Practice Questions

Q48.How much amount of NaCl should be added to 600 g of water (ρ = 1.00g/mL) to decrease the freezing point of water to −0.2 oC? ________. (The freezing point depression constant for water = 2 K kgmol−1 ) Q49. 108 g of silver (molar mass 108 gmol−1 ) is deposited at cathode from AgNO3(aq) solution by a certain quantity of electricity. The volume (in L ) of oxygen gas produced at 273 K and 1 bar pressure from water by the same quantity of electricity is ________

Q48.A sample of milk splits after 60min . at 300K and after 40min . at 400K when the population of Iactobacillus acidophilus in it doubles. The activation energy (in kJ / mol ) for this process is closest to ______________. (Given, R = 8.3Jmol−1K−1, ln( 23 ) = 0.4, e−3 = 4.0 )

Q48.The number of chiral carbons present in the molecule given below is.............. JEE Main 2020 (02 Sep Shift 1) JEE Main Previous Year Paper

Q48.The heat of combustion of ethanol into carbon dioxides and water is −327 Kcal at constant pressure. The heat evolved (in cal) at constant volume at 27° C (if all gases behave ideally) is (R = 2 calmol−1 K−1) ________

Q48.The total number of monohalogenated organic products in the following (including stereoisomers) reaction is (i) H2/ Ni /Δ −A → (Simplest optically active alkene) (ii) X2/Δ

Q48.An acidic solution of dichromate is electrolyzed for 8 minutes using 2 A current. As per the following equation Cr2 O27 + 14H+ + 6e−→2 Cr3+ + 7H2O The amount of Cr3+ . obtained was 0. 104g. The efficiency of the process (in %) is (Take : F = 960000C, At. mass of chromium = 52)

Q48.The osmotic pressure of a solution of NaCl is 0. 10 atm and that of a glucose solution is 0. 20 atm. The osmotic pressure of a solution formed by mixing 1 L of the sodium chloride solution with 2 L of the glucose solution is x × 10−3 atm. x is ________ (nearest integer)

Q48.An oxidation-reduction reaction in which 3 electrons are transferred has a ΔG0 of 17. 37 kJ mol−1 at 25°C. The value of Eocell (in V) is _______ ×10−2 . (1F = 96500 C mol−1)

Q48.The volume, in mL, of 0. 02 MK2 Cr2 O7, solution required to react with 0. 288g of ferrous oxalate in acidic medium is … … … … (Molar mass of Fe = 56 gmol−1 )

Q48.The elevation of boiling point of 0. 10m aqueous CrCl3. xNH3 solution is two times that of 0. 05 m aqueous CaCl2 solution. The value of x is … … … … . . [Assume 100% ionisation of the complex and CaCl2, coordination number of Cr as 6, and that all NH3 molecules are present inside the coordination sphere]

Q49.The sum of the total number of bonds between chromium and oxygen atoms in chromate and dichromate ions is ______________. JEE Main 2020 (09 Jan Shift 2) JEE Main Previous Year Paper

Q49.The flocculation value of HCl for arsenic sulphide sol is 30 mmolL−1 . If H2SO4 is used for the flocculation of arsenic sulphide, the amount, in grams, of H2SO4 in 250ml required for the above purpose is ________ (molecular mass of H2SO4 = 98 g/mol

Q49.What would be the electrode potential for the given half-cell reaction at pH = 5? _________. ⊕ 2H2O →O2 + 4 H + 4e−; E0red = 1.23V (R = 8.314Jmol−1K−1; Temp = 298K; oxygen under s tan dard . atm. pressureof1bar)

Q49.The volume (in mL ) of 0. 1 N NaOH required to neutralise 10 mL of 0. 1 N phosphinic acid is ____________.

Q49.Chlorine reacts with hot and concentrated NaOH and produces compounds (X) and (Y). Compound (X) gives white precipitate with silver nitrate solution. The average bond order between Cl and O atoms in (Y) is _______________.

Q49.An element with molar mass 2 .7 ×10−2 kg mol−1 forms a cubic unit cell with edge length 405 pm. If its density is 2. 7 × 103 kg m−3 , the radius of the element is approximately … … … . ×10−12m (to the nearest integer)

Q49.Considering that Δ0 > P , the magnetic moment (in BM) of [Ru (H2O)6]2+ would be

Q49.For an electrochemical cell Sn(s) Sn2 + (aq, 1M) Pb2+(aq, 1M) Pb(s) the ratio [Sn2+] when this cell [Pb2+] attains equilibrium is _______ (Given: E0 = −0 .14 V, E0 = −0 .13 V, 2.303RTF = 0 .06 ) Sn2+ Sn Pb2+ Pb

Q49.The oxidation states of transition metal atoms in K2 Cr2 O7, KMnO4 and K2 FeO4, respectively, are x, y and z . The sum of x, y and z is______ JEE Main 2020 (02 Sep Shift 2) JEE Main Previous Year Paper

Q49.The number of molecules with energy greater than the threshold energy for a reaction increases five fold by a rise of temperature from 27oC to 42oC. Its energy of activation in J/ mol is _________ (Take ln 5 = 1. 6094; R = 8. 314 J mol−1 )

Q49.Potassium chlorate is prepared by the electrolysis of KCl in basic solution 6 OH−+ Cl−→ClO−3 + 3H2O + 6e− . If only 60% of the current is utilized in the reaction, the time (rounded to the nearest hour) required to produce 10g of KClO3 using a current of 2A is … … . . (Given : F = 96, 500Cmol; molar mass of KClO3 = 122 g mol−1 )

Q49.If 75% of a first order reaction was completed in 90 minutes, 60% of the same reaction would be completed in approximately (in minutes) _____ (Take: log 2 = 0.30 ; log 2.5 = 0.40)

Q49.For Freundlich adsorption isotherm, a plot of log (x/m) (y −axis) and log p(x −axis) gives a straight line, the intercept and slope fo rthe line is 0. 4771 and 2 , respectively. The mass of gas, adsorbed per gram of adsorbent if the initial pressure is 0. 04 atm is _____ ×10−4g .

Q49.The mass of gas adsorbed, x, per unit mass of adsorbate, m, was measured at various pressures, p. A graph between log mx and log p gives a straight line with slope equal to 2 and the intercept equal to 0. 4771 . The value of x at a pressure of 4 atm is : m (Given log 3 = 0. 4771 )

Q50.The number of chiral carbons present in sucrose is ……….