NEW
New Website Launch
Experience the best way to solve previous year questions with mock tests (very detailed analysis), bookmark your favourite questions, practice etc...
1

AIPMT 2008

MCQ (Single Correct Answer)
Number of moles of MnO$$_4^{ - }$$ required to oxidize one mole of ferrous oxalate completely in acidic medium will be
A
7.5 moles
B
0.2 moles
C
0.6 moles
D
0.4 moles

Explanation

The balanced ionic equation for oxidation of ferrous oxalate by MnO4 in acidic medium is as follows :

3MnO4- + 5FeC2O4 + 24H+ $$ \to $$

3Mn2+ + 10CO2 + 12H2O + 5Fe3+

Thus, 5 moles of FeC2O4 require 3 moles of MnO4-.

So, 1 mole of FeC2O4 requires

= $${3 \over 5}$$ = 0.6 moles of MnO4-
2

AIPMT 2004

MCQ (Single Correct Answer)
Which is the best description of the behaviour of bromine in the reaction given below?
H2O + Br2 $$ \to $$ HOBr + HBr
A
Proton acceptor only
B
Both oxidised and reduced
C
Oxidised only
D
Reduced only

Explanation

H2O + $${\mathop {Br}\limits^0}$$2 $$ \to $$ HO$$\mathop {Br}\limits^{ + 1} $$ + H$$\mathop {Br}\limits^{ - 1} $$

In the above reaction the oxidation number of Br2 increases from zero (in Br2 ) to +1 (in HOBr) and decreases from zero (in Br2 ) to –1 (in HBr). Thus Br2 is oxidised as well as reduced and hence it is a redox reaction.
3

AIPMT 2003

MCQ (Single Correct Answer)
The oxidation states of sulphur in the anions

SO3$${_3^{2 - }}$$, S2O$${_4^{2 - }}$$ and S2O$${_6^{2 - }}$$ follow the order
A
S2O$${_4^{2 - }}$$ < SO$${_3^{2 - }}$$ < S2O$${_6^{2 - }}$$
B
SO$${_3^{2 - }}$$ < S2O$${_4^{2 - }}$$ < S2O$${_6^{2 - }}$$
C
S2O$${_4^{2 - }}$$ < S2O$${_6^{2 - }}$$ < SO$${_3^{2 - }}$$
D
S2O$${_6^{2 - }}$$ < S2O$${_4^{2 - }}$$ < SO$${_3^{2 - }}$$

Explanation

SO32– : oxidation state of ‘S’ is +4

S2O42– : oxidation state of ‘S’ is +3.

S2O62– : oxidation state of ‘S’ is +5.

So, the order is S2O$${_4^{2 - }}$$ < SO$${_3^{2 - }}$$ < S2O$${_6^{2 - }}$$.

Joint Entrance Examination

JEE Main JEE Advanced WB JEE

Graduate Aptitude Test in Engineering

GATE CSE GATE ECE GATE EE GATE ME GATE CE GATE PI GATE IN

Medical

NEET

CBSE

Class 12