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

In crystallisation , it seperates a pure solid in form of its crystals from solution.but in evaporation , some impurities remain dissolved in solution even after evaporation.so , that's why crystallisation is better technique.

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Kamlesh Kumar Sharma Kamlesh Kumar Sharma 6 years, 7 months ago

Xef4 structure

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Iupac name of (ch3)2--ch.chcl--ch3

Posted by Sandeep Singh 6 years, 7 months ago

CBSE > Class 12 > Chemistry

1 answers

Bhavya Tiwari 6 years, 7 months ago

Iupac name is 2-chloro 3-methyl butane

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Normality of 10% w/v acetic acid

Posted by Udit Parashar 6 years, 7 months ago

CBSE > Class 12 > Chemistry

1 answers

Sia ? 6 years, 7 months ago

For example, to prepare 100 mL of a 10% by volume solution of acetic acid, dilute 10 mL acetic acid with distilled or deionized water to make 100 mL of solution. Note: Solutions of concentrated reagents, such as 37% hydrochloric and 85% phosphoric acids, are percent solutions by mass.

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Kya pure no. 70 in 2020 cbse board me la sakte h only reading ncert

Posted by Yash Garg 6 years, 7 months ago

CBSE > Class 12 > Chemistry

1 answers

Bhavya Tiwari 6 years, 7 months ago

No, u must read sidebook and scanner too.

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Benzene and ccl4 are polar or non polar

Posted by Pan Singh 6 years, 7 months ago

CBSE > Class 12 > Chemistry

6 answers

Bhavya Tiwari 6 years, 7 months ago

It just by mistake , answer is both are polar

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Bhavya Tiwari 6 years, 7 months ago

Both are non-polar

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Deepak Jindal 6 years, 7 months ago

Both are non polar...???????

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Neeraj Sanyal 6 years, 7 months ago

Both are Non-polar

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Nishu Sahu 6 years, 7 months ago

Both are non polar

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Tapan Pandey 6 years, 7 months ago

Both are polar

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acetone and water together on mixing gives evolution of heat

Posted by Pan Singh 6 years, 7 months ago

CBSE > Class 12 > Chemistry

1 answers

Bhavya Tiwari 6 years, 7 months ago

Yes, it is miscible in water because acetone has a carbonyl group which is a carbon double bonded to oxygen.

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H2S a toxic gas with rotten egg like smell is used for the qualitative analysis . If the solubility of H2S in water at STP is 0.195m calculate henry's law constant.

Posted by Monika M 6 years, 7 months ago

CBSE > Class 12 > Chemistry

1 answers

Sia ? 6 years, 7 months ago

The solubility of H₂S gas = 0.195 m = 0.195 moles of H₂S is dissolved in 1 kg of water (solvent).
1 kg of solvent contains = {tex}\frac { 1000 } { 18 }{/tex}= 55.55 moles
Moles fraction of H₂S gas in solution =
{tex}x _ { \mathrm { H } _ { 2 } \mathrm { S } } = \frac { n _ { \mathrm { H } _ { 2 } \mathrm { S } } } { n _ { \mathrm { H } _ { 2 } \mathrm { S } } + n _ { \mathrm { H } _ { 2 } \mathrm { O } } }{/tex}{tex}= \frac { 0.195 } { 0.195 + 55.55 } = \frac { 0.195 } { 55.745 }{/tex}= 0.0035
Pressure at STP = 0.987 bar = 1 atm
{tex}p _ { \mathrm { H } _ { 2 } \mathrm { s } } = \mathrm { K } _ { \mathrm { H } } \times x _ { \mathrm { H } _ { 5 } ; \mathrm { K } _ { \mathrm { H } } } = \frac { 0.987 \mathrm { bar } } { 0.0035 }{/tex}= 282 bar
Thus, the Henry's constant = 282 bar

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Is baking soda and cooking soda one other same?

Posted by Macherla Indupriya 6 years, 7 months ago

CBSE > Class 12 > Chemistry

4 answers

K@Łp@N@ $Øđh!?? 6 years, 7 months ago

Yes

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Bhavya Tiwari 6 years, 7 months ago

Yes, both are same cooking soda is a common name for baking soda

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Deepak Jindal 6 years, 7 months ago

Yes...?????

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Tapan Pandey 6 years, 7 months ago

Yes because cooking soda is common name of baking soda

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What is volatile and non volatile

Posted by Tisha Malhi 6 years, 7 months ago

CBSE > Class 12 > Chemistry

1 answers

Nishu Sahu 6 years, 7 months ago

Those substances which evaporates eaisly are called volatile. Those substances which do not evaporate easily are called non volatile.

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I want to make an investigatory project for class 12 practical chemistry . Suggest me any topic.????

Posted by Harpreet Kaur 6 years, 7 months ago

CBSE > Class 12 > Chemistry

2 answers

Harpreet Kaur 6 years, 7 months ago

But how to investigate

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Alok Singh 6 years, 7 months ago

Vitamins

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Calculation of density of unit cell

Posted by Bks Sahu 6 years, 7 months ago

CBSE > Class 12 > Chemistry

0 answers

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What is non ideal solution

Posted by Aliya 000 6 years, 7 months ago

CBSE > Class 12 > Chemistry

7 answers

Satyam Krishna 6 years, 7 months ago

A solution which doesn't obey raoult's law at all temperature and concration is called non ideal solution.

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K@Łp@N@ $Øđh!?? 6 years, 7 months ago

The solution that doesn't follow the raults law

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Deepak Jindal 6 years, 7 months ago

Which do not obey raoult's law...???????

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Himam Jani 6 years, 7 months ago

The solution which does not obey raults law,and whose change in volume and change in enthalpy is not equal to zero

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Tapan Pandey 6 years, 7 months ago

Sol. That doesn't follow the roult's law

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Kashish Goyal 6 years, 7 months ago

The sol which doesnot depend on raults law

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Kriti Sharma 6 years, 7 months ago

Which does not follow raults law .??????

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Lyobolic

Posted by Ravi Raj 6 years, 7 months ago

CBSE > Class 12 > Chemistry

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New paper format Of class 12

Posted by Devendra 10 6 years, 7 months ago

CBSE > Class 12 > Chemistry

1 answers

Abhishek Kumar 6 years, 7 months ago

Go to cbse.nic.in

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How to draw 5 carbon parent chain of C13H28

Posted by Nikita Saran 6 years, 7 months ago

CBSE > Class 12 > Chemistry

0 answers

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Potentiometric titrations

Posted by Ramesh Mishra 6 years, 7 months ago

CBSE > Class 12 > Chemistry

2 answers

Deepak Jindal 6 years, 7 months ago

Device which can measure the emf of potential difference

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Ramesh Mishra 6 years, 7 months ago

It is a device in which can measure the emf of potential difference

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Bhav

Posted by Pk Suthar 6 years, 7 months ago

CBSE > Class 12 > Chemistry

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Show that in the first order reaction time required for completing of 99.9% is 10 time of half life of the reaction

Posted by Sabiya Malik 6 years, 7 months ago

CBSE > Class 12 > Chemistry

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Vant's Hoff factor 0.1 m b a n o 3 bracket Me 2 solution is 0.74 find the degree of dissociation

Posted by Bablu Jyani Jyani 6 years, 7 months ago

CBSE > Class 12 > Chemistry

2 answers

Sudarshan Sharma 6 years, 7 months ago

Sorry bro but actually as the vont half factor is less than 1 so association is occurring so degree of association is 39 percent

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Sudarshan Sharma 6 years, 7 months ago

13 percent

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Compare the Osmotic pressure of 0.1 molar urea despotic pressure of 0.01 M KCL will be

Posted by Bablu Jyani Jyani 6 years, 7 months ago

CBSE > Class 12 > Chemistry

1 answers

Sudarshan Sharma 6 years, 7 months ago

Osmotic pressure of urea will be more as osmotic pressure is directly proportional to i*effective molality so for urea i*c = 1*0.1 =0.1 now in kcl molarity is given but generally in solution questions as solution is very dilute to find colligative property then molarity =molarity so for kcl i*c = 0.01*2 = 0.02

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Which colligative property can provide molar mass of protien with greater precision

Posted by Bablu Jyani Jyani 6 years, 7 months ago

CBSE > Class 12 > Chemistry