The p-Block Elements Test - 39

Ammonium iron(II) sulphate, or Mohr's salt, is the inorganic compound with the formula $$(NH_4)_2Fe(SO_4)_2·6H_2O$$. Containing two different cations, $$Fe^{2+}$$ and $$NH_4^{+}$$. It is classified as a double salt of ferrous sulphate and ammonium sulphate.

So Mohr's salt contains 6 water molecules.

Hence option $$B$$ is correct.

Boron does not usually react with acids and alkalis but it reacts with acids and alkalis in only highly divided state. When it reacts with $$HN{ O }_{ 3 }$$ it gives Boric acid. The reaction occurs at high temperature. 

As boron is predominantly a non-metal it hardly loses the electrons and forms ionic bonds. It always forms covalent  bonds due to following reasons
1) Small size
2) High nuclear charge
3) High ionisation energy
Hence option $$A,C$$ is correct.

In thermite welding, aluminium dust is oxidised by the oxide of another metal, most commonly iron oxide, because aluminium is highly reactive. Iron(III) oxide is commonly used:

$$Fe_2O_3+2Al\rightarrow Al_2O_3+2Fe$$.

So oxidation of $$Al$$ takes place in thermite welding

Hence option $$D$$ is correct.

Boron shows single oxidation state due to absence of inert pair effect.It means that the $$1S^{2}$$ electrons in boron participate in chemical bonding(Non participation inner ns electrons in bonding is inert pair effect).
Hence option A is correct.

In 3rd A group Tl shows +1 oxidation state while other member shows +3 oxidation state due to inert pair effect. The inert pair effect is the tendency of the electrons in the outermost atomic S orbital to remain unionized or unshared in compounds of post-transition metals.

So in $$Tl$$ only outer electron 1.e $$np^{1}$$ partcipate in chemical bonding where as the $$ns^{2}$$ do not particicpate in chemical bonding in a achemical reaction but other elements in that group do not show inert pair effect.

Hence option B is correct.

The Bayer process is the principal industrial method  of refining bauxite to produce alumina (aluminium oxide $$Al_2O_3$$). Bauxite, the most important ore of aluminium, contains only 30–54% aluminium oxide, (alumina).
Hence option C is correct.

Catenation is the linkage of atoms of the same element into longer chains. Catenation occurs most readily in carbon, which forms covalent bonds with other carbon atoms to form longer chains and structures.

As we move down the group as the size of the atom increases the catenating (linkage of atoms of the same element into longer chains.) ability of an element decreases. So in the given 4th group elements $$Sn$$ is having least size. So it has the least tendency of catenation.
Hence option $$D$$ is correct.