1. Identify the statement that is not correct as far as structure of diborane is concerned
a) There are two bridging hydrogen atoms and four terminal hydrogen atoms in diborane
b) Each boron atom forms four bonds in diborane
c) The hydrogen atoms are not in the same plane in diborane
d) All, B – H bonds in diborane are similar
Explanation: All, B – H bonds in diborane are similar
2. \[BCl_{3}\] does not exist as dimer but \[BH_{3}\] exists as dimer \[\left(B_{2}H_{6}\right)\] because
a) chlorine is more electronegative than hydrogen
b) there is \[p\pi-p\pi\] back bonding in \[BCl_{3}\] but \[BH_{3}\] does not contain such multiple bonding
c) large sized chlorine atoms do not fit in between the small boron atoms where as small sized hydrogen atoms get fitted in between boron atoms
d) None of these
Explanation: \[BCl_{3}\] does not exist as dimer but \[BH_{3}\] exists as dimer \[\left(B_{2}H_{6}\right)\] because large sized chlorine atoms do not fit in between the small boron atoms where as small sized hydrogen atoms get fitted in between boron atoms
3. Diborane upon hydrolysis gives
a) boric anhydride
b) metaboric acid
c) orthoboric acid
d) boron oxide
Explanation: Diborane upon hydrolysis gives orthoboric acid
4. In reaction
\[BF_{3} + 3LiBH_{4} \rightarrow 3LiF + X ;\]
X is
a) \[B_{4}H_{10}\]
b) \[B_{2}H_{6}\]
c) \[BH_{3}\]
d) \[B_{3}H_{8}\]
Explanation: \[B_{2}H_{6}\]
5. Which of the following mineral does not contain Al ?
a) Cryolite
b) Mica
c) Feldspar
d) Fluorspar
Explanation:
6. In the thermite welding process we use
a) Al powder
b) Fe powder
c) Ca powder
d) (Al + Fe) mixture
Explanation: Al powder
7.In aluminates, the coordination number of Al is
a) 4
b) 6
c) 3
d) 1
Explanation: In aqueous solution the probable aluminate species is [Al(H2O)2(OH)4] hence Al containing co-ordination number 6
8. Aluminium is
a) a reducing agent
b) an oxidising agent
c) amphoteric
d) highly electronegative element
Explanation: Because it can lose electrons
9. Al is more reactive than Fe but Al is less easilly corroded
than Fe because
a) it is a noble metal
b) oxygen forms a protective oxide layer
c) iron undergoes reaction easily with water
d) Fe form mono and divalent ions
Explanation: The protective oxide layer prevents Al from further corrosion
10. Corundum is
a) \[Al_{2}\left(SO_{4}\right)_{3}\]
b) \[Al_{2}O_{3}.H_{2}O\]
c) \[Al_{2}O_{3}.2H_{2}O\]
d) \[Al_{2}O_{3}\]
Explanation: \[Al_{2}O_{3}\]