Which of the following is a Lewis acid?

1. ${\mathrm{AlCl}}_3$

2. ${\mathrm{MgCl}}_2$

3. ${\mathrm{CaCl}}_2$

4. ${\mathrm{BaCl}}_2$

Aluminium becomes passive in nitric acid because it:

1.  is a noble metal

2.  forms a thin film of oxide

3.  positive reduction potential

4.  none of the above

${\mathrm{Al}}_2{\mathrm{O}}_3$ reacts with 

1.  Only water

2.  Only acids

3.  Only alkalies

4.  Both acids and alkalies

The stability of +1 oxidation state among Al, Ga, In and Tl increases in the sequence?
1. Ga < ln < Al < Tl
2. Al < Ga < ln < Tl
3. Tl < ln < Ga < Al
4. ln < Tl < Ga < Al

Borax bead test is responded by:

1.  divalent metals

2.  heavy metals

3.  light metals

4.  metal which forms coloured metaborates

The correct statements among I to III regarding group 13 element oxides are:
(I) Boron trioxide or diboron trioxide is acidic.
(II) Oxides of aluminium and gallium are amphoteric.
(III) Oxides of indium and thallium are basic.
1. (I) and (II) only
2. (I) and (III) only
3. (II) and (III) only
4. (I), (II), and (III) only

The element which exists in a liquid state for a wide range of temperatures and can be used for measuring high temperature is:

The reason for the small radius of Ga compared to Al is-.

a.  Poor screening effect of d and f orbitals

b.  Increase in nuclear charge

c.  Presence of higher orbitals

d.  Higher atomic number

Choose the correct option
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)

The standard electrode potential values, E^o for Al³⁺/Al is –1.66 V and that of Tl³⁺/Tl is +1.26 V. The formation of M³⁺ ion in solution is favourable for-

1. Al has greater tendency than Tl.
2. Tl has greater tendency than Al
3. Both have equal tendency
4. Cannot predict.