Platinum, palladium and iridium are called noble metals because

• Alfred Nobel discovered them

• they are shining lustrous and pleasing to look at

• they are found in native state

• they are inert towards many common reagents

NO₂ is not obtained on heating

• AgNO₃

• KNO₃

• Cu(NO₃)₂

• Pb(NO3)2

A solution of KMnO₄ is reduced to a various products depending upon its pH. At pH<7, it is reduced to a colourless solution (A), at pH =7 it forms a brown precipitate (B) and at pH> 7, it gives a green solution (C).(A), (B) and (C) are

• A	B	C
  Mn2+	MnO2	${\mathrm{MnO}}_4^{2-}$

• A	B	C
  MnO2	Mn2+	${\mathrm{MnO}}_4^{2-}$

• A	B	C
  ${\mathrm{MnO}}_4^{2-}$	Mn2+	MnO2

• A	B	C
  Mn2+	${\mathrm{MnO}}_4^{2-}$	MnO2

Which of the following reactions depict the oxidising behavior of H₂SO₄?

• $2{\mathrm{PCl}}_5 + {\mathrm{H}}_2{\mathrm{SO}}_4 \to 2{\mathrm{POCl}}_3 + 2\mathrm{HCl} +{\mathrm{SO}}_2{\mathrm{Cl}}_2$

• $2\mathrm{NaOH} + {\mathrm{H}}_2{\mathrm{SO}}_4 \to {\mathrm{Na}}_2{\mathrm{SO}}_4 + 2{\mathrm{H}}_2\mathrm{O}$

• $\mathrm{NaCl} + {\mathrm{H}}_2{\mathrm{SO}}_4 \to {\mathrm{NaHSO}}_4 + \mathrm{HCl}$

• $2\mathrm{HI} +{\mathrm{H}}_2{\mathrm{SO}}_4 \to {\mathrm{I}}_2 + {\mathrm{SO}}_{2 }+ 2{\mathrm{H}}_2\mathrm{O}$

245.

Which two sets of reactants best represents the amphoteric character of Zn(OH)₂?

Set I - Zn(OH)₂(s) and OH^- (aq)

Set II - Zn(OH)₂(s) and H₂O (I)

Set III - Zn(OH)₂ (s) and H⁺ (aq)

Set IV - Zn(OH)₂(s) and NH₃ (aq)

• III and II

• I and III

• IV and I

• II and IV

An organic compound having carbon, hydrogen and sulphur contains 4% of sulphur. The minimum molecular weight of
the compound is

• 200

• 400

• 600

• 800

Which has the smallest size?

• Na⁺

• Mg²⁺

• Al³⁺

• P⁵⁺

The bond angles of ${\mathrm{NH}}_3 > {\mathrm{NH}}_4^{+} \mathrm{and} {\mathrm{NH}}_2^{-}$ are in the order

• ${\mathrm{NH}}_2^{-} > {\mathrm{NH}}_3 > {\mathrm{NH}}_4^{+}$

• ${\mathrm{NH}}_4^{+} >{\mathrm{NH}}_3 > {\mathrm{NH}}_2^{-}$

• ${\mathrm{NH}}_3>{\mathrm{NH}}_2^{-} >{\mathrm{NH}}_4^{+}$

• $\mathrm{NH} > {\mathrm{NH}}_4^{+} > {\mathrm{NH}}_2^{-}$

Amongest NO${}_3^{-}$, AsO${}_3^{3-}$-, CO${}_3^{2-}$, ClO${}_3^{-}$, SO${}_3^{2-}$ and BO${}_3^{3-}$, the non-planar species are

• CO${}_{\mathrm{}}^{$ {}_3^{2-}$}$

• AsO${}_3^{3-}$, ClO${}_3^{-}$ and SO${}_3^{2-}$

• NO${}_3^{-}$, CO${}_3^{2-}$ and BO${}_3^{3-}$

• SO${}_3^{2-}$, NO${}_3^{-}$ and BO${}_3^{3-}$

Iodine is formed when potassium iodide reacts with a solution of

• ZnSO₄

• CuSO₄

• (NH₄)₂SO₄

• Na₂SO₄