22517.Zn does notshow variable valency because of
complete d sub–shell
inert pair effect
4s2 sub–shell
None of these
22518.When copper pyrites is roasted in excess of air, a mixture of CuO + FeO is formed. FeO is present as impurities. This can be removed as slag during reduction of CuO. The flux added to form slag is:
SiO2, which is an acid flux
Lime stone, which is a basic flux
SiO2, which is basic flux
CaO; which is basic flux
22519.When AgNO3 solution is added in excess to 1 M solution of CoCl3, XNH3 one mole of AgCl is formed. What is the value of X?
1
2
3
4
22520.In chromite ore, the oxidation number of iron and chromium are respectively
+3, +2
+3, +6
+2, +6
+2, +3
22521.Lanthanide contraction is caused due to
the appreciable shielding on outer electrons by 4f electrons from the nuclear charge
the appreciable shielding on outer electrons by 5d electrons from the nuclear charge
the same effective nuclear charge from Ce to Lu
the imperfect shielding on outer electrons by 4f electrons from the nuclear charge
22522.‘Hydride Gap’ is referred to which region of the periodic table?
Groups 3, 4 and 5
Groups 5, 6 and 7
Groups 4, 5 and 6
Groups 7, 8 and 9
22523.The increasing order of the ionic radii of the given isoelectronic species is:
Cl–, Ca2+, K+, S2–
S2–, Cl–, Ca2+, K+
Ca2+, K+, Cl–, S2–
K+, S2–, Ca2+, Cl–