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**Previous Year Questions - Structure of Atom, Class 11 (IIT - JEE Advanced)**

**Q 1. With what velocity should an α-particle travel towards the nucleus of a Cu atom so as to arrive at a distance 10 ^{-13} m. [JEE 1997]**

**Ans. ** 6.3×10^{8} m/s

**Q 2. A compound of Vanadium has magnetic moment of 1.73 BM work out electronic configuration of Vanadium Ion in the compound. [JEE 1997]**

**Ans. ** _{23}V^{+2 }: [Ar] 3d^{1}

**Q 3. Calculate the energy required to excite one litre of hydrogen gas at 1 atm and 298 K to the first excited state of atomic hydrogen. The energy for the dissociation of H - H is 436 kJ mol ^{-1}. **

**Ans. ** 98.2 kJ

**Q4. The Schrodinger wave equation for hydrogen atom is**

**Where a _{0} is Bohr's radius. If the radial node is 2s be at r_{0}, then find r_{0} in term of a_{0}. [JEE 2004]**

**Ans. **2a_{0}

**Q 5. A ball of mass 100 g is moving with 100 m/s. Find its wavelength [JEE 2004]**

**Ans. ** 6.6 × 10^{-35} s^{-1}

**Q 6. Find the velocity (m/s) of electron in first Bohr's orbit of radius a _{0}. Also find the de Broglie's wavelength (in m). Find the orbital angular momentum of 2p orbital of hydrogen atom in units of **

**Ans. ** 3.34 × 10^{-10} m

**Q 7. The maximum number of electrons that can have principal quantum number, n = 3, and spin quantum number, m _{s} = – 1/2, is: [JEE 2011]**

**Ans. ** 0009

**Q 8. The work function (φ) of some metals is listed below. The number of metals which will show photoelectric effect when light of 300 nm wavelength falls on the metal is [JEE 2011]**

**Ans. ** 0004

**Q 9. The work functions of Silver and Sodium are 4.6 and 2.3 eV, respectively. The ratio of the slope of the stopping potential versus frequency plot for Silver to that of Sodium is [JEE 2013]**

**Ans. ** 1

**Q 10. The atomic masses of He and Ne are 4 and 20 a.m.u. respectively. The value of the de Broglie wavelength of He gas at -73 ºC is "M" times that of the de Broglie wavelength of Ne at 727 ºC. M is [JEE 2013]**

**Ans. ** 0005

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**Previous Year Questions - Organic Chemistry, Class 11 (IIT - JEE Advanced)**

**Q 1. Out of anhydrous AlCl3 and hydrous AlCl3 which is more soluble in diethyleither ? Explain with reason. [JEE-2003]**

**Sol. **Anhydroush AlCl_{3} is more soluble in diethyl ether

**Q 2. Match K _{a} values with suitable acid: [JEE-2003]**

**K _{a} (i) 3.3 × 10^{-5} (ii) 4.2 × 10^{-5} (iii) 6.3 × 10^{-5} (iv) 6.4 × 10^{-5} (v) 30.6 × 10^{-5}**

**Ans.** (i) d

(ii) b

(iii) a

(iv) c

(v) e

**Q 3. Give resonating structures of following compound: **

** ** **[JEE-2003]**

**Ans. **

**Q 4. Which of the following is more acidic and why ?**

** [JEE-2004]**

**Ans.**

** **

**Q 5. Predict whether the following molecules are iso structural or not. Justify your answer. [JEE-2005] (i) NMe(3 **

**(ii) N(SiMe _{3})_{3}**

**Ans.**

** **

Given componds are not isostrucutral

Delocalised of l.p. of nitrogen in vacant d-orbital of silicon makes compound planar.

**Q 6. The total number of basic group in the following form of lysine is [JEE-2010]**

**Ans. 2**

**Q 7. The total number of contrubting structure showing hyperconjugation (involving C-H bonds) for the following carbocation is ** **[JEE-2011]**

**Ans. 6**

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**Previous Year Questions - States of Matter - Gases and Liquids, Class 11 (IIT - JEE Advanced)**

**Q. 1 The density of the vapour of a substance at 1 atm pressure and 500 K is 0.36 Kg m ^{-3}. The vapour effuses through a small hole at a rate of 1.33 times faster than oxygen under the same condition. [JEE 2002]**

**(a) Determine**

(i)** mol. wt.;**

(ii)** molar volume;**

(iii)** compression factor (z) of the vapour and**

(iv)** which forces among the gas molecules are dominating, the attractive or the repulsive**

**(b) If the vapour behaves ideally at 1000K , determine the average translational K.E. of a molecule.**

**Ans. **

(a)

(i) 18.1 g/mol ,

(ii) 50.25 L mol^{–1} ,

(iii) 1.224 ,

(iv) repulsive,

(b) 2.07 × 10^{–20} J

**Q 2. The average velocity of gas molecules is 400 m/sec. Calculate its (rms) velocity at the same temperature. ** ** [JEE 2003]**

**Ans. **434.17 m/sec

**Q 3. C _{V} value of He is always 3R/2 but C_{V} value of H_{2} is 3R/2 at low temperature and 5R/2 at moderate temperature and more than 5R/2 at higher temperature explain in two to three lines. [JEE 2003]**

**Ans. **Since H_{2} is diatomic and He is monoatomic degree of freedom for mono is 3 and only translational

but for diatomic, vibrational and rotational are also to be considered

**Q 4. For a real gas obeying van der Waal's equation a graph is plotted between PVm (y-axis) and P(x-axis) where V _{m} is molar volume. Find y-intercept of the graph. [JEE 2004]**

**Ans. **RT

**Q 5. The atomic masses of He and Ne are 4 and 20 a.m.u, respectively. The value of the de Broglie wavelength of He gas at -73°C is “M” times that of the de Broglie wavelength of Ne 727°C. M is: [JEE(ADVANCED)-2013, 4/120]**

**Ans. **5

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**Previous Year Questions - Thermochemistry, Class 11 (IIT - JEE Advanced)**

**Q 1. Estimate the average S - F bond energy in SF6. The ** ** values of SF _{6}(g), S(g), and F(g) are -1100, 275 and 80 kJ/mol respectively. [JEE 1999]**

**Ans. **309.6 kJ/mol

**Q 2. Diborane is potential rocket fuel which undergoes combustion according to the reaction, B _{2}H_{6}(g) + 3O_{2}(g) → B_{2}O_{3}(s) + 3H_{2}O (g) From the following data, calculate the enthalpy change for the combustion of diborane :**

**2B(s) + ** **O _{2}(g) → B_{2}O_{3}(s) ; ΔH = –1273 kJ**

H_{2}(g) +

H

2B(s) + 3H

**Ans. **-2035 kJ mol^{-1}

**Q 3. In a constant volume calorimeter, 3.5 g of a gas with molecular weight 28 was burnt in excess oxygen at 298.0 K. The temperature of the calorimeter was found to increase from 298.0 K to 298.43 K due to the combustion process. Given that the heat capacity of the calorimeter is 2.5 kJ K ^{-1}, the numerical value for the enthalpy of combustion of the gas in KJ mol^{–1} is [JEE 2009]**

**Ans. 9**

**Previous Year Questions - Isomerism, Class 11 (IIT - JEE Advanced)**

**Q 1**

**(i) **

**whre µ _{i} is the dipole moment of a stable conformer of the molcule, Z - CH_{2} - CH_{2 }- Z and x_{i} is the mole fraction of the stable conformer.**

**Given : µ _{obs} = 1.0 D and x (Anti) = 0.82**

**Draw all the stable conformers of Z - CH _{2} - CH_{2 }- Z and calculate the value of µ_{(Gauche)}.**

**(ii) Draw the stable conformer of Y - CHD - CHD - Y (meso form), when Y = CH _{3} (rotation about C_{2} - C_{3}) and Y = OH (rotation about C_{1} - C_{2}) in Newmann projection. [JEE 2005]**

**Ans. **

(ii) Anti form when Y = CH_{3} & Gauche when Y = -OH

**Q 2. The total number of cyclic structural as well as stereo isomers possible for compound with the molecular formular C _{5}H_{10} is [JEE 2009] **

**Ans. **7

**Q 3. The total number of cyclic isomers possible for a hydrocarbon with the molecular formula C _{4}H_{6} is [JEE 2010]**

**Ans. **5

**Previous Year Questions - Chemical Equilibrium, Class 11 (IIT - JEE Advanced)**

**Q 1. The degree of dissociation is 0.4 at 400K & 1.0 atm for the gasoeus reaction PCl _{5 } PCl_{3}+ Cl_{2}(g). Assuming ideal behaviour of all gases. Calculate the density of equilibrium mixture at 400K & 1.0 atm pressure. [JEE 1999]**

**Ans. **4.54 g dm^{–3}

**Q 2. When 3.06 g of solid NH _{4}HS is introduced into a two litre evacuated flask at 27°C, 30% of the solid decomposes into gaseous ammonia and hydrogen sulphide. [JEE 2000]**

**(i) Calculate K _{C} & K_{P} for the reaction at 27°C.**

**(ii) What would happen to the equilibrium when more solid NH _{4}HS is introduced into the flask ?**

**Ans. **(i) Kc = 8.1 × 10^{–5} mol^{2} L^{2} ; Kp = 4.91 × 10^{–2} atm^{2 }

(ii) No effect ;

**Previous Year Questions - Ionic Equilibrium, Class 11 (IIT - JEE Advanced)**

**Q 1. What will be the resultant pH when 200 ml aqueous solution of HCl (pH = 2.0) is mixed with 300 ml of an aqueous solution of NaOH (pH=12.0)? [JEE 1998]**

**Ans. ** pH=11.3010

**Q 2. The solubility of Pb(OH) _{2} in water is 6.7 × 10^{-6} M. Calculate the solubility of Pb(OH)_{2} in a buffer solution of pH= 8. [JEE '1999]**

**Ans. ** s = 1.203×10^{-3} M

**Q 3. 500 ml of 0.2 M aqueous solution of acetic acid is mixed with 500 mL of 0.2 M HCl at 25°C**

**(a) Calculate the degree of dissociation of acetic acid in the resulting solution and pH of the solution.**

**(b) If 6 g of NaOH is added to the above solution, determine final pH. Assume there is no change in volume on mixing. K _{a} of acetic acid is 1.75 × 10^{-5} M. [JEE 2002]**

**Ans. ** ** **(a) 0.0175%

(b) 4.757

** **

**Q 4. Will the pH of water be same at 4°C and 25°C ? Explain. [JEE 2003]**

**Ans. **No it will be > 7

**Q 5. 0.1 M of HA is titrated with 0.1 M NaOH, calculate the pH at end point. Given Ka(HA) = 5 × 10 ^{-6} and a << 1. [JEE 2003]**

**Ans. ** ** ** pH = 9

**Q 6. The dissociation constant of a substituted benzoic acid at 25ºC is 1.0 × 10 ^{-4}. The pH of a 0.01 M solution of its sodium salt is : [JEE 2009]**

**Ans. ** pH = 8

**Q 7. The total number of diprotic acids among the following is [IIT-2010]**

**H _{3}PO_{4} H_{2}SO_{4} H_{3}PO_{3 } H_{2}CO_{3 }H_{2}S_{2}O_{7}**

**H _{3}BO_{3 }H_{3}PO_{2 }H_{2}CrO_{4 }H_{2}SO_{3}**

**Ans. **6** **

**Q 8. In 1 L saturated solution AgCl [K _{sp}(AgCl) = 1.6 × 10^{-10}], 0.1 mol of CuCl [K_{sp}(CuCl) = 1.0 × 10^{-6}] is added. The resultant concentration of Ag^{+} in the solution is 1.6 × 10^{-x}. The value of "x" is **

**[JEE 2011]**

**Ans. **7

**Previous Year Questions - Stoichiometry, Class 11 (IIT - JEE Advanced)**

**Q 1. How many moles of e ^{_} weigh one Kg**

**Ans . **

**Q 2. Calculate the molarity of pure water using its density to be 1000 kg m ^{-3}. [JEE' 2003] **

**Ans. **55.5 mol L^{-1}

**Q 3. One gm of charcoal absorbs 100 ml 0.5 M CH _{3}COOH to form a monolayer, and there by the molarity of CH_{3}COOH reduces to 0.49. Calculate the surface area of the charcoal adsorbed by each molecule of acetic acid. Surface area of charcoal = 3.01 × 10^{2} m^{2}/gm.**

**Ans. **5 × 10^{-19} m^{2}

**Q 4. Calculate the amount of Calcium oxide required when it reacts with 852 gm of P _{4}O_{10}. [JEE 2005] **

**Ans. **1008 gm

**Q 5. 20% surface sites have adsorbed N _{2}. On heating N_{2} gas evolved from sites and were collected at 0.001 atm and 298 K in a container or volume is 2.46 cm^{3}. Density of surface sites is 6.023 × 10^{14}/cm^{2} and surface area is 1000 cm^{2}, find out the no. of surface sites occupied per molecule of N_{2}.**

**Ans. **0002

**Q 6. Dissolving 120 g of urea (mol. wt. 60) in 1000 g of water gave a solution of density 1.15 g/mL. The molarity of the solution is: [JEE 2011]**

**Ans. 2.05 M**

**Q 7. Reaction of Br _{2} with Na_{2}CO_{3} in aqueous solution gives sodium bromide and sodium bromate with evolution of CO_{2} gas. The number of sodium bromide molecules involved in the balanced chemical equation is: [JEE 2011] **

**Ans. **0005

**Q 8. A decapeptide (Mol. wt. 796) on complete hydrolysis gives glycine (Mol. Wt. 75), alanine and phenylalanine. Glycine contributes 47.0% to the total weight tto the hydrolysed products. The number of glycine units present in the decapeptideis : [JEE 2011]**

**Ans. **0006

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