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

Only molality is temperature independent. Others are temperature dependent because there values depend upon volume and volume is temprature dependent.

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What happens when lanthanum is heated with sulphur

Posted by Aditya Sharma 6 years, 3 months ago

CBSE > Class 12 > Chemistry

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What is safe selective catalysis .

Posted by Rajnish Kumar 6 years, 3 months ago

CBSE > Class 12 > Chemistry

1 answers

Yogita Ingle 6 years, 3 months ago

A catalytic reaction which depends upon the pore structure of the catalyst and on the size of the reactant and the product molecules is called shape-selective catalysis. For example, catalysis by zeolites is a shape-selective catalysis. The pore size present in the zeolites ranges from 260-740 pm. Thus, molecules having a pore size more than this cannot enter the zeolite and undergo the reaction.

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Name tha metal used as reducing agent for MnO2

Posted by Radha Gupta 6 years, 3 months ago

CBSE > Class 12 > Chemistry

1 answers

Yash Surya 6 years, 3 months ago

Carbon

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What is henery law

Posted by Kp Singh Yadav 6 years, 3 months ago

CBSE > Class 12 > Chemistry

2 answers

Gaurav Seth 6 years, 3 months ago

Henry’s Law establishes aquantitative relation betweenpressure and solubility of a gasin a solvent.
This law is for gas-liquid solution.
According to the law at a constant temperature, thesolubility of a gas in a liquid is directly proportional to thepressure of the gas.
It can also be stated as - The partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution.
Mathematically,

p = K_H x where K_H= Henry’s law constant.

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Radha Gupta 6 years, 3 months ago

Ghghh

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Propanone is treated with dil. Ba(OH)2 ???

Posted by Yuvraj Singh 6 years, 3 months ago

CBSE > Class 12 > Chemistry

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Please send me the blueprint of chemistry

Posted by Pragati Chaudhary 6 years, 3 months ago

CBSE > Class 12 > Chemistry

2 answers

Ankur Dahiya 6 years, 3 months ago

Yes, he is right. Man Har told u correctly.

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Man Har 6 years, 3 months ago

Solution,electrochemistry,chemical kinetics, surface chemistry is of 23 marks General principle and processes of isolation of elements ,P-block elements,D-and F-block elements ,Co-ordination compounds is of 19 marks Ful part 2 (all organic) of chemistry is of 28 marks

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At 333k and 1 atm of N2O4 is 50% dissociated into NO2 then Kp is

Posted by Ns H 6 years, 3 months ago

CBSE > Class 12 > Chemistry

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Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a stronger acid than phenol. Give two reasons

Posted by Tushar Verma 6 years, 3 months ago

CBSE > Class 12 > Chemistry

1 answers

Abhay Mehta 6 years, 3 months ago

Because in carboxylate negative charge is more dispersed over two oxygen atom whereas in phenoxide only on one oxygen atom

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Name the unit formed by the attachment of base 1' position of sugar in a nucleoside.

Posted by Vidyanshu Sinha 6 years, 3 months ago

CBSE > Class 12 > Chemistry

3 answers

Ankur Dahiya 6 years, 3 months ago

This question is in sampe paper published by cbse under free sample papers section. And cbse provided answers also. Answer is Nucleotide.

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Ankur Dahiya 6 years, 3 months ago

Nucleotide

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Yogita Ingle 6 years, 3 months ago

A nucleoside is one of the structural components or building blocks of DNA or RNA. A nucleotide consists of a base (one of the four bases: adenine, thymine, guanine, and cytosine) and a molecule of sugar and phosphoric acid. They are formed by the attachment of a base to 1’ position of sugar in a nucleoside.

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Syllabus which has been removed

Posted by Kapil Dalal 6 years, 3 months ago

CBSE > Class 12 > Chemistry

4 answers

Vipul Kumar Maurya 6 years, 3 months ago

Then why about 15th group is given in P Block revision notes??? This note should be according to syllabus.

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Pragati Chaudhary 6 years, 3 months ago

Mechanisms of polymer

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Pragati Chaudhary 6 years, 3 months ago

15th group elements of p-block

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Sujal Samdarshi 6 years, 3 months ago

Solid states

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How inter halogen compound formed ? What general composition can be assigned to them ?

Posted by Pragati Chaudhary 6 years, 3 months ago

CBSE > Class 12 > Chemistry

1 answers

Ankur Dahiya 6 years, 3 months ago

First, 5:02 AM, what time is this friend. Were you studying the whole night or u wake up early? ?? Second, halogen is represented by R-X. Also known as haloalkanes maybe. Thats it. I just know this. Inform me when u get the answer.????

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Give reason Oxygen has less electron gain with negative sign than sulphur

Posted by Pragati Chaudhary 6 years, 3 months ago

CBSE > Class 12 > Chemistry

3 answers

Shubham Rajput 6 years, 3 months ago

This is because of small size of oxygen as a result of which electrons of oxygen experiences repulsions among themselves and the incoming electron experiences it to;thus causing electron gain enthalpy to decrease (less negative)

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Vishal Pathak 6 years, 3 months ago

Also The electron gain enthalpy decreases down the group ..

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Vidyanshu Sinha 6 years, 3 months ago

Because of the compact nature of oxygen atom, it has less - ve electron gain enthalpy than sulphur.

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On hydrolysis of RNA, no relationship among the quantities of different bases are obtained. Analyse the given information and suggest the structure of RNA.

Posted by Soyab Ali 6 years, 3 months ago

CBSE > Class 12 > Chemistry

0 answers

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How to end all chapters in 2 months

Posted by Suraj Gupta 6 years, 3 months ago

CBSE > Class 12 > Chemistry

3 answers

Parul Singh 6 years, 3 months ago

Complete atleast 2 chapter in one day

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Geetanjali Rathod 6 years, 3 months ago

We are having only 60 day ...and 45 appox chapter in main subject...so lear your self...one or two chapter daily and end of the day just review and do practice of chapter que...but give first priority to ncert

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Rishabh Gupta 6 years, 3 months ago

Study 10 hours per day Make a timetable for studies

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Primary anime distngush

Posted by Rohan Sharma 6 years, 3 months ago

CBSE > Class 12 > Chemistry

1 answers

Vanshita Gupta 6 years, 3 months ago

You can use carbylamine reaction as it does give any reaction with secondary and tertiary amine or go for hinsberg reagent

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Conversation of propanoic acid to ethanoic acid

Posted by Shun Shine Sharma 6 years, 3 months ago

CBSE > Class 12 > Chemistry

1 answers

Aasta Chouhan 6 years, 3 months ago

Propanoic acid react NH3 In heat to give propanamide which umder go offman bromide degradation to form ethanamine On reacting with nanO2 AND hcl give ethanol which on oxidation with kmno4 Give ethanoic acid

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What do you mean by dancing resonance?

Posted by Ns H 6 years, 3 months ago

CBSE > Class 12 > Chemistry

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Yogita Ingle 6 years, 3 months ago

The resonance involving delocalization of sigma electrons (unlike the usual delocalization of pi electrons) is known as sigma resonance or dancing resonance. Eg. Resonance in cyclopropylmethyl carbocation.

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Why are halogen coloured

Posted by Pragati Chaudhary 6 years, 3 months ago

CBSE > Class 12 > Chemistry

4 answers

Ankur Dahiya 6 years, 3 months ago

Pragati, colour is obtained by any metal or non metal by d orbital configuration. You can understand it in chapter 8 i.e. d- and f- block elements.

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Vivekanand Yadav 6 years, 3 months ago

Most halogens are coloured because tjey absorb light from visible region.

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Pankaj Ku 6 years, 3 months ago

d d transtion

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Yogita Ingle 6 years, 3 months ago

Most of the halogens are coloured because they absorb radiations which are in the visible region which in turn excite the valence electrons to higher energy levels. As the amount of energy which is required to excite the electrons to a higher level is different for different halogens, each halogen has a different colour.

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What is chittar

Posted by Sameer Khan 6 years, 3 months ago

CBSE > Class 12 > Chemistry

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Why aluminium cannot be reduced by carbon

Posted by Ashna Khan 6 years, 3 months ago

CBSE > Class 12 > Chemistry

1 answers

Yogita Ingle 6 years, 3 months ago

Carbon isn't utilized for diminishing aluminum oxide since aluminum is more responsive than carbon.

Thus, carbon can't uproot aluminum from its oxide.

Aluminum oxide is exceptionally steady and Carbon is less responsive than aluminum, hence it can't be utilized to diminish aluminum oxide to aluminum metal.

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H2S is a toxic gas with rotten egg like smell is used for the qualitative analysis. If the solubility of H2s in water a stp is 0.195 m calculate henty'sLaw cinstant

Posted by Ankit Arya 6 years, 3 months ago

CBSE > Class 12 > Chemistry

1 answers

Yogita Ingle 6 years, 3 months ago

given, Molality =0.195 m,

Let take mass of solvent (water) = 1 kg

Use above formula we get

Moles of solute = 0.195 mol

Molar mass of water (H2O ) = 2 × 1 + 16 = 18

Mass of water (mass of solvent 1 kg = 1000 g

Number of moles of water = 1000 g / 18 = 55.56 mol

Use above formula we get

Mole fraction of H2S = 0.195/(0.195 + 55.56) = 0.0035

At STP, pressure (p) = 0.987 bar always

According to Henry’s law:

p = KH × X

KH = p / X = 0.987 / 0.0035 = 282 bar

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2-bromo-2-methylpropane

Posted by Nitin Kumar 6 years, 3 months ago

CBSE > Class 12 > Chemistry

2 answers

Geetanjali Rathod 6 years, 3 months ago

Now u try the structure and send

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Geetanjali Rathod 6 years, 3 months ago

1st ..there is prop means 4 carbon atom then at second position methyl and bromo is attached (CH3 and Br ) =CH3C(CH3)(Br)CH2CH3...and check the carbon full with 4 valance atom...

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Describe aldol condensation

Posted by M S 6 years, 3 months ago

CBSE > Class 12 > Chemistry

2 answers

Yogita Ingle 6 years, 3 months ago

Aldol condensation occurs in aldehydes having α-hydrogen with a dilute base to give β-hydroxy aldehydes called aldols. This reaction is most commonly known as aldol condensation. If the condensation reaction occurs between two different carbonyl compounds it is called crossed aldol condensation.

Aldol Condensation can be defined as an organic reaction in which enolate ion reacts with a carbonyl compound to form β-hydroxy ketone or β-hydroxy aldehyde, followed by dehydration to give a conjugated enone. Aldol Condensation plays a vital role in organic synthesis, creating a path to form carbon-carbon bonds.

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Simardeep Singh 6 years, 3 months ago

Aldol condensation means, condensation of alcohol and aldehyde to form alkene

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What are chemical

Posted by Jitendra Chauhan 6 years, 3 months ago

CBSE > Class 12 > Chemistry