CuSO_4 (aq.)$\stackrel{{\mathrm{H}}_2\mathrm{S}\uparrow }{\to }$M$\downarrow$$\underset{\mathrm{of} \mathrm{KCN}}{\overset{\mathrm{Excess}}{\to }}$N+O

Then final products N and O are respectively.

1. [Cu(CN)₄]^3-,(CN)₂

2. CuCn,(CN)₂

3. [Cu(CN)₄]^2-,(CN)₂

4. Cu(CN)₂,K₂S

CrO₄^2- (yellow) changes to Cr₂O₇^2- (orange) in pH =x and vice versa in pH=y. Hence, x and y are:

1. 6,8

2. 6,5

3. 8,6

4. 7,7

When steam is passed over red hot iron , the substances formed are:

1. Fe₂O₃ +H₂

2. Fe₃O₄ +H₂

3. FeO +H₂

4. FeO+ H₂ +O₂

Which of the following solid salt on heating with K₂Cr₂O₇ and Conc. H₂SO₄ orange,red vapours are evolved which turn aquous NaOH solution yellow?

(a) NaBr

(b)NaCl

(c) NaNO₃

(d) NaI

Fe is made passive by :

(a) dil . H₂SO₄

(b) dil. HCl

(c) Conc. HNO₃

(d) Conc. H₂SO₄

The iron salt used in blue prints is:

(a) FeC₂O₄

(b) Fe₂(C₂O₄)₃

(c) K₄Fe(CN)₆

(d) FeSO₄

Which has highest melting point?

1. Cr

2. Fe

3. Cu

4. Mo

The colour of KMnO₄ is due to

1. d-d transition

2. Charge transfer spectra

3. Polarisation of ion

4. p-d transition

Which of the following element does not show the variable oxidation state?

1. Fe

2. Mn

3. Cu

4. Zn

With F highest stable oxidation state of Mn is

1. +6

2. +4

3. +7

4. +3