Zr (Z=40) and Hf (Z=72) have similar atomic and ionic radii because of :
a.
lanthanoid contraction
Correct Answer
b.
having similar chemical properties
c.
belonging to same group
d.
diagonal relationship
Step-by-Step AI Explanation
Verified Method
The similarity in radii of Zr and Hf is a direct consequence of lanthanoid contraction, where the filling of 4f orbitals leads to poor shielding, increasing effective nuclear charge.
Q52mcq
The right option for the statement “Tyndall effect is exhibited by”, is :
a.
Starch solution
Correct Answer
b.
Urea solution
c.
NaCl solution
d.
Glucose solution
Step-by-Step AI Explanation
Verified Method
Tyndall effect is exhibited by colloidal solutions. Among the options, Starch solution is a colloid, while the others are true solutions.
Q53mcq
Match List - I with List - II. List - I (a)PCl5 (b)SF6 (c)BrF5 (d)BF3 List - II (i)Square pyramidal (ii)Trigonal planar (iii)Octahedral (iv)Trigonal bipyramidal
PCl5 is trigonal bipyramidal (iv), SF6 is octahedral (iii), BrF5 is square pyramidal (i), BF3 is trigonal planar (ii).
Q54mcq
The pKb of dimethylamine and pKa of acetic acid are 3.27 and 4.77 respectively at T (K). The correct option for the pH of dimethylammonium acetate solution is :
a.
7.75
Correct Answer
b.
6.25
c.
8.50
d.
5.50
Step-by-Step AI Explanation
Verified Method
For a salt of a weak acid and weak base, pH = 7 + 0.5(pKa - pKb). pH = 7 + 0.5(4.77 - 3.27) = 7 + 0.5(1.5) = 7 + 0.75 = 7.75.
Q54mcq
The pKb of dimethylamine and pKa of acetic acid are 3.27 and 4.77 respectively at T (K). The correct option for the pH of dimethylammonium acetate solution is :
An organic compound contains 78% (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is : [Atomic wt. of C is 12, H is 1]
a.
CH3
b.
CH4
c.
CH
d.
CH2
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Statement I: Acid strength increases in the order given as HF << HCl << HBr << HI. Statement II: As the size of the elements F, Cl, Br, I increases down the group, the bond strength of HF, HCl, HBr and HI decreases and so the acid strength increases. In the light of the above statements, choose the correct answer from the options given below.
a.
Statement I is correct but Statement II is false.
b.
Statement I is incorrect but Statement II is true.
c.
Both Statement I and Statement II are true.
d.
Both Statement I and Statement II are false.
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The molar conductance of NaCl, HCl and CH3COONa at infinite dilution are 126.45, 426.16 and 91.0 S cm^2 mol^-1 respectively. The molar conductance of CH3COOH at infinite dilution is.
a.
698.28 S cm^2 mol^-1
b.
540.48 S cm^2 mol^-1
c.
201.28 S cm^2 mol^-1
d.
390.71 S cm^2 mol^-1
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The following solutions were prepared by dissolving 10 g of glucose, 10 g of urea, and 10 g of sucrose in 250 ml of water. The right option for the decreasing order of osmotic pressure of these solutions is:
a.
P2 > P3 > P1
b.
P3 > P1 > P2
c.
P2 > P1 > P3
d.
P1 > P2 > P3
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The following solutions were prepared by dissolving 10 g of glucose (C6H12O6) in 250 ml of water (P1), 10 g of urea (CH4N2O) in 250 ml of water (P2) and 10 g of sucrose (C12H22O11) in 250 ml of water (P3). The right option for the decreasing order of osmotic pressure of these solutions is :
a.
P2 > P3 > P1
b.
P3 > P1 > P2
c.
P2 > P1 > P3
d.
P1 > P2 > P3
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The correct option for the value of vapour pressure of a solution at 45°C with benzene to octane in molar ratio 3 : 2 is : [At 45°C vapour pressure of benzene is 280 mm Hg and that of octane is 420 mm Hg. Assume Ideal gas]
a.
336 mm of Hg
b.
350 mm of Hg
c.
160 mm of Hg
d.
168 mm of Hg
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Choose the correct option for the total pressure (in atm.) in a mixture of 4 g O2 and 2 g H2 confined in a total volume of one litre at 0°C is : [Given R=0.082 L atm mol−1 K−1, T=273 K]
a.
25.18
b.
26.02
c.
2.518
d.
2.602
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Choose the correct option for the total pressure (in atm.) in a mixture of 4 g O2 and 2 g H2 confined in a total volume of one litre at 0°C. [Given R=0.082 L atm mol−1 K−1, T=273 K]
a.
25.18
b.
26.02
c.
2.518
d.
2.602
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Match List - I with List - II. List - I: (a) [Fe(CN)6]3−, (b) [Fe(H2O)6]3+, (c) [Fe(CN)6]4−, (d) [Fe(H2O)6]2+. List - II: (i) 5.92 BM, (ii) 0 BM, (iii) 4.90 BM, (iv) 1.73 BM.
a.
(a)-(i), (b)-(iii), (c)-(iv), (d)-(ii)
b.
(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
c.
(a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)
d.
(a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
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The molar conductivity of 0.007 M acetic acid is 20 S cm2 mol−1. What is the dissociation constant of acetic acid? Given: Λ°H+ = 350 S cm2 mol−1, Λ°CH3COO− = 50 S cm2 mol−1.
a.
1.75×10−5 mol L−1
b.
2.50×10−5 mol L−1
c.
1.75×10−4 mol L−1
d.
2.50×10−4 mol L−1
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