4. What is valency? Explain different types of
valencies​

Answer: Boiling point, because it can be observed by altering the state of the substance

Explanation:

Physical property is defined as the property of a substance which becomes evident during physical change in which there is alteration in shape, size etc. No new substance gets formed during physical change. Example: Melting point

Chemical property is defined as the property of a substance which becomes evident during chemical change in which a change in chemical composition takes place. A new substance is formed in these reactions. Example: Reactivity with other substances

Thus Boiling point is a propertywhich can be examined without altering the composition, because it can be observed by altering the state of the substance

Answer:

The formula for the compound isB6Br7

Answer:

The word 'pinniped' means 'fin foot', as the four legs of seals, sea-lions and walrus have developed into flippers to better suit their life in the water. They are not fish! Even though a great part of their life is spent in the sea, pinnipeds are warm blooded air-breathing mammals known as marine mammals.

Explanation:

Sea lions (left) are brown, bark loudly, "walk" on land using their large flippers and have visible ear flaps. Seals have small flippers, wriggle on their bellies on land, and lack visible ear flaps. ... Both seals and sea lions, together with the walrus, are pinnipeds, which means "fin footed" in Latin.

To solve this we must be knowing each and every concept related to sea lions. Therefore, due to above given reason,  seals and sea lions are not considered fish.

Sea lions are curious creatures with sleek bodies that are playful as well as acrobatic in behavior. The species that can be found in aquariums and zoos the most frequently are California sea lions, who enthrall visitors with their antics. This captivating animal possesses a variety of extraordinary traits that are just amazing. Learn more about this sea lion by reading on.

Scaled fish have a cold blooded constitution. Their bodies are streamlined, and they breathe underwater. Fur covers seals and sea lions. They are warm blooded and breath air.

Therefore, due to above given reason,  seals and sea lions are not considered fish.

To know more about  sea lions, here:

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#SPJ2

Answer:

IV

Explanation:

The complete question is shown in the image attached.

Let us call to mind the fact  that the SN1 mechanism involves the formation of carbocation in the rate determining step. The order of stability of cabocations is; tertiary > secondary > primary > methyl.

Hence, a tertiary alkyl halide is more likely to undergo nucleophilic substitution reaction by SN1 mechanism since it forms a more stable cabocation in the rate determining step.

Structure IV is a tertiary alkyl halide, hence it is more likely to undergo nucleophilic  substitution reaction by SN1 mechanism.

Answer:

Q1 D

Explanation:

Q2 C

Answer:

B

Explanation:

uncontrolled energy damage the body

Answer: causes destruction

Explanation:

Answer:

lhigygygigy

Explanation:

hyfgutfytifytftyfjgfhjfv

Answer:

it is true because i just took the test and i did research on it

Explanation:

i study this and because i did research

Answer:

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Explanation: eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

Answer:

Since the 3s if now full we'll move to the 3p where we'll place the remaining five electrons. Therefore the Chlorine electron configuration will be 1s22s22p63s23p5. The configuration notation provides an easy way for scientists to write and communicate how electrons are arranged around the nucleus of an atom.

Heat required to raise temperature : 224.02 J

Given

mass CCl4 = 4.66 g

Δt= 76.8 - 20.9 =55.9 °C

c = The specific heat capacity of CCl4 = 0.856 J/g◦C.

Required

Heat /energy required

Solution

Heat can be formulated

Q=m.c.Δt

[tex]\tt Q=4.66\times 0.86\times 55.9\\\\Q=224.02~J[/tex]

There are 2 grams remain

Given

t1/2 = 30 years

t = 170 years

No = 100 g

Required

Remaining sample

Solution

General formulas used in decay:  

[tex]\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}[/tex]

Input the value :

[tex]\tt Nt=100.\dfrac{1}{2}^{170/30}\\\\Nt=1.969\approx 2~grams[/tex]

Answer:

Energy released by 1 g of U-235 = 7.603 * 10¹⁰ J

Explanation:

Uranium-235, U-235 undergoes neutron-induced fission to give the following products:

1 neutron + ²³⁵U --> ¹⁴¹Ba + ⁹²Kr + 3 neutrons

Masses of reactants and products:

neutron = 1.009 amu, uranium-235 = 235.044 amu, Ba-141 = 140.910 amu, Kr-92 = 91.910 amu

mass defect = mass of reactants - mass of products

mass defect = (235.044 + 1.009) - (140.910 + 91.910 + 3 * 1.009)

mass defect = 236.053 - 235.847 = 0.206 amu

1 amu = 1.6 * 10⁻²⁷ kg

Using E = mc²

E = 0.206 * 1.6* 10⁻²⁷ kg * (3 * 10⁸ m/s)² = 2.966 * 10⁻¹¹ J

therefore, 1 atom of U-235 releases 2.966 * 10⁻¹¹ J of energy

energy released by 1 g of U-235 can be calculated as follows:

1 mole or 253 g  of U-235 contains 6.02 * 10³ atoms

1 g of U-235 will contain 6.02 * 10³/235 = 2.563 * 10²¹ atoms

Energy released by 1 g of U-235 = 2.563 * 10²¹ * 2.966 * 10⁻¹¹ J = 7.603 * 10¹⁰ J

Answer:

A) An electrolytic cell, because it absorbs energy.

Explanation:

The major difference between an electrolytic cell and a voltaic cell is that, in an electrolytic cell, there must be input of energy from outside (a cell) to drive the non spontaneous reaction while in a voltaic cell, the reaction proceeds on its own and releases energy which could be harnessed to do work.

Hence, considering the equation; 2H2O+ electricity → 2H2 + O2 , energy is supplied as electricity in order for the process to take place. This is an example of an electrolytic cell.

Answer:

a)215000

b) 3.2

c) 2.08

d) 27439.74

Explanation:

Significant figures:

When we add or subtract the values the number of significant figures after decimal in result must be equal to the given measurement having less number of decimal places.

b) 5.45 -2.3

3.2

d) 14.98 + 27,340 + 84.7593

27439.74

When we multiply or divide the values the number of significant figures must be equal to the less number of significant figures in given value.

a) 628 × 342

214776

we will round off this value into 3 significant figures.

215000

c) 28.0/13.483

2.08

Answer: Thus 8.41 g was the mass of the original sample

Explanation:

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]

[tex]\text{Moles of} O_2=\frac{3.29g}{32g/mol}=0.103moles[/tex]

[tex]2KClO_3\rightarrow 2KCl+3O_2[/tex]  

According to stoichiometry :

As 3 moles of [tex]O_2[/tex] are produced by = 2 moles of [tex]KClO_3[/tex]

Thus 0.103 moles of [tex]O_2[/tex] are produced by =[tex]\frac{2}{3}\times 0.103=0.0687moles[/tex]  of [tex]KClO_3[/tex]

Mass of [tex]KClO_3=moles\times {\text {Molar mass}}=0.0687moles\times 122.5g/mol=8.41g[/tex]

Thus 8.41 g was the mass of the original sample.

8.41 grams is the mass of original sample of KClO₃.

Mass of any substance will be calculated from the moles as:

n = W/M, where

W = given or required mass

M = molar mass

Given chemical reaction is:

2KClO₃ → 2KCl + 3O₂

Given mass of O₂ = 3.29g

Moles of O₂ = 3.29g/16g/mole = 0.103 moles

From the stoichiometry of reaction, it is claer that:

3 moles of O₂ = produced by 2 moles of KClO₃

0.103 moles of O₂ = produced by 2/3×0.103 = 0.0687 moles of KClO₃

Now mass of KClO₃ = 0.0687 × 122.5g/mol = 8.41g

Hence, 8.41g is the mass of KClO₃.

To know more about moles, visit the below link:

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Answer:

"nonmetal, nonmetal"

Explanation:

Oxygen is a non metal and Nitrogen is a non metal. It is 8th element of the periodic table. It is located in period 2 and group 16.

Nitrogen lies at the group 15 of the periodic table. Its atomic no is 7. Its valency is 2.

Hence, the correct option is (c) "nonmetal, nonmetal".

Answer:

How could you prepare 250 mL of 0.20M NaCl using only a solution of 1.0M NaCl and water? To prepare a 250 mL 0.20 M NaCl solution, I would place 50 mL of the 1.0 stock solution to a 250 mL volumetric flask and then add 200 mL of water. A bottle of the antiseptic hydrogen peroxide (H2O2) is labeled 3.0% (v/v).

The answer is C.less -- freeze -- less​

Answer:

As2S5

Explanation:

I hope this is the answer.

Answer:

[Kr] 4d² 5s²

Explanation:

Answer:

-Cations: They are formed by an atom losing an electron or electrons.

-Anions: They are formed by an atom gaining an electron or electrons.

Answer:

5.38 g of CO.

Explanation:

From the question given above, the following data were obtained:

Volume of CO = 4.3 L

Mass of CO =?

Next, we shall determine the number of mole of CO that occupied 4.3 L at STP. This can be obtained as follow:

Recall = 1 mole of any gas occupy 22.4 L at STP.

1 mole of CO occupied 22.4 L at STP.

Therefore, Xmol of CO will occupy 4.3 L at STP i.e

Xmol of CO = 4.3 / 22.4

Xmol of CO = 0.192 mole.

Thus, 0.192 mole of CO occupy 4.3 L at STP.

Finally, we shall determine the mass of CO as follow:

Mole of CO = 0.192 mole.

Molar mass of CO = 12 + 16 = 28 g/mol

Mass of CO =?

Mole = mass /Molar mass

0.192 = mass of CO / 28

Cross multiply

Mass of CO = 0.192 × 28

Mass of CO = 5.38 g.

Therefore, 5.38 g of CO occupied 4.3 L at STP.

Answer:

c. I and Ill

Explanation:

SN1 mechanism is a unimolecular nucleophillic substitution reaction mechanism. "Unimolecular" implies that only one molecule is involved in the rate determining step and that is the alkyl halide. The rate determining step of SN1 reaction is the formation of a carbocation which subsequently reacts with a nucleophile in the fast step.

SN1 reactions occur mostly with tertiary alkyl halides due to sterric reasons. SN2 mechanism involves a crowded transition state because it is a concerted reaction mechanism. This is not possible in a tertiary alkyl halide due to the presence of bulky groups around the tertiary carbon atom hence tertiary alkyl halides do not undergo nucleophilic reaction by SN2 mechanism.

Secondly, polar solvents aid in the ionization of the alkyl halide thus assisting in the formation of the carbocation which participates in the second step of the reaction.

The mass of the Pbl2 : 1308.87

Given

18.2 mL of a 0.156 M Pb(NO3)2

26.2 mL of a 0.274 M KI

Reaction

Pb(NO3)2 (aq) + 2 KI (aq) - Pbl2 (s) + 2 KNO3

Required

the mass of the Pbl2

Solution

mol Pb(NO3)2 = 18.2 x 0.156 = 2.8392 mlmol

mol KI = 26.2 x 0.274 =7.1788 mol

Limiting reactant Pb(NO3)2(smaller ratio of mol : reaction coeffiecient)

mol Pbl2 based on limiting reactant (Pb(NO3)2)

From equation, mol ratio of Pb(NO3)2 : Pbl2 = 1 : 1, so mol Pbl2=mol Pb(NO3)2=2.8392

Mass Pb(NO3)2 :

[tex]\tt mass=mol\times MW\\\\mass=2.8392\times 461\\\\mass=1308.87~grams[/tex]

Answer:

In its astrobiology roadmap, NASA has defined the principal habitability criteria as "extended regions of liquid water, conditions favorable for the assembly of complex organic molecules, and energy sources to sustain metabolism". In August 2018, researchers reported that water worlds could support life.

Answer:

I think it is c

Explanation:

I'm sorry if I'm wrong had to look up aquifers

aquifer-a body of permeable rock which can contain or transmit groundwater

landfills, agricultural regions, and gas stations can contaminate an aquifer.

The aquifer is a layer of liquid rock beneath the earth. Underground water is contaminated by excavation and quarrying, increased fertilizer use, and septic tank leakage.

Therefore, the correct choices are "Option B, Option C, and Option E".

Find out more about the contamination here:

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Answer:

a) SN1/H2O

b) SN1/CH3OH

c)SN2/DMF

d)SN2/HMPA

Explanation:

The reactions are shown in the image attached.

Let me restate the basic facts about SN1 and SN2 reaction mechanisms. SN1 reaction occurs by unimolecular mechanism and involves a carbocation, a poor nucleophile and a polar protic solvent.

An SN2 reaction is a bimolecular synchronous reaction that passes through a single transition state. It requires a good nucleophile and a polar aprotic solvent.

For reaction a and b, we  observe that the alkyl halide is tertiary hence the reaction occurs by SN1 mechanism in the presence of a polar protic solvent.

Reactions c and d involves primary and secondary alkyl halides respectively and good nucleophiles. The best solvents to be used are polar aprotic solvents and the reaction follows SN2 mechanism.