Lanthanoid contraction is caused due to :
1. the appreciable shielding on outer electrons by 4f electrons from the nuclear charge
2. the appreciable shielding on outer electrons by 5d electrons from the nuclear charge
3. the same effective nuclear charge from Ce to Lu
4. the imperfect shielding on outer electrons by 4f electrons from the nuclear charge
Elements that generally exhibit multiple oxidation states and whose ions in an aqueous medium are usually colored are:
1. Metalloids
2. Transition elements
3. Non-metals
4. Noble gases
CuSO4 (aq.)MN+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
CrO42- (yellow) changes to Cr2O72- (orange) in pH = x and vice versa in pH = y.
The value of x and y will be:
1. 6, and 8
2. 6, and 5
3. 8, and 6
4. 7, and 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?
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
The colour of KMnO4 is due to :
1. d-d transition
2. Charge transfer spectra
3. Polarisation of ion
4. p-d transition