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Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Chemistry

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Chemistry
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Match the polymers given in Column I with the type of linkage present in them given in Column II.

Column I Column II
(i) Terylene (a) Glycosidic linkage
(ii) Nylon (b) Ester linkage
(iii) Cellulose (c) Phosphodiester linkage
(iv) Protein (d) Amide linkage
v) RNA  
[15] Polymers
Chapter: [15] Polymers
Concept: undefined >> undefined

Match the polymers given in Column I with their repeating units given in Column II.

Column I Column II
(i) Acrilan

(a) \[\begin{array}{cc}
\ce{-(CH2 - CH)\underset{n}{-}}\\
\phantom{....}|\\
\phantom{.......}\ce{C6H5}
\end{array}\]

(ii) Polystyrene (b) \[\begin{array}{cc}
\ce{Cl}\phantom{.......}\\
|\phantom{........}\\
\phantom{}\ce{-(CH2 - C = CH - CH2)\underset{n}{-}}
\end{array}\]
(iii) Neoprene (c) \[\begin{array}{cc}
\phantom{................................}\ce{CN}\\
\phantom{..............................}|\\
\ce{-(CH2 - CH = CH - CH2 - CH2 - CH)\underset{n}{-}}
\end{array}\]
(iv) Novolac (d) \[\begin{array}{cc}
\ce{-(CH2 - CH)\underset{n}{-}}\\
\phantom{.....}|\\
\phantom{.......}\ce{CN}
\end{array}\]
(v) Buna—N (e) 
  (f)  \[\begin{array}{cc}
\ce{-(CH2 - CH)\underset{n}{-}}\\
\phantom{.....}|\\
\phantom{......}\ce{Cl}
\end{array}\]
[15] Polymers
Chapter: [15] Polymers
Concept: undefined >> undefined

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Phenol and formaldehyde undergo condensation to give a polymar (A) which on heating with formaldehyde gives a thermosetting polymer (B). Name the polymers. Write the reactions involved in the formation of (A). What is the structural difference between two polymers?

[15] Polymers
Chapter: [15] Polymers
Concept: undefined >> undefined

Convert the following:

Chloroethane to methanamine.

[6] Haloalkanes and Haloarenes
Chapter: [6] Haloalkanes and Haloarenes
Concept: undefined >> undefined

Given below are two statements labelled as Assertion (A) and Reason (R).

Assertion (A): An ether is more volatile than an alcohol of comparable molecular mass

Reason (R): Ethers are polar in nature.

Select the most appropriate answer from the options given below:

[7] Alcohols, Phenols and Ethers
Chapter: [7] Alcohols, Phenols and Ethers
Concept: undefined >> undefined

Given below are two statements labelled as Assertion (A) and Reason (R).

Assertion (A): Proteins are found to have two different types of secondary structures viz alpha-helix and beta-pleated sheet structure.

Reason (R): The secondary structure of proteins is stabilized by hydrogen bonding.

Select the most appropriate answer from the options given below:

[10] Biomolecules
Chapter: [10] Biomolecules
Concept: undefined >> undefined

An α-helix is a structural feature of ______.

[10] Biomolecules
Chapter: [10] Biomolecules
Concept: undefined >> undefined

Proteins are polymers of ______.

[10] Biomolecules
Chapter: [10] Biomolecules
Concept: undefined >> undefined

Assertion (A): Elevation in boiling point is a colligative property.

Reason (R): The lowering of vapour pressure of solution causes elevation in boiling point.

[1] Solutions
Chapter: [1] Solutions
Concept: undefined >> undefined

Auto-oxidation of chloroform in air and sunlight produces a poisonous gas known as ______.

[6] Haloalkanes and Haloarenes
Chapter: [6] Haloalkanes and Haloarenes
Concept: undefined >> undefined

Assertion (A): Proteins are polymers of α-amino acids connected by a peptide bond.

Reason (R): A tetrapeptide contains 4 amino acids linked by 4 peptide bonds.

[10] Biomolecules
Chapter: [10] Biomolecules
Concept: undefined >> undefined

If the molality of a dilute solution is doubled, the value of the molal elevation constant (Kb) will be ______.

[1] Solutions
Chapter: [1] Solutions
Concept: undefined >> undefined

Calculate the boiling point elevation for a solution prepared by adding 10 g of MgCl2 to 200 g of water, assuming MgCl2 is completely dissociated.

(Kb for Water = 0.512 K kg mol−1, Molar mass MgCl2 = 95 g mol−1)

[1] Solutions
Chapter: [1] Solutions
Concept: undefined >> undefined

Which of the following aqueous solution will have the highest boiling point?

[1] Solutions
Chapter: [1] Solutions
Concept: undefined >> undefined

Write the equation for the following:

Oxidation of chloroform by air and light.

[6] Haloalkanes and Haloarenes
Chapter: [6] Haloalkanes and Haloarenes
Concept: undefined >> undefined

β-pleated sheet structure in proteins refers to ______.

[10] Biomolecules
Chapter: [10] Biomolecules
Concept: undefined >> undefined

A solution of [Ni(H2O)6]2+ is green, but a solution of [Ni(CO)4] is colourless. Explain.
[Atomic number: Ni = 28]

[5] Coordination Compounds
Chapter: [5] Coordination Compounds
Concept: undefined >> undefined

Read the passage carefully and answer the questions that follow.

The lead-acid battery represents the oldest rechargeable battery technology. Lead acid batteries can be found in a wide variety of applications including small-scale power storage such as UPS systems, ignition power sources for automobiles, along with large, grid-scale power systems. The spongy lead act as the anode and lead dioxide as the cathode. Aqueous sulphuric acid is used as an electrolyte. The half-reactions during discharging of lead storage cells are:

Anode: \[\ce{Pb(s) + SO^{2-}_4 (aq) -> PbSO4 (s) + 2e-}\]

Cathode: \[\ce{PbO (s) + 4H+ (aq) + SO^{2-}_4 (aq) + 2e- -> PbSO(s) + 2 H2O}\]

There is no safe way of disposal and these batteries end - up in landfills. Lead and sulphuric acid are extremely hazardous and pollute soil, water as well as air. Irrespective of the environmental challenges it poses, lead-acid batteries have remained an important source of energy.

Designing green and sustainable battery systems as alternatives to conventional means remains relevant. Fuel cells are seen as the future source of energy. Hydrogen is considered a green fuel. Problem with fuel cells at present is the storage of hydrogen. Currently, ammonia and methanol are being used as a source of hydrogen for fuel cell. These are obtained industrially, so add to the environmental issues.

If the problem of storage of hydrogen is overcome, is it still a “green fuel?” Despite being the most abundant element in the Universe, hydrogen does not exist on its own so needs to be extracted from the water using electrolysis or separated from carbon fossil fuels. Both of these processes require a significant amount of energy which is currently more than that gained from the hydrogen itself. In addition, this extraction typically requires the use of fossil fuels. More research is being conducted in this field to solve these problems. Despite the problem of no good means to extract Hydrogen, it is a uniquely abundant and renewable source of energy, perfect for our future zero-carbon needs.

Answer the following questions:

  1. How many coulombs have been transferred from anode to cathode in order to consume one mole of sulphuric acid during the discharging of lead storage cell?
  2. How much work can be extracted by using lead storage cell if each cell delivers about 2.0 V of voltage? (1 F = 96500 C)
  3. Do you agree with the statement – “Hydrogen is a green fuel.” Give your comments for and against this statement and justify your views.

OR

Imagine you are a member of an agency funding scientific research. Which of the following projects will you fund and why?

  1. safe recycling of lead batteries
  2. extraction of hydrogen
[2] Electrochemistry
Chapter: [2] Electrochemistry
Concept: undefined >> undefined

Give the IUPAC name of the following compound:

\[\ce{(CCl3)3CCl}\]

[6] Haloalkanes and Haloarenes
Chapter: [6] Haloalkanes and Haloarenes
Concept: undefined >> undefined

Name and draw the structure of the repeating unit in natural rubber.

[15] Polymers
Chapter: [15] Polymers
Concept: undefined >> undefined
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