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

A solution of sucrose (Molar mass 342 a mol -1 ) is prepared by dissolving 68.4 a in 1000g of
water. What is the
i. Vapour pressure of the solution at 293k.
ii. Osmotic pressure at 293k.
iii. Boiling point of the solution.
iv. Freezing point of the solution.
The vapour pressure of the water at 293k is 0.023atm. k b =0.52k kg mol -1 & k f = 1,86k
kg mol -1 . Assume the solution to behave ideally.

Posted by Aishwarya S 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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how to learn periodic table

Posted by Paras Singh 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Shivam Jha 6 years, 9 months ago

By regular revision

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The conductivity of a 0.01M solution of acetic acid at 298k is 1.65×10^-4 S cm^-1. Calculate molar conductivity (^m) of the solution.

Posted by Rajam 1969 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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A current of 1.50A was passed through an electrolytic cell containing AgNO3 solution with inert electrodes. The weight of silver deposited was 1.50g. How long did the current flow? (Molar mass of Ag=108g mol^-1,1F=96500 c mol^-1).

Posted by Rajam 1969 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Sanskriti S 6 years, 9 months ago

using W=ZQ=Zit ==> t=W/Zi = 1.50*96500/(108*1.50), (where Z=eq. wt. /96500)

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Out of chlorobenzene and benzyl chloride, which one gets easily hydrolysed by aqueous NaOH and why?

Posted by Rajam 1969 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Sanskriti S 6 years, 9 months ago

benzyl chloride ; in chlorobenzene C-Cl bond acquires double bond character due to resonance, so doesn't easily undergo nucleophilic subst. reacn

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Modern adsorption theory of catalysis

Posted by Raksha Shrivastava 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Modern adsorption theory of catal

Posted by Raksha Shrivastava 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Why is n2 very inert

Posted by Sapam Tony 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Sanskriti S 6 years, 9 months ago

because of triple bond, it has high bond energy dissociation nd very less reactivity

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A solution is obtain by mixing of 25% of 40% solution by mass. Calculate mass percentage

Posted by Ankit Saini 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Aishwarya S 6 years, 9 months ago

According to question,

100g of 25% solution contains solute = (100 x 25) / 100 = 25g

&

100g of 40% solution contains solute = (100 x 40) / 100 = 40g

Total solute = 25 + 40 = 65g

As given in the question, total solution =100 + 100 = 200g

Percentage of solute in the final solution = (65 x100) / 200 = 32.5%

Percentage of water in the final solution = 100 - 32.5 = 67.5%

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Is SiBr4 or SiBr2 correct?

Posted by Govind Vijay 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Give application of n- type and p- type semiconductors

Posted by Vikash Rajput 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Define half-life

Posted by Vaibhav Thakur 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Yogita Ingle 6 years, 9 months ago

The half-life of a radioactive substance, as the name suggests is the time taken for half its radioactive atoms to decay. Half-life of a radioactive substance is defined as the time during which the number of atoms of the substance are reduced to half their original value. It is not generally possible to predict when a particular atom will decay or not. However, with the help of half-life it becomes possible to calculate the time taken by half of the nuclei of radioactive substance to decay. There may be several definitions of half-life, but they basically imply the same thing.

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What is the number of photon of light with wavelength of a 4000 that provide 1 j energy?

Posted by Nitesh Prajapati 6 years, 9 months ago

CBSE > Class 12 > Chemistry

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Asif Muhammad 6 years, 9 months ago

N/t=energy given / (hc/Lambda) N-no. Of photon T - time period H - planks constant

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What will be the best time for me to revise my chemistry syllabus amidst of the exams..... As it seems that a very less time is left from now onwards?

Posted by Ashutosh Sahu 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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What is crystal

Posted by Diljot Bhinder 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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Write down the reactions take place in different zones in blast furnance during extration of iron

Posted by Yaiskul Saikhom 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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What is lanthoid contraction

Posted by Prabhat Roy 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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Yogita Ingle 6 years, 10 months ago

Lanthanide Contraction: The steady decrease in the size of lanthanide ions (M³⁺) with the increase in atomic no. is called lanthanide contraction.

Causes:As we move down the group from left to right in a lanthanide series, the atomic no. increases and for every proton in the nucleus the extra electron goes to 4f orbital. The 4f orbital is too diffused to shield the nucleus effectively, thus there is a gradual increase in the effective nuclear charge experienced by the outer electrons. Consequently , the attraction of the nucleus for the electrons in the outermost shell increases with the increase of atomic number, thus size decreases.

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Ozone gas is used to recover the colour of blackened lead painting?Account.

Posted by Nandini Lingam 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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What is cleavage property

Posted by Ranjeet Singh 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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Yogita Ingle 6 years, 10 months ago

Cleavage means to cut anything in a two or more significant parts, so it is a property which makes the solids cuttable or breakable in simple pieces.A crystalline solid gives similar structures after cleavage while the amorphous solids do not have any planned structure so they give irregular or insignificant pieces after cleavage. So, the property of ideal cleavage is not shown by amorphous solid.

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What are carbohydrates? How are they classified?

Posted by M Maithonbui 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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Hardy schzule rule

Posted by Satveer Sidhu 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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Jasmeet Singh 6 years, 10 months ago

Greater is the charge on oppositely charged ion higher is the coagulating power.

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Pooja Bhatia 6 years, 10 months ago

The greater the valency of the flocculating ion, the greater will be its coagulating power.

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An element of atomic mass 98.5 g/mol occurs in fcc structure . If it's unit cell edge length is 550pm and it's density is 5.22 g/cm-3 , what will be the value of avagardro number ?

Posted by Jerishker Manoharan 6 years, 10 months ago

CBSE > Class 12 > Chemistry

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Pooja Bhatia 6 years, 10 months ago

Z=4{FCC} , Mw=98.5, A= 550pm=5.5 × 10-8cm, density = 5.22 g/cc............. Using, Density = (Z×Mw)/(a^3×N)....... Calcutating value of N: 4.5366×10^23

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Complete the following chemical reaction equations : I2 + HNO3(cons.)----------? HgCl2 +PH3------------?

Posted by Sahir Khan 6 years, 10 months ago

CBSE > Class 12 > Chemistry