The low melting point of manganese in the 1st transition series is due to:

1. strong metallic bond due to d¹⁰ configuration

2. weak metallic bond due to d⁵ configuration

3. weak metallic bond due to d⁷ configuration

4. none of the above

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

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?

1. NaBr

2. NaCl

3. NaNO₃

4. NaI

Fe is made passive by :

1. dil . H₂SO₄

2. dil. HCl

3. Conc. HNO₃

4. Conc. H₂SO₄

The iron salt used in blue prints is:

1. FeC₂O₄

2. Fe₂(C₂O₄)₃

3. K₄Fe(CN)₆

4. FeSO₄

Which element among the following has the highest melting point?

1. Cr

2. Fe

3. Cu

4. Mo

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

Basic oxide amongst the following is:

1. CrO

2. Cr₂O₃

3. CrO₃

4. Cr₂O₄