1
MCQ (Single Correct Answer)

AIPMT 2012 Prelims

In which of the following compounds, nitrogen exhibits highest oxidation state?
A
N2H4
B
NH3
C
N3H
D
NH2OH

Explanation

N2H4 : Oxidation state of N = – 2

NH3 : Oxidation state of N = – 3

N3H : Oxidation state of N = – 1/3

NH2OH : Oxidation state of N = – 1

$$ \therefore $$ Highest oxidation state = –1/3
2
MCQ (Single Correct Answer)

AIPMT 2012 Prelims

Which of the following statements is not valid for oxoacids of phosphorus?
A
Orthophosphoric acid is used in the manufacture of triple superphosphate.
B
Hypophosphorous acid is a diprotic acid.
C
All oxoacids contain tetrahedral four coordinated phosphorus.
D
All oxoacids contain atleast one P$$=$$O unit and one P$$-$$OH group.

Explanation

Hypophosphorus acid is a monoprotic acid.
3
MCQ (Single Correct Answer)

AIPMT 2011 Mains

Which of the following oxide is amphoteric?
A
SnO2
B
CaO
C
SiO2
D
CO2

Explanation

SnO2 reacts with acid as well as base. So SnO2 is an amphoteric.

SnO2 + 4HCl $$ \to $$ SnCl2 + 2H2O

SnO2 + 2NaOH $$ \to $$ Na2SnO3 + H2O

CaO is basic in nature while SiO2 and CO2 are acidic in nature.
4
MCQ (Single Correct Answer)

AIPMT 2011 Mains

Which of the following statements is incorrect?
A
Pure sodium metal dissolves in liquid ammonia to give blue solution.
B
NaOH reacts with glass to give sodium silicate.
C
Aluminium reacts with excess NaOH to give Al(OH)3.
D
NaHCO3 on heating gives Na2CO3.

Explanation

Al reacts with NaOH to give sodium metaaluminate.

2Al(s) + 2NaOH (aq) + 2H2O(l) $$ \to $$ 2NaAlO2 + 3H2

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