anions in the compound. The smaller the cations and anions, the greater the lattice energy.

If we look as the proposed order of increasing lattice energy of the compounds;  barium oxide < calcium oxide<  sodium chloride <   lithium chloride < aluminum oxide, we will notice that it follows the order of decrease in the sizes of both the ions, Ba^2+ > Ca^2+ > Na+ >Li+ > Al^3+.

The smaller the ions involved, the greater the lattice energy as one can see from the order listed above.

Barium oxide < calcium oxide<  sodium chloride <   lithium chloride < aluminum oxide is the rank of salts in the increasing order of their lattice energy.

Lattice energy is define as the amount of internal energy required for the formation of one mole of ionic compound by its constitute ions.

Lattice energy is inversely proportional to the size of ions present in the ionic compound. In the given question order of size of ions are:

Ba²⁺ > Ca²⁺ > Na⁺ > Li⁺ > Al³⁺

From the above order it is clear that size of aluminum ion is smallest, so lattice energy for this ionic compound is more and sequence of salts in the increasing order of lattice energy is as follow:

barium oxide < calcium oxide<  sodium chloride <   lithium chloride < aluminum oxide

Hence, Aluminum oxide has highest lattice energy and barium oxide has minimum.

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0,15 moles of NaOH-------in------------1000ml

x moles of NaOH------------in--------100ml

x = 0,015 moles of NaOH

final volume = 150ml

0,015 moles of NaOH---in-------150ml

x moles of NaOH--------------in-----1000ml

x = 0,1 moles of NaOH

answer:  0,1mol/dm³  (molarity)

Answer:

when you drown your lungs fill up with water so it like severe pain that won't go away until your dead so it like drink milk through nose imagine that and you can't breath that is what it is like to drown

Explanation:

Answer:

Cr2(SO4)3

Explanation:

Answer:

1.86moles

Explanation:

Given chemical reaction:

   2C₂H₆  +  7O₂  →  4CO₂  +  6H₂O

Mass of C₂H₆   = 18.6g

Unknown:

Number of moles of steam produced  = ?

Solution:

  2C₂H₆  +  7O₂  →  4CO₂  +  6H₂O

 We have checked and the equation is balanced.

Now, find the number of moles of C₂H₆ from the given mass;

   Number of moles  = [tex]\frac{mass}{molar mass}[/tex]  

 Molar mass of C₂H₆ = 2(12) + 6(1) = 30g/mol

  Number of moles  = [tex]\frac{18.6}{30}[/tex]   = 0.62moles

From the balanced reaction equation:

      2 mole of C₂H₆ will produce 6 moles of steam

     0.62 moles of C₂H₆  will therefore produce [tex]\frac{0.62 x 6}{2}[/tex]   = 1.86moles

Answer:

15%

85%

Explanation:

Let the natural abundance of Fe-55  = y

      the natural abundance of Fe - 56  = 1-y

Average atomic mass = 55.85

Unknown:

Percent abundances of each isotope = ?

Solution;

The average atomic mass of a substance is given as;

  Average atomic mass  =  (mass x abundance)Fe - 55 + (mass x abundance)Fe - 56

Now insert the parameters and solve;

55.85  = (55 x y) + [56 x(1-y)]

 55.85  = 55y + 56 - 56y

 55.85  = -y + 56

  55.85 - 56  = -y

  -0.15 = -y

     y  = 0.15

1-y  = 1 - 0.15  = 0.85

Percentage abundance;

   Fe - 55  = 0.15 x 100  = 15%

   Fe - 56  = 0.85 x 100  = 85%

Answer:

the mirror is 12 cm away from the image

Explanation:

; the image will be virtual and it will form at 12 cm distance behind the mirror.

Answer:

15 days

Explanation:

Given half-life = 5 days => k = 0.693/half-life = 0.693/5 days⁻¹

A = A₀e^-k·t => t = ln(A/A₀) / -k = ln(1/8) / -0.1386 days⁻¹ =  15 days

The element with half life of 5 days have the decay constant of 0.1386 dy⁻¹ will take 15 days to decay to its 1/8th part of initial amount.

Heavy unstable radioactive isotopes undergo nuclear decay by the emission of charged particles. Nuclear decay is a first order reaction.

Thus, the decay constant k  = 1/t ln W0/Wt

where t is the time of decay, W0 be the initial amount and Wt be the amount after time t.

The half life of the element = 5 days.

decay constant = 0.693/t1/2

k = 0.693/5 days =  0.1386 days⁻¹.

The time taken to decay to 1/8th of its original amount is calculated as follows:

t = 1/k  ln Wo/(Wo/8 )

 = ln 8/0.1386 days⁻¹

 = 15 days.

Therefore, the days before the element decay to its 1/8th of original amount is 15 days.

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Answer:

C) 1 and 3

Explanation:

A period in the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. ... Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law.

Answer:

D) the higher the frequency the greater the energy of light.

Explanation:

Energy and frequency of light are directly connected. The higher the frequency ,the greater the energy of light.

As frequency increases, the energy of light also increases.

Mathematically;

 Energy  = hf

   h is planck's constant

   f is the frequency.

Answer: a + 2

Explanation: Alkali Earths or Group II has an ionization charge of a + 2. Alkali Metals have a ionization a + 1. Halogens or cold elements have a ionization of a +3.

Answer:

+4

Explanation:

Treatment of the ammonium metavanadate with hot hydrochloric acid partly reduces the vanadium to the +4 oxidation state in the form of the VO2+ ion.

In vanadium oxide we increase both sides by 4. And we discover that x is equal to five. The vanadium's oxidation number is + 5.

Loss of electron is called as oxidation. and addition of oxygen molecule is also the oxidation.

When an object comes into touch with oxygen or another oxidizer, a chemical reaction occurs. Rust and the brown color of a sliced apple are both examples of oxidation.

Antoine Lavoisier used the term "oxidation" to describe the reaction of a material with oxygen. The meaning was later expanded to cover additional reactions in which electrons are lost, regardless of whether oxygen was present, after it was realized that the substance loses electrons when it is oxidized.

Thus,  the oxidation number of vanadium in V₂O₅ is + 5.

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Answer: c

Explanation:

Answer:

Desertification  

Explanation:

I took the test

Desertification is the loss of fertile soil from drying out.

Desertification is the process where by the fertile soil is washed away and dry out because of overexposure and absence of trees to hold the soul together and drought.

Therefore, Desertification is the loss of fertile soil from drying out.

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Answer:

CuS(s) + 2HCl(aq) —> CuCl2(aq) + H2S(g)

Explanation:

CuS(s) + HCl(aq) —> CuCl2(aq) + H2S(g)

The above equation can be balance by by doing the following:

CuS(s) + HCl(aq) —> CuCl2(aq) + H2S(g)

There are 2 atoms of H on the right side and 1 atom on the left side. It can be balance by putting 2 in front of HCl as shown below:

CuS(s) + 2HCl(aq) —> CuCl2(aq) + H2S(g)

Now the equation is balanced since the number of atoms present in the elements are the same on both side of the equation i.e

Reactant:

Cu = 1

S = 1

H = 2

Cl = 2

Product:

Cu = 1

S = 1

H = 2

Cl = 2

Therefore, the balanced equation is:

CuS(s) + 2HCl(aq) —> CuCl2(aq) + H2S(g)

Answer:

What are the pages on? Like what topic?

Explanation:

Answer:

V₂  = 833.85 mL

Explanation:

Given data:

Initial volume V₁= 271 mL

Initial number of moles n₁= 0.26 mol

Final number of moles n₂= 0.80 mol

Final/new volume V₂ = ?

Solution:

V₁/n₁   =    V₂/n₂

Now we will put the values in formula.

271 mL / 0.26 mol = V₂ / 0.80 mol

V₂  = 271 mL × 0.80 mol / 0.26 mol

V₂  = 216.8 mL.mol /  0.26 mol

V₂  = 833.85 mL

Answer:

0.600 moles has volume 1.200L

Explanation:

The volume is numerically double the moles

0.600 mol occupies 1.200L

Mathematically:

V1/moles1 = V2/moles2

1.200L / moles1 = 0.600L/ 0.300mol

Moles 0.600L = 1.200L * 0.300mol

Moles = 1.2000L *0.300 mol / 0.600L

moles = 0.600 moles.

Answer:

Because of the existence of isotopes.

Answer:

Because of the existence of isotopes.