DAV PUBLIC SCHOOL, POWER GRID CAMPUS, BIHAR SHARIF (NALANDA)

Home assignment for summer vacation (2018-2019)

Class: XII

Sub: physics

  1. Write coulomb’s law in vectors form. What is the importance of expressing it in vector form?
  2. Define electric field intensity and derive an expression for electric field at a point on axial line of a dipole also determine its direction.
  3. What is an electricdipole? Derive an expression for torque acting on an dipole

When held in a uniform E.F, hence define dipole moment.

4. A thin conducting spherical shell of radius“R”has charge “Q” spread uniformly over its surface. UsingGauss’s law, derive an expression for electric field at a point outside the shell. Draw a graph of electric field E (r) with distance r from the centre of the shell for 0 r .

5. State Gauss theorem in electrostatics using this theorem derive an expression for the electric field intensity due to an infinitely long straight wire of linear charge density “λ Cm-1

6. A charge Q is uniformly distributed within a sphere of radius R . Find The electric field due to this charge distribution at a point distant r from the centre of the sphere where

(a) o < r < R (ii) r> R.

7. Derive an expression for the potential energy of an electric dipole of dipole moment P in an electric field E

8. (a) Obtain the expression for the potential due to a point charge.

(b) use the above expression to show that the potential , due to an electic dipole (length 2a) , varies as the inverse square of the distance r.

9. Sketch equipotential surface for

(a) a +ve point charge

(b) a –ve point charge

(c) two equal and opposite charges separated by a small distance.

10. An infinite line charge produce an electric field of 9 X 104 NC-1 at a distance of 2 cm .Calculate the linear charge density.

11. Two large thin metal plates are parallel and close to each other on their inner faces. The plates have surface charge densities of opposite signs and of magnitude

17X 1022 cm-2. What is E(a) to the left of the plates.

(b)To the right of the plates and (c) between the plates.

12. A spherical rubber balloon, carries a charge that is uniformly distributed over its surface. As the balloon is blown up, how does E vary for points?

(i) Inside the balloon

(ii) On the surface of the balloon

(iii) Outside the balloon?

13. Two thin concentric and coplanar spherical shells, of radius a and b (b>a) carry charge q and Q respectively, Find the magnitude of the electric field at a point distance x from their common centre for

(i) o < x<a (ii)a<x<b(iii) b < x <

14. Two charges 5X 10-8 C and -3X10-8 C are located 16 cm apart .At what point on the line joining the two charges is the eclectic potential zero? Take the potential at infinity to be zero.

Sub: Chemistry

  1. What is denatured alcohol?
  2. Write the IUPAC names of the following:
  1. Ethylidene chloride
  2. Ethyline dichloride
  1. Give reason for the following statements
  1. Phenol do not give protonation reaction readily.
  2. Methanol is less acidic than phenol
  1. Explain a process in which a biocatalyst is used in the industrial preparation of a compound.
  2. Assign reason for the following:
  1. To Kolbe’s reaction instead of phenol phenoxide ion treated with CO2
  2. Although phenol is an acid, yet it does not react with sodium bi-carbonate.
  1. Convert the following
  1. Phenol to aspirin
  2. Salicylic acid to oil of winter green
  3. Ethanol to But-2-enoic acid
  1. Account the following:
  1. O – nitrophenol has lower boiling point than p – nitrophenol
  2. Chlorobutane has higher boiling point than 2-methyl 2-chlorobutane.
  1. A. Write the structure of 2-(2-bromophenyl)butane

B. Haloalkanereact with KCN to form alkyl cyanides as the main product while AgCN form iso-cyanides as the main product. Explain

  1. Name the reagent which are used in the following conversions:
  1. A primary alcohol to an aldehydes
  2. Butane – 2-one to butan-2-ol
  3. Phenol to 2, 4, 6 tribromophenol
  1. Haloarene are much less reactive than Haloalkane towards nucleophilic substitution reactions, why? Give reasons.
  2. Describe the following;
  1. Swarts reaction
  2. Finkelstein reaction
  3. Wurtz reaction
  1. A. How is ethanol obtained from 2 – butane

B. Write the IUPAC names of the following compound

C. Out of 2-choro ethanol and ethanol which is more acidic and why?

  1. A. Show how the following alcohol is prepared by the reaction of Suitable Grignard reagent with methanol

B. Preparation of ethers by acid dehydration of or tertiary alcohols is not suitable method. Give reason

  1. How do you convert the following
  1. Phenol to anisole
  2. Propane -2-ol to 2 methyl propan-2-ol
  3. Aniline to phenol
  1. Give reasons
  1. n butyl bromide has higher boiling point than t-butyl bromide
  2. Racemic mixture is optically inactive
  3. The presence of nitro group (-NO2) at O/P position increases the reactivity of haloarenes.
  1. How can ethyl bromide be obtained from ethene? How does it react with the following reagents?
  1. Aq. Kottb. No metal c. NaCNd. CH3CH2Ona
  1. A. Describe sandmeyer reaction talking a suitable example.

B. Discuss briefly the mechanisms of SN’ reactions.

  1. Explain the following with an example
  1. Kolbe’s reaction
  2. Reiner – tiemann reaction
  3. Williamson ether synthesis
  4. Unsymmetrical ether
  1. Write the mechanism of acid dehydration of ethanol to yield ethene.
  2. Give two reactions that show the acidic nature of phenol. Compare aciding of phenol with that of ethanol.
  3. Why is coordination number 12 not found in ionic crystal?
  4. A. What is meant by octahedral voids?

B. A solid is formed by two elements P and Q the elements Q forms cubic clone packing and atoms of P occupy two third of octahedral voids evaluate the formulae of the compound.

  1. How would you account for the following:
  1. Frankel defects are not found in the alkali metal halide.
  2. Schottky defect lower the density of related solids
  3. What happens when ferromagnetic Fe3O4 is heated at 850 K and why/
  1. A cubic solid is made up of two elements P and Q. Atom Q is product at corner at the cube and atom P at the body centre what is the formula of the compound? What are the coordination numbers of P and Q?
  2. Calculate the distance between Na+ and Cl- ion in NaCl crystals, if its density is 2.165 gcm-1
  3. Assign reason for the following
  1. Phosphorous doped silicon is semiconductor
  2. Some of the very old glass objects appear.
  1. Explain, why a solution of chloroform and acetone shows negative deviation from Raoull’s Law?
  2. Calculate the depression in the freezing point of water when 10g of CH3CH2ClCOOH is added to 250 g of water? (degree of dissociation ≤ 0.065, Kf = 1.86 K KgMol-1)
  3. Henry’s low constant for CO2 dissolving in water is 1.67 x 108 pa at 298 K. calculate the quantity of CO2 in 1L of soda water when packed under 2.5 atm CO2 pressure at 298 K.
  4. Give reason for the following
  1. At higher altitudes people develop a medical condition called anoxia resulting in physical and mental weakness including hallucination.
  2. When mercuric iodide is added to an aqueous solution of KI the freezing point is raised?
  1. A. Why is vapour pressure of a solution of glucose in water lower than that of water?

B. Calculate the molality of 25 g ethanoic acid (CH3COOH) in 75g of benzene.

  1. A. In a compound nitrogen atom (N) makes cubic wise packed lattice and atoms of (N) occupy one third of the tetrahedral voids present derive the formula of the compound formed by metal (N) and n on-metal (N) (nitrogen).

B. Calculate the packing efficiency of a metal crystal for body centered cubic (bcc) structure.

  1. Calculate the freezing point of a solution containing 50.0 g of ethylene glycol (Molecular weight = 62) dissolved in 600 g of water. (Kf for water = 1.86 K kg mo-1)
  2. Explain the painful condition in scuba drivers known as bends with the help of Henry’s Law?
  3. Niobium crystalline in body centered cubic structure. If density is 8.55gcm-3 calculate atomic radius of niobium using its atomic radius of niobium using its atomic mass 93 u
  4. Give reason
  1. FeO(s) is not formed in stoichiometric composition.
  2. The electrical conductivity of semiconductors increases with rise in temperature.
  1. Find the amount of calcium chloride dissolved in 2.5 l of water such that its osmotic pressure is 0.75 atm at 270 C ( given that vant Hoff factor of CaCl2 = 2.47
  2. Calculate the packing efficiency of a metal crystal for a simple cubic lattice.
  3. Define the following terms
  1. Colligative properties
  2. Molality (w)
  1. A. Gas (A) is more soluble in water than gas (B, at the same temperature which one of the two gases will have the higher value of Kh( Henry’s Constant) and why?

B. In non-ideal solution what type of deviation shows the formation of maximum boiling azeotropes?

  1. Complete all exercise (NCERT) question answer of Lesson – 1,2 from organic and 1,2 from physical chemistry
  1. Solid state
  2. Solution
  3. Haloalkane and Haloarene
  4. Alcohol, phenol and ether.

Sub: Biology

  1. Solve current unit -6.
  2. Solve NCERT exemplar.
  3. Complete Practical copy.

Sub: English

  • Write review of a movie seeing with your mother/father.
  • Write review of novel of your choice.
  • Write short notes on the following

(i)Superstation v/s science.

(ii)Communalisation v/s National integration

(iii)Feminism v/s chauvinism

(iv)Effect of cinema on society

(v)Untouchability

Sub: IP

1.Write any 20 java programming code with their output.

2.Create a table in RDBMS & write any 20 query regarding the table.

3.What is communication channel & how many types.Write also Coaxial, twistedoptical cable

4.Define the all networking devices.

5.Write shorts notes:-

i) Network security

ii) Firewall

iii) Dos

IV) Hacker & Cracker

V) Pc Intrusion

6.Learn regarding open source software, Licensingsoftware, freeware software, customize software.

Sub: Maths

  1. Solve all the questions from NCERT Text Book from the following chapters.

(a)Relation , Function(ii) Matrices and Determinant(iii) Inverse Trigonometric