CBSE > Class 11 > Chemistry | CBSE Board | Homework Help

Shielding effect can be defined as a reduction in the effective nuclear charge on the electron cloud, due to a difference in the attraction forces of the electrons on the nucleus. It is also referred to as the screening effect (or) atomic shielding.

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What is enthalpy

Posted by Abhishek Tyagi 7 years ago

CBSE > Class 11 > Chemistry

4 answers

Ankit Singh 6 years, 11 months ago

Good defination yakshi in 1 line

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Yakshi ? 7 years ago

U can say enthalpy is a kind of energy in mininmum quantity i.e. 1 mole.

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???. Pragati 7 years ago

Enthalpy, the sum of the internal energy and the product of the pressure and volume of a thermodynamic system. ... If the only work done is a change of volume at constant pressure, the enthalpy change is exactly equal to the heat transferred to the system.

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Mr. Rajput 7 years ago

a thermodynamic quantity equivalent to the total heat content of a system. It is equal to the internal energy of the system plus the product of pressure and volume. the change in enthalpy associated with a particular chemical process. "most compounds have negative enthalpies of formation"

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Why there are so many lines in hydrogen spectrum?

Posted by Vibhanshu Vishal 7 years ago

CBSE > Class 11 > Chemistry

2 answers

Ankit Aryan Shivan 7 years ago

A hydrogen atom has only one electron it contains a large number of shells so when this single electron jumps from one shell to another,a photon is emitted,and the energy difference of the shells causes different wavelengths to be released. Hence mono-electric hydrogen has many spectrum lines.Transitions of electron in the hydrogen atom are 1.LYMAN series.2.Balmer.3.Paschen.4.Bracket.5.Pfund.6.Humphire series.

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Yogita Ingle 7 years ago

Hydrogen atom has one electron present in the first shell. When energy is given to the atom the electron gets excited and moves to a higher orbit. Excited states are unstable and quickly decay to the ground state i.e. the electron moves back to the first shell. This movement can either be in one step or a series of steps. The electron emits energy of a certain frequency when it falls from one energy level to another and for each movement it emits electromagnetic radiation of a certain frequency giving rise to a series of spectral lines each corresponding to the fall of excited electrons from one orbit to another. The spectral lines are divided into series depending on the shell the excited electron falls back to e.g. electrons that fall to the first shell from any of the higher shell, the spectral lines are called Lyman series. Balmer is the name for all lines where electrons move to shell 2 from higher orbits.

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Why group 2 elements of periodic table is known as alkali earth metal?

Posted by Vibhanshu Vishal 7 years ago

CBSE > Class 11 > Chemistry

2 answers

Amit Kumar 6 years, 11 months ago

Group 2 elements these are found earth crust

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Monica Bhatt 7 years ago

The hydroxides and oxides of group 2 are alkaline in nature and these metal oxides are found in earths crust..and hence known as alkali earth metals..

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Hybridisation of( CH3)2CO

Posted by Preeti Gupta 7 years ago

CBSE > Class 11 > Chemistry

1 answers

Nishu Godara 7 years ago

Sp3 and sp2 hybridisation

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Reaction of propene with hydrogen cyanide

Posted by Anushka Jaiswal 7 years ago

CBSE > Class 11 > Chemistry

0 answers

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What is meant by resonance in molecules?

Posted by Punit Dubey 7 years ago

CBSE > Class 11 > Chemistry

1 answers

Yogita Ingle 7 years ago

Resonance structures are two forms of a molecule where the chemical connectivity is the same but the electrons are distributed differently around the structure. Resonance occurs when electrons can flow through neighboring pi systems. An important example of resonance is found in the bonding of benzene, a planar six-membered ring with alternating double and single bonds (three of each). Two distinct pictures can be drawn, and the true structure of the molecule is a mixture of the two resonance structures. Having multiple valid resonance structures makes a molecule more energetically stable. Resonance helps to explain structure and reactivity of organic molecules.

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The strongest covalent bond is formed by the overlapping of 1 s and p 2 s and s 3 p and d 4 p and p

Posted by Monica Bhatt 7 years ago

CBSE > Class 11 > Chemistry

0 answers

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What do you mean by 15 volume h2o2 sol

Posted by Nidhi Dewangan 7 years ago

CBSE > Class 11 > Chemistry

1 answers

Sanvi Sharma 7 years ago

Means it'll liberate 150 ml of H2O2 at STP cond. Generally (x vol. & Y lit of H2O2 liberates xy lits of O2 Ex: 20V &20 ml of H2O2 gives 400 ml of O2 at STP. I hope u got it Nidhi.

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Resonance structure of fluro benzene

Posted by Ankit Dalal 7 years ago

CBSE > Class 11 > Chemistry

0 answers

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What is electron deficient and inert pair effect?

Posted by Kartik Saini 7 years ago

CBSE > Class 11 > Chemistry

4 answers

Ankit Singh 7 years ago

Nice explain yakshi

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Yakshi ? 7 years ago

Hpe u will read and it will become easy for u to understand the concept

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Yakshi ? 7 years ago

As we know that the meaning of inert is unreactive....similarly inert pair(of 2 electrons) effect can be defined as the tendency of pair of electrons in outermost or valence shell to remain unshared or unionised i.e remain unreactive

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Yakshi ? 7 years ago

Actually these are two different terms......."ELECTRON DEFICIENT molecule or species is definded as a molecule or species that does not have enough valence electrons to complete their octet and that's why they are very unstable and have tendency to accept a pair of elecron to achieve stable electronic configuration and behave as lewis acid....." for example ...BeCl2 and BCl3

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Formula of Borax??

Posted by ???. Pragati 7 years ago

CBSE > Class 11 > Chemistry

2 answers

Ankit Singh 5 years, 8 months ago

Na2[B4O5(OH)4]·8H2O hope this will help u

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Pavas Bhatnagar 7 years ago

Na2[B4O5(OH)4]·8H2O

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Why liquid diffuse slowly as compared to the gas

Posted by Neeraj Anand 7 years ago

CBSE > Class 11 > Chemistry

2 answers

Vikrant Singh 7 years ago

Bcoz liquid molecules are more closely packed than that of the gases

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Manujakshini Obalesh 7 years ago

Because the particles in liquid are tightly packed than in gas... Gas have loosen particles helps is faster diffusion

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What is half redox reaction

Posted by Tanu Singh 5 years, 8 months ago

CBSE > Class 11 > Chemistry

0 answers

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Why hydrogen is both metal or non metal

Posted by Kishan Singh 7 years ago

CBSE > Class 11 > Chemistry

7 answers

Ankit Singh 7 years ago

Yes answer is nice

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Aman Kumar 7 years ago

Thanks yakshi....I thought, If I m not conformed then there is no reason to give big explaination.............by the way nice answer

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Ankit Singh 7 years ago

Yet hydrogen has no fixed place ?

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Yakshi ? 7 years ago

It is non metal based on its physical property....as in group 1 (alkali) all elements have 1 electron in their outermost valence shell and hydrogen also does.......while based on chemical properties it can also react with.....non metals and form covalent as well as ionic compounds.....

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Yakshi ? 7 years ago

No aman ur answer is absolutely correct.....but u did not explain it

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Vikrant Singh 7 years ago

Bcoz it shows behaviour of both metals and non metals i.e. it can be placed in grp 1 as well as in grp 17

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Aman Kumar 7 years ago

Becoz Hydrogen can be placed in group 1 also as well as group 17 also.... If wrong then surely tell me....

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How does h2o2 behave as bleaching agent

Posted by Anmol Yadav 7 years ago

CBSE > Class 11 > Chemistry

1 answers

Yogita Ingle 7 years ago

H₂O₂ or hydrogen peroxide acts as a strong oxidizing agent both in acidic and basic media. When added to a cloth, it breaks the chemical bonds of the chromophores (colour producing agents). Hence, the visible light is not absorbed and the cloth gets whitened.

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ANSWER

Explain inductive effect with examples

Posted by Sunil Kumar 7 years ago

CBSE > Class 11 > Chemistry

2 answers

Sheetal Singh 6 years, 11 months ago

The generation of polarity c-c non polar bond due to attached any group which is either more nelectronegative than c are known as inductive effect Feature:- * It is parmanent effect. * It arises due to electronegative difference. * This effect decreases with distance and nearby dies of after 3 or 4 carbon atom. * Inductive effect is due to partial shifting of electrons and not due to complete transfer of electrons

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Yogita Ingle 7 years ago

Partial Transference of Electrons is called Inductive Effect. It usually occurs due to difference in Electronegativity of bonded atoms.

For example:

In CH₃Cl, Cl is more electonegative.
So, Cl will attract electrons towards it.
Here, -I effect is working.
-I effect increases the acidity while +I effect decreses the acidity.
Simultaneously, -I effect decreases the basicity while +I effect increases the basicity.

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Why is boric acid considered as a weak acid??

Posted by Prakhar Jadaun ? 7 years ago

CBSE > Class 11 > Chemistry

3 answers

Aman Kumar 7 years ago

Oookkkk ....nice yr....nice ques.and answer.??

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Priya Dharshini ? 7 years ago

Because it is not able to release H+ ions on its own. It receives oH- ions from water molecules to complete its octet and in turn releases H+ ions. It is solved question from ncert q11.4

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Gaurav Seth 7 years ago

Boric acid is considered as a weak acid as it contains lower concentration of hydrogen atoms as compared to other acids with equal concentration of water .Plus is shows lower acidity number on a P.H. scale (7-10). Because it is not able to release H+ ions on its own.

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Acidic radical ' reaction

Posted by Nirakshi Vashishtha 7 years ago

CBSE > Class 11 > Chemistry

1 answers

Himanshu Shekhar 7 years ago

?https://tse1.mm.bing.net/th?id=OGC.e46a42d68b80838dac8b3c504d6aac68&pid=Api&rurl=https%3a%2f%2fmedia.giphy.com%2fmedia%2fHld9vKjLk3irC%2fgiphy.gif&ehk=M2LOyINfUnub03J0nTb2Mw

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Why white fumes could be observed around the bottle of HCl solution?

Posted by Prakhar Jadaun ? 7 years ago

CBSE > Class 11 > Chemistry

2 answers

Priya Dharshini ? 7 years ago

It is solved question in ncert only..... pls refer those questions also it is important for ur exams.. aluminium chloride combines with air (hydrogen) forms hcl gas that is why white fumes appear around bottle

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Yogita Ingle 7 years ago

White fumes is due to the presence of HCl gas.Anhydrous aluminium chloride is hydrolysed partly with the moisture in the atmosphere to give HCl gas. This HCl combines with the moisture in the air appears white in colour.
AlCl₃ +3H₂O → Al(OH)₃ +3HCl(white fume)

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Why surface area increases down the group??

Posted by Prakhar Jadaun ? 7 years ago

CBSE > Class 11 > Chemistry

1 answers

Prakhar Srivastava 7 years ago

Because increase in size And we know that size is directly proportional to surface area

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How to make chlorophenylmethane

Posted by Aman Siddharth Rao 7 years ago

CBSE > Class 11 > Chemistry

0 answers

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Why alkynes acidic in nature

Posted by Sachin Janewa 7 years ago

CBSE > Class 11 > Chemistry

2 answers

Pinki Kumari 7 years ago

Is it right

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Pinki Kumari 7 years ago

I think alkynes are in first group and in first group there are all metals which have h+ so they

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Chemistry and mathematics best youtube channal Tell me

Posted by Aakash Mi 7 years ago

CBSE > Class 11 > Chemistry

3 answers

Teena Bagrwa 7 years ago

I would suggest coachengg and e vidyarthi

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Ayushi Ayushi 7 years ago

And for mathematics?

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???. Pragati 7 years ago

Hi gm ...yes Ankit u r right ✌️

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explain optical activity of lactic acid?

Posted by Mohammad Fahim Tayyab Ansari 7 years ago

CBSE > Class 11 > Chemistry

0 answers

ANSWER

explain wrutz reaction

Posted by Mohammad Fahim Tayyab Ansari 7 years ago

CBSE > Class 11 > Chemistry

1 answers

Ayushi Ayushi 7 years ago

Wurtz Reaction : When an alkyl halide is treated with metallic sodium in presence of dry ethyl ether , a symmetrical alkane is formed. Example : CH3CH2Cl+2Na+CH3CH2Cl➡CH3CH2CH2CH3+2NaCl

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Whatis inert pair effect

Posted by Robin Rajput 7 years ago

CBSE > Class 11 > Chemistry

4 answers

Robin Rajput 7 years ago

Hlo kaira

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Kaira Choudhary 5 years, 8 months ago

H r u

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Teena Bagrwa 7 years ago

Your most welcome sir

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Teena Bagrwa 7 years ago

The reluctance of (S)orbital to contribute in the bond formation is called inert pair effect It will work when (N) is greater than equal than 4

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Define Inductive effect ?

Posted by Jasmine Jasmine 5 years, 8 months ago

CBSE > Class 11 > Chemistry

6 answers

Aman Kumar 5 years, 8 months ago

Welcome??

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Jasmine Jasmine 7 years ago

Thanks ??

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Aman Kumar 5 years, 8 months ago

Hope this helps??

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Aman Kumar 7 years ago

Polarization of bond when a more or less electronegative atom or group bonded with carbon chain is called Inductive effect...........It is permanent effect..........Inductive effect decreases with increase in distance...It is of two types 1) + i effect and 2) - i effect.............

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Yogita Ingle 7 years ago

The inductive effect is the effect on electron density in one portion of a molecule caused by electron-withdrawing or electron-donating groups elsewhere in the molecule.

It usually occurs due to difference in Electronegativity of bonded atoms.

For example: