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.

(a) [Cu(CN)₄]^3-,(CN)₂

(b) CuCn,(CN)₂

(c) [Cu(CN)₄]^2-,(CN)₂

(d) 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:

(a) 6,8

(b) 6,5

(c) 8,6

(d) 7,7

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

(a) Fe₂O₃ +H₂

(b) Fe₃O₄ +H₂

(c) FeO +H₂

(d) 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

Consider the following transformation:

2CuX₂$\stackrel{\mathrm{room} \mathrm{temperature}}{\to }$2CuX+X₂$\uparrow$

Then X^- can be :

(a) F^-,Br^-

(b) Cl^-,Br^-

(c) CN^-

(d) Cl^-,F^-

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