Practice Questions

Q30.An audio signal consists of two distinct sounds: one a human speech signal in the frequency band of 200 Hz to 2700 Hz, while the other is a high frequency music signal in the frequency band of 10200 Hz to 15200 Hz. The ratio of the AM signal band width required to send both the signals together to the AM signal band width required to send just the human speech is: JEE Main 2016 (09 Apr Online) JEE Main Previous Year Paper (1) 3 (2) 5 (3) 6 (4) 2

Q30.A modulated signal Cm(t) has the form Cm(t) = 30 sin 300πt + 10(cos 200πt −cos 400πt). The carrier frequency f ′c the modulating frequency(message frequency) fω and the modulation index μ are respectively given by : (1) fc = 200 Hz; fm = 50 Hz ; μ = 21 (2) fc = 150 Hz; fm = 50 Hz ; μ = 32 (3) fc = 150 Hz; fm = 30 Hz ; μ = 13 (4) fc = 200 Hz; fm = 30 Hz ; μ = 21

Q30.A screw gauge with a pitch of 0.5 mm and a circular scale with 50 divisions is used to measure the thickness of a thin sheet of aluminium. Before starting the measurement, it is found that when the two jaws of the screw gauge are brought in contact, the 45th division coincides with the main scale line and that the zero of the main scale is barely visible. What is the thickness of the sheet if the main scale reading is 0 .5 mm and the 25th division coincides with the main scale line? (1) 0.70 mm (2) 0.50 mm (3) 0.75 mm (4) 0.80 mm JEE Main 2016 (03 Apr) JEE Main Previous Year Paper

Q31.At 300 K and 1 atm, 15 mL of a gaseous hydrocarbon requires 375 mL air containing 20% O2 by volume, for complete combustion. After combustion, the gases occupy 345 mL. Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is: (Assume complete combustion of reactant) (1) C4H8 (2) C4H10 (3) C3H6 (4) C3H8

Q32.The amount of arsenic pentasulphide that can be obtained when 35. 5 g arsenic acid is treated with excess H2S in the presence of conc. HCl (assuming 100% conversion) is (1) 0. 25 mol (2) 0. 50 mol (3) 0. 333 mol (4) 0. 125 mol

Q32.A stream of electrons from a heat filament was passed between two charge plates kept at a potential difference V esu. If e and m are charge and mass of an electron, respectively, then the value of hλ (where λ is wavelength associated with the electron wave) is given by: (1) √meV (2) √2 meV (3) me V (4) 2 me V

Q32.The following statements concern elements in the periodic table. Which of the following is true? (1) For group 15 elements, the stability of +5 (2) Elements of group 16 have lower ionization oxidation state increases down the group. enthalpy values compared to those of group 15 in the corresponding periods. (3) The group 13 elements are all metals. (4) All the elements in group 17 are gases.

Q33.The bond angle H-X-H is the greatest in the compound : JEE Main 2016 (10 Apr Online) JEE Main Previous Year Paper (1) PH3 (2) CH4 (3) NH3 (4) H2O

Q34.The species in which the N atom is a state of sp hybridization is: (1) NO−3 (2) NO2 (3) NO+2 (4) NO−2

Q34.Initially, the root-mean-square (RMS) velocity of N2 molecules at certain temperature is u. If this temperature is doubled and all the nitrogen molecules dissociate into nitrogen atoms, then the new RMS velocity will be: (1) 2 u (2) 14 u (3) 4 u (4) u/2

Q35.If 100 mole of H2O2 decompose at 1 bar and 300 K, the work is done ( kJ) by one mole of O2(g) as it expands against 1 bar pressure is: 2H2O2(l) ⇌2H2O(l) + O2(g) (R = 8 .3 J K−1 mol−1) (1) 124. 50 (2) 249. 00 (3) 498. 00 (4) 62. 25

Q35.At very high pressures, the compressibility factor of one mole of a gas is given by: (1) 1 + RTPb (2) RTPb (3) 1 −PbRT (4) 1 − (VRT)b

Q35.Two closed bulbs of equal volume (V) containing an ideal gas initially at pressure pi and temperature T1 are connected through a narrow tube of negligible volume, as shown in the figure below. The temperature of one of the bulbs is then raised to T2. The final pressure Pf is: 2pi (1) 2pi( T1+T2T2 ) (2) T1T2 ( T1+T2 ) (3) pi ( T1+T2T1T2 ) (4) 2pi( T1+T2T1 )

Q37.The volume of 0.1 M strong dibasic acid sufficient to neutralize 1g of a base that furnishes 0.04 mole of OH− in aqueous solution is : (1) 400 mL (2) 600 mL (3) 200 mL (4) 800 mL

Q37.For the reaction, A(g) + B(g) →C(g) + D(g), Δ Ho and ΔSo are, respectively, −29.8 kJ mol−1 and −0.100 kJ K−1 mol−1 at 298 K. The equilibrium constant for the reaction at 298 k is: (1) 1.0 × 10−10 (2) 10 (3) 1 (4) 1.0 × 1010

Q37.The equilibrium constant at 298 K for a reaction A + B ⇌C + D is 100. If the initial concentration of all the four species were 1 M each, then the equilibrium concentration of D (in mol L−1 ) will be: (1) 1. 818 (2) 1. 182 (3) 0. 182 (4) 0. 818

Q38.Which of the following statements about water is FALSE? JEE Main 2016 (03 Apr) JEE Main Previous Year Paper (1) There is extensive intramolecular hydrogen (2) Ice formed by heavy water sinks in normal water. bonding in the condensed phase. (3) Water is oxidized to oxygen during (4) Water can act both as an acid and as a base photosynthesis

Q38.A reaction at 1 bar is non-spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following: (1) ΔH is negative while ΔS is positive (2) Both ΔH and ΔS are negative (3) ΔH is positive while ΔS is negative (4) Both ΔH and ΔS are positive

Q39.Identify the incorrect statement regarding heavy water: (1) It reacts with SO3 to form deuterated sulphuric (2) It is used as a coolant in nuclear reactors. acid (D2SO4) . (3) It reacts with CaC2 to produce C2D2 and (4) It reacts with Al4C3 to produce CD4 and Ca(OD)2 . Al(OD)3 . JEE Main 2016 (09 Apr Online) JEE Main Previous Year Paper

Q39.Identify the reaction which does not liberate hydrogen (1) Reaction of lithium hydride with B2H6 . (2) Electrolysis of acidified water using Pt electrodes. (3) Reaction of zinc with aqueous alkali. (4) Allowing a solution of sodium in liquid ammonia to stand.

Q40.The absolute configuration of is: (1) (2S, 3S) (2) (2R, 3R) (3) (2R, 3S) (4) (2S, 3R)

Q40.Assertion: Among the carbon allotropes, diamond is an insulator, whereas, graphite is a good conductor of electricity. Reason: Hybridization of carbon in diamond and graphite are sp3 and sp2 respectively. (1) Both assertion and reason are correct, but the (2) Both assertion and reason are correct, but the reason is not the correct explanation for the reason is the correct explanation for the assertion. assertion. (3) Both assertion and reason are incorrect. (4) Assertion is incorrect statement, but the reason is correct. JEE Main 2016 (10 Apr Online) JEE Main Previous Year Paper

Q40.The correct order of the solubility of alkaline-earth metal sulphates in water is: (1) Mg > Ca > Sr > Ba (2) Mg > Sr > Ca > Ba (3) Mg < Ca < Sr < Ba (4) Mg < Sr < Ca < Ba

Q41.Match the items in Column I with its main use listed in Column II: Column I Column II A Silica gel i. Transistor B Silicon ii. Ion-exchanger C Silicone iii. Drying agent D Silicate iv. Sealant (1) A − iii, B − i, C − iv, D −ii (2) A − iv, B − i, C − ii, D − iii (3) A − ii, B − i, C − iv, D − iii (4) A − ii, B − iv, C − i, D − iii

Q41.Sodium extract is heated with concentrated HNO3 before testing for halogens because : (1) Ag2S and AgCN are soluble in acidic medium. (2) Silver halides are totally insoluble in nitric acid. (3) S2− and CN− , if present, are decomposed by (4) Ag reacts faster with halides in acidic medium conc. HNO3 and hence do not interfere in the test.