﻿ The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (Atomic mass Al= 27) from Chemistry NEET Year 2007 Free Solved Previous Year Papers

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# 1.The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (Atomic mass Al= 27)180 kg 270 kg 540 kg 90 kg

D.

90 kg

In Hall and Heroult process

2Al2O3 $\to$ 4Al + 3O2

4C + 3O2 $\to$ 2CO2 + 2CO $↑$

2Al2O3 + 4C $\to$4Al + 2CO2 + 2CO

Only for removal of CO2, following equation is possible

2Al2O3 + 3C $\to$4Al + 3CO2

Molecular weight of Carbon = 12

Molecular weight of Aluminium = 27

$\therefore$ For Carbon/ C = 3 x 12 = 36

For Aluminium/ Al = 4 x 27 = 108

$\because$ For 108 gm of Al, 36 gm of C is required in above reaction

$\therefore$ For 270 gm of Al require amount of C =

2.

The number of moles of KMnO4 reduced by one mole of KI in alkaline medium is

• one-fifth

• five

• one

• two

3.

Which of the following molecules has trigonal planar geometry?

• IF3

• PCl3

• NH3

• BF3

4.

A reaction occurs spontaneously if

• T$∆$S < $∆$H and both $∆$H and $∆$S are +ve

• T$∆$S > $∆$H and both $∆$H and $∆$S are +ve

• T$∆$S = $∆$H and both $∆$H and $∆$S are +ve

• T$∆$S > $∆$H and $∆$H is +ve and $∆$S is - ve

5.

The correct sequence of increasing covalent character is represented by

• LiCl < NaCl < BeCl2

• BeCl2 < NaCl < LiCl

• NaCl < LiCl < BeCl2

• BeCl2 < LiCl < NaCl

6.

Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?

• Exothermic and decreasing disorder

• Endothermic and increasing disorder

• Exothermic and increasing disorder

• Endothermic and decreasing disorder

7.

Which of the following is the electron deficient molecule?

• B2H6

• C2H6

• PH3

• SiH4

8.

A nuclide of an alkaline earth metal undergoes radioactive decay by emission of three $\mathrm{\alpha }$-particles in succession. The group of the periodic table to which the resulting daughter element would belong to

• Group 14

• Group 16

• Group 4

• Group 6

9.

The absolute enthalpy of neutralisation of the reaction

MgO(s) + 2HCl(aq) $\to$ MgCl2(aq) + H2O(l)

will be

• less than - 57.33 kJ mol-1

• - 57.33 kJ mol-1

• greater than-- 57.33 kJ mol-1

• 57.33 kJ mol-1

10.

Equilibrium constants K1 and K2 for the following equilibria
NO (g) +  $\stackrel{{\mathrm{K}}_{1}}{⇌}$ NO2(g) and

2NO2(g) $\stackrel{{\mathrm{K}}_{2}}{⇌}$ 2NO (g) + O2(g)

are related as