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# NEET Chemistry Solved Question Paper 2010

#### Multiple Choice Questions

21.

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

B.

glucose

180 is the molecular weight of glucose (C6H12O6), thus the substance X is glucose.

22.

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

• hydrolysis

• reduction

• disproportionation

• neutralisation

C.

disproportionation

The above reaction is an example of disproportionation reaction, i.e. the reaction in which oxidation and reduction take place simultaneously.

23.

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 = $\frac{\mathrm{a}}{\sqrt{2}}$

C.

4r = $\sqrt{2}$a

Given, the edge length of the unit cell = a and, radius of the sphere = r

Consider $∆$ABC,

AC2 = AB+ AC2

= a2 + a2

= 2a2

Therefore, AC = $\sqrt{2}$a

But, in figure, AC = 4r

Therefore, 4r = $\sqrt{2}$a

24.

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

B.

1.24 h

Cr3+ + 3e- $\to$ Cr(s)

3 mol or 3 x 96500 C of electricity are needed to deposit 1 mol or 52 g of Cr

52 gm of Cr will require current = 3 x 96500C

1 gm of Cr will require current =  = 5567.3C

Now, number of coulombs = current (ampere) x t (seconds)

25.

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+

A.

[MnO4]-

In [MnO4]-, the oxidation state of Mn is + 7

Mn(25) = [Ar] 3d54s2

Mn7+ = [Ar]

Thus, in [MnO4]- no d-electron is present.

26.

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

D.

290 pm

For NaCl crystal,

Radius of cation/ radius of anion = 0.414

$\frac{{\mathrm{r}}_{{\mathrm{A}}^{+}}}{{\mathrm{r}}_{{\mathrm{B}}^{-}}}$ = 0.414

27.

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

C.

2.5

Order of a reaction is the sum of the power to which the concentration terms are raised in the rate law equation to express the observed rate of the reaction

Hence, order =

# 28.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°.

29.

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

• 4s3

• s3

• 2s3

• 16s2

A.

4s3

Ag2CrO4 $\to$ 2Ag+ + Cr${\mathrm{O}}_{4}^{2-}$

s mol/L      2s mol/L  s mol/L

Hence, the solubility product is

Ksp of Ag2CrO4 = [Ag+]2[Cr${\mathrm{O}}_{4}^{2-}$]

= (2s)2(s)

= 4s3

Therefore, 4s3 is the solubility product.

30.

The number of phase in a colloidal system is

• 1

• 2

• 3

• 4

B.

2

Colloidal solution is of heterogeneous nature. It consists oftwo phases ie, a dispersed phase and a dispersion medium.