21816.If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water (ΔTf), when 0.01 mol of sodium sulphate is dissolved in 1 kg of water is (Kf = 1.86 K kg mol–1)
0.0744 K
0.0186 K
0.0372 K
0.0558 K
21817.6.02 × 1020 molecules of urea are present in 100 mL of its solution. The concentration of urea solution is (Avogadro constant, NA = 6.02 × 1023 mol–1)
0.001 M
0.01 M
0.02 M
0.1 M
21818.1.00 g of non–electrolyte solute (molar mass 250 g mol–1) was dissolved in 51.2 g of benzene. If the freezing point depression constant, Kf of benzene is 5.12 K kg mol–1, the freezing point of benzene will be lowered by
0.3 K
0.5 K
0.2 K
0.4 K
21819.An aqueous solution is 1.00 molal in KI. Which change will cause the vapour pressure of the solution to increase?
addition of 1.00 molal KI
addition of water
addition of NaCl
addition of Na2SO4
21820.The molarity of a NaOH solution by dissolving 4 g of it in 250 ml water is
0.4 M
0.8 M
0.2 M
0.1 M
21821.What is the osmotic pressure of a 0.0020 mol dm–3 sucrose (C12H22O11) solution at 20°C? (Molar gas constant, R = 8.314 JK–1 mol–1, 1 dm3 = 0.001 m3?
4870 Pa
4.87 Pa
0.00487 Pa
0.33 Pa
21822.The Henry's law constant for the solubility of N2 gas in water at 298 K is 1.0 × 105 atm. The mole fraction of N2 in air is 0.8. The number of moles of N2 from air dissolved in 10 moles of water at 298 K and 5 atm pressure is
4.0 × 10–4
4.0 × 10–5
5.0 × 10–4
4.0 × 10–6
21823.0.5 molal aqueous solution of a weak acid (HX) is 20% ionized. If Kf for water is 1.86 K kg mol–1, the lowering in freezing point of the solution is
–0.56 K
–1.12 K
0.56 K
1.12 K
21824.pA and pB are the vapour pressure of pure liquid components, A and B, respectively of an ideal binary solution. If xA represents the mole fraction of component A, the total pressure of the solution will be
pB + xA (pB – pA)
pB + xA (pA – pB)
pA + xA (pB – pA)
pA + xA (pA – pB)
21825.Benzene and toluene form nearly ideal solutions. At 20°C, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The partial vapour pressure of benzene at 20°C for a solution containing 78 g of benzene and 46 g of toluene in torr is
25
50
53.5
37.5
21826.6.02 × 1020 molecules of urea are present in 100 mL of its solution. The concentration ofsolution is
0.02 M
0.01 M
0.001 M
0.1 M
21827.A solution of sucrose (molar mass = 342 g mol–1) has been prepared by dissolving 68.5 g of sucrose in 100 g of water. The freezing point of the solution obtained will be (Kf for water = 1.86 K kg mol–1)
+ 0.372°C
– 0.570°C
– 0.372°C
– 0.520°C
21828.A 5% solution of cane sugar (molar mass 342 g mol–1) is isotonic with 1% of a solution of an unknown solute. The molar mass of unknown solute in g/mol is
34.2
136.2
171.2
68.4
21829.A 0.0020 m aqueous solution of an ionic compound Co(NH3)5(NO2)Cl freezes at –0.00732°C. Number of moles of ions which 1 mol of ionic compound produces on being dissolved inwater will be (kf = 1.86°C/m)
3
4
1
2
21830.How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0 M HNO3? The concentrated acid is 70% HNO3.
45.0 g conc. HNO3
90.0 g conc. HNO3
70.0 g conc. HNO3
54.0 g conc. HNO3
21831.After removing the hard shell of an egg by dissolving in dil. HCl, a semipermeable membrane is visible. If such an egg is kept in a saturated solution of common salt the size of the egg will
shrink
grow
remain the same
first shrink and then grow larger
21832.18 g of glucose (C6H12O6) is added to 178.2 g of water. The vapour pressure of water for this aqueous solution at 100°C is
7.60 torr
76.00 torr
752.40 torr
759.00 torr
21833.A 5.25% solution of a substance is isotonic with a 1.5% solution of urea (molar mass = 60 g mol–1) in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 g cm–3, molar mass of the substance will be
90.0 g mol–1
115.0 g mol–1
105.0 g mol–1
210.0 g mol–1
21834.At 80°C the vapour pressure of pure liquid ‘A’ is 520 mm Hg and that of pure liquid ‘B’ is 1000 mm Hg. If a mixture of solution of 'A’ and ‘B’ boils at 80°C and 1 atm pressure, the amount of ‘A’ in the mixture is (1 atm = 760 mm Hg)
50 mol percent
52 mol percent
34 mol percent
48 mol percent
21835.Solution A contains 7g/L of MgCl2 and solution B contains 7g/L of NaCl. At room temperature, the osmotic pressure of:
solution B is greater than A
both have same osmotic pressure
solution A is greater than B
can't determine