CBSE > Class 12 > Chemistry | CBSE Board | Homework Help

Histamine is a chemical which is responsible for allergic response towards pollen, associated with nasal congestion at the time of cold and is also a potent vasodilator

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Sparsh Anand 8 years, 2 months ago

Antibody released by body due to any allergy

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Mr. Shivanshu yadav share your viva questions of chemistry

Posted by Sweety Yadav 8 years, 2 months ago

CBSE > Class 12 > Chemistry

7 answers

Shivanshu Yadav 8 years, 2 months ago

Muskan apka kb h practical hm

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Muskan Bhardwaj 8 years, 2 months ago

Shivanshu please tell Ur viva questions

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Shivanshu Yadav 8 years, 2 months ago

Kk I give your question in free time hmm

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Sweety Yadav 8 years, 2 months ago

Maybe upto this 29.. Not sure

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Shivanshu Yadav 8 years, 2 months ago

Plz give me your date of practical and i give your important questions for practical kk

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Shivanshu Yadav 8 years, 2 months ago

Some ph value put up

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Sweety Yadav 8 years, 2 months ago

School time Guys

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ANSWER

Please tell me about them

Posted by Aastha Singh 8 years, 2 months ago

CBSE > Class 12 > Chemistry

11 answers

Aastha Singh 8 years, 2 months ago

And pahele se best of luck ? ?

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Aastha Singh 8 years, 2 months ago

Ok please tell me about after done your viva ok

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Sweety Yadav 8 years, 2 months ago

Kl physics ka h

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Aastha Singh 8 years, 2 months ago

Mera 27 ko h phsics ka

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Aastha Singh 8 years, 2 months ago

Kisi subject ka

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Aastha Singh 8 years, 2 months ago

Anyways tmhara practical hua

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Sweety Yadav 8 years, 2 months ago

Apka Kon s subject ka h

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Aastha Singh 8 years, 2 months ago

Ok and thanks

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Sweety Yadav 8 years, 2 months ago

Maybe he became offline.. Uska messaging time dekh k lgta h wo 11:00 se 12:00 k beech m aayega

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Aastha Singh 8 years, 2 months ago

Ya sister dekha h pr kuch aur question poochne h Vineet bhai se

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Sweety Yadav 8 years, 2 months ago

Kl usne btaya tha

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ANSWER

Hello Vineet bhai kaisa hua practical

Posted by Aastha Singh 8 years, 2 months ago

CBSE > Class 12 > Chemistry

1 answers

Sweety Yadav 8 years, 2 months ago

See more chatting

1Thank You

ANSWER

how should i prepare for the viva of chemistry and which topic or chapter i should learn

Posted by Nitika Thakur 8 years, 2 months ago

CBSE > Class 12 > Chemistry

2 answers

Himanshu Bhandari 8 years, 2 months ago

Learn the chapter in which you are suitable and know each and every point of it. And viva contains only 4 marks the other are in your school teaches hands.

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Shivanshu Yadav 8 years, 2 months ago

Which school?

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ANSWER

what is spectrochemical series? Write difference between weak field ligand and strong field ligand?

Posted by Vikash Kumar 8 years, 2 months ago

CBSE > Class 12 > Chemistry

1 answers

Sia ? 4 years, 9 months ago

Weak field ligands induce less splitting of the crystal fields. They form complexes with high spins.

Examples: chloride ions, fluoride ions etc.

Strong field ligands result in greater splitting of the crystal field. They form complexes with low spins.

Examples: Co and cyanide ion.

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ANSWER

How can you prepare orangnic in chemistry.

Posted by Nishi Boudha 8 years, 2 months ago

CBSE > Class 12 > Chemistry

2 answers

Muskan Bhardwaj 8 years, 2 months ago

By making notes

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Sweety Yadav 8 years, 2 months ago

By more and more practice.. Specially name rxn

2Thank You

ANSWER

What is denatured alcohol

Posted by Lokesh Yadav 8 years, 2 months ago

CBSE > Class 12 > Chemistry

2 answers

Arushi Chaudhary 8 years, 2 months ago

So..the above answer is absolutely correct...but mainly..cuso4 is added to give the colour to it and pyridine is used to give foul smelling to the denatured alcohol..!!

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Vanshika Lamba 8 years, 2 months ago

The alcohol that is made unfit for drinking purpose by adding copper sulphate and pyridine is called denatured alcohol

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ANSWER

VBT of Mn(Cn)6

Posted by Nitik Kumar 8 years, 2 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

No there is not CBSE 12 class previous board exam paper of 2017 of set 1,2and 3......... There is only compartment paper ....plz publish board paper of chemistry of 2017 right now...

Posted by Ajay Bohra 8 years, 2 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

Different between evaporation and vapourztion

Posted by Priyadarshini S 8 years, 2 months ago

CBSE > Class 12 > Chemistry

2 answers

Ravi Singh 8 years, 2 months ago

Vaporization is the convertion of molecules into gas at every step of reaction And the process in which at certain temperature the energetic molecules have tendency to escape from the surface of liquid is called evaporation

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Ishika Tanwani 8 years, 2 months ago

Eva.is at particular temp.and vap.is at every temp.

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ANSWER

Why potassium superoxide is paramagnetic

Posted by Priyanka Suthar 8 years, 2 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

Effect of concentration on conductivity of ions

Posted by Ishika Tanwani 8 years, 2 months ago

CBSE > Class 12 > Chemistry

1 answers

Abhishek Chaurasia 8 years, 2 months ago

First increase with inc in conc. then decreasing with more increase of conc. due to inc in ion ion interaction

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ANSWER

Please mention all important topics of organics

Posted by Angel D 8 years, 2 months ago

CBSE > Class 12 > Chemistry

1 answers

Singh Singh 8 years, 2 months ago

Refer pardeep part2 appendix

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ANSWER

Are chemical properties important for boards

Posted by Angel D 8 years, 2 months ago

CBSE > Class 12 > Chemistry

1 answers

Navjot Kaur 8 years, 2 months ago

Yes

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ANSWER

what is the name of (cr(nh3)5nsc)(zncl4)

Posted by Gurkirat Singh 8 years, 2 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

Why PCL5 all bonds are not equivalent

Posted by Rahul Mahlan 8 years, 2 months ago

CBSE > Class 12 > Chemistry

2 answers

Arushi Chaudhary 8 years, 2 months ago

If u see the structure of pcl5..which is trigonal bipyramidal.. U will see that three cl are present at equitorial positions and two cl atoms r present at axail positions and the bond length of axial bonds r longer bcz...to avoid bond pair bond pair repulsions that's why.... Oll Bonds in pcl5 r not equivalent...! I hope..u will get my point.. !

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Ishika Tanwani 8 years, 2 months ago

Coz it is sp3d in which acusl nd equ.bond lenths r diff.

3Thank You

ANSWER

What is monochloride?

Posted by Abhi Kharkwal 8 years, 2 months ago

CBSE > Class 12 > Chemistry

1 answers

Ishika Tanwani 8 years, 2 months ago

An alkane with 1 Cl

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ANSWER

Can i get a question paper of practical examination of last year

Posted by Jay Maurya 8 years, 2 months ago

CBSE > Class 12 > Chemistry

3 answers

Aastha Singh 8 years, 2 months ago

Okk thanks and best of luck??

1Thank You

Jay Maurya 8 years, 2 months ago

Tommorow 23 jan

2Thank You

Aastha Singh 8 years, 2 months ago

Bhai kish date ko h aap ka practical

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ANSWER

Aryle hellide can'not form hydrogen bonding . Yes or not .

Posted by Mohit Tiwari 8 years, 2 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

how to prepare in last month for boards?

Posted by Khushboo Kabra 8 years, 2 months ago

CBSE > Class 12 > Chemistry

2 answers

Asim Khan 8 years, 2 months ago

I believe that atleast one month before the board exams, we are expected to cover all the main concepts and theory part. And now the question arises that what to do in the last remaining month? I would suggest you to give your last one month only and only on solving the previous year board papers and sample papers. It will help you in better understanding all the main concepts and will give you the idea about the most important part of the topic which is being asked again and again in last ten or fifteen years,etc. Moreover it will boost your speed and accuracy which is the most important tool for a topper. Thank you! Hope it helps you... Best wishes

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Prajjwal Tripathi 8 years, 2 months ago

Study the major scoring part firstly...unless leaving them

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How ionisation enthalpy varies in d block elements

Posted by Nikita Pandro 8 years, 2 months ago

CBSE > Class 12 > Chemistry

2 answers

Asim Khan 8 years, 2 months ago

The second ionization enthalpy for Cr and Cu are quite higher as the d5 and d10 configuration of M+ ions gets disrupted whereas, the value for Zn is correspondingly low as the ionization consists of the removal of an electron which allows the production of the stable d10 configuration. The trend in third ionization enthalpy doesn’t involve 4s orbitals and thus there is a greater difficulty for the removal of an electron from Mn2+ (d5) and Zn2+ (d10) ions. Thus, we see a marked difference between third ionization enthalpies of iron (26) and manganese (25).

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Asim Khan 8 years, 2 months ago

Ionisation Enthalpy: Ionisation enthalpy is the energy required to remove the most loosely bound electron from the isolated gaseous atoms to produce a cation. Those of transition elements tend to increase from left to right in the periodic table as there is an increase in nuclear charge which accompanies the filling of the inner d orbitals. However, there are some exceptions, for example, Titanium (22) has first ionization enthalpy of 656kJ/mole whereas vanadium (23) has first ionization enthalpy of 650kJ/mole. Enthalpy Periodic table These irregular trends in the first ionization enthalpy of transition metals can be explained by considering the fact that the removal of one electron alters the relative energies of 4s and 3d orbitals. Hence, in general, we can conclude that the unipositive ions furnish dn configuration with no 4s electrons. Thus, there is a reorganization energy accompanying ionization with some gains in exchange energy as the number of electrons increases from the transference of s electrons into d orbitals. Let us analyze the general trend in the first row: First ionization enthalpies of transition elements show general trend of increase from left to right. However, in case of chromium (24), the change in the value of first ionization enthalpy is lower as there is no change in d orbital configuration whereas, zinc (30) shows a higher value as it represents an ionization from 4s level

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Which has higher boiling point? CH3NH2 and (CH3)3N.

Posted by Ankit Maurya 8 years, 2 months ago

CBSE > Class 12 > Chemistry

4 answers

Ankit Maurya 8 years, 2 months ago

But molecular mass of (CH3)3N is much higher than that of CH3NH2

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Vikram Choudhary 8 years, 2 months ago

CH3NH2 H-bonding in water

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Varun Narang 8 years, 2 months ago

CH3NH2 will have the higher boiling point as it forms hydrogen bond with water molecules whereas hydrogen bonds are absent in case of (CH3)3N as there is no hydrogen attached with nitrogen which can form the bonds.

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Nikita Pandro 8 years, 2 months ago

CH3NH2 has higher boiling point than (CH3)3N because in 1degree amine 2 H are available for H bonding

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Basic nature of amines in gas phase??? What is the decreasing order?

Posted by Aakash Poonia 8 years, 2 months ago

CBSE > Class 12 > Chemistry

2 answers

Asim Khan 8 years, 2 months ago

The correct order of increasing basic nature for the bases NH3, CH3NH2 and (CH3)2NH is CH3NH2 < (CH3)2NH < NH3 CH3NH2 < NH3 < (CH3)2NH (CH3)2NH < NH3 < CH3NH2 NH3 < CH3NH2 < (CH3)2NH Answer Except the amines containing tertiary butyl group, all lower aliphatic amines are stronger bases than ammonia because of +I (inductive) effect. The alkyl groups, which are electron releasing groups, increase the electron density around the nitrogen thereby, increasing the availability of the lone pair of electrons to proton or Lewis acids and making the amine more basic. The observed order in the case of lower members is found to be as secondary > primary > tertiary. This anomalous behavior of tertiary amines is due to steric factors i.e. crowding of alkyl groups cover nitrogen atom from all sides and thus makes it unable for protonation. Thus the relative strength is in order (CH3)2NH > CH3NH2 > NH3.

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Nikita Pandro 8 years, 2 months ago

3,2,1,NH3

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Give iupac name and structure of anime obtained when 3cholobutanamide undergoes Hoffman bromamide reaction

Posted by Shona Dethe 8 years, 2 months ago

CBSE > Class 12 > Chemistry

1 answers

Asim Khan 8 years, 2 months ago

It will be 2-Chloropropanamine because the third carbon will become the second carbon after the removal of the carbon of the amide group. Structure: CH3-CH(Cl)-CH2-NH2

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Transition metals act as catalyst

Posted by Vaishali Yadav 8 years, 2 months ago

CBSE > Class 12 > Chemistry