﻿ Dihedral angle between two methyl groups of n-butane in the gauch

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# 21.Dihedral angle between two methyl groups of n-butane in the gauche and anti forms are60°, 0° 0°, 60° 60$°$, 180° 180°, 60°

C.

60$°$, 180°

The angle between C-C and C-H bonds on adjacent carbon atoms in any conformation is called dihedral angle. Hence, the dihedral angle in case of gauche is 60°and in anti form is 180°. 22.

The vapour pressure of 100g water reduces from 3000 Nm-2 to 2985 Nm-2 when 5g of substance 'X' is dissolved in it. Substance 'X' is

• methanol

• glucose

• carbon dioxide

• cannot predict

23.

The complex ion which has no d-electrons in the central metal atom is

• [MnO4]-

• [Co(NH3)6]3+

• [Fe(CN)6]3-

• [Cr(H2O)6]3+

24.

White P reacts with caustic soda, the products are PH3 and NaH2PO2. This reaction is an example of

• hydrolysis

• reduction

• disproportionation

• neutralisation

25.

The solubility of saturated solution of Ag2CrO4 is s mol L-1. What is its solubility product?

• 4s3

• s3

• 2s3

• 16s2

26.

For a reaction, A+ B $\to$ Product, the rate is given by,

r = k[A]1/2[B]2

What is the order of the reaction?

• 0.5

• 2

• 2.5

• 1

27.

How long it will take to deposit 1.0 g of chromium when a current of 1.25 A flows through a solution of chromium (III) sulphate ? (Molar mass of Cr = 52)

• 1.24 min

• 1.24 h

• 1.24 s

• None of these

28.

If a be the edge length of the unit cell and r be the radius of an atom then for fee arrangement, the correct relation is

• 4a = $\sqrt{3}$r

• 4r = $\sqrt{3}$a

• 4r = $\sqrt{2}$a

• 4r = $\frac{\mathrm{a}}{\sqrt{2}}$

29.

The number of phase in a colloidal system is

• 1

• 2

• 3

• 4

30.

A solid AB has the NaCl structure. If radius of cation A+ is 120 pm, the maximum possible value of the radius of the anion B- is

• 240 pm

• 60 pm

• 49.6 pm

• 290 pm