Arachno-borane has the structural formula- B_nH_n+6.

BF₃ is a weaker Lewis acid than BCl₃ because of the greater pπ-pπ back bonding effect in BBr₃. BF₃ and BBr₃ both have sp² hybridisation with trigonal planar geometry.

Silver nitrate (AgNO₃) is known as Lunar caustic. The central metal in silver nitrate is nitrogen atom.

• 1 + x + 3(- 2) = 0 x - 5 = 0 x = + 5 Hence, the oxidation state of N atom in silver nitrate is + 5. Only option (5) is correct.

P. Kernite (Na₂B₄O₇•4H₂O) is the mineral of boron. Q. There are two isotopic forms of boron 10B (19%) and 11B (81%). R. Boron (2427 KJ/mol) has the higher second ionisation enthalpy than aluminium (1816 KJ/mol).

Raney nickel, which is very finely divided nickel powder, is a catalyst for the addition of hydrogen across C=C and C≡C bonds.

K₂[HgI₄] is Nessler’s reagent. Calgon is Na₄(PO₃)₆.

Caro’s acid is monobasic on account of the presence of one replaceable hydrogen atom.

Yes, all have no unpaired electrons, hence all are colourless.

P. The melting and boiling points of gallium are 29.8^oC and 2204^oC whereas the melting and boiling points of indium are 156^oC and 2072^oC respectively. Q. Tusionite is a rare colourless to transparent to translucent yellow brown trigonal borate mineral with chemical formula- MnSn(BO₃)₂. The mineral is composed of 18.86% manganese, 40.76% tin, 7.42% boron, and 32.96% oxygen. R. Gallium and its derivatives have only found applications in recent decades. Gallium arsenide has been used in semiconductors, in amplifiers, in solar cells (for example in satellites) and in the manufacturing of tunnel diodes for FM transmitter circuits.

Gallium (Ga) is metal with melting point of 29.8˚C. So, it remains in liquid form at nearly ambient temperature.

Turquoise (AlPO₄.Al(OH)₃.H₂O) is the mineral of aluminium. Lithopone is a mixture of ZnS and BaSO₄. It is a brilliantly white fine powder and has a tendency to turn grey on exposure to the sunlight. Talc is a pure magnesium silicate in the form of 3MgO.4SiO₂.H₂O found naturally in soap stones. Diaspore (Al₂O₃.H₂O) is the mineral of aluminium. Hence, the correct sequence of codes is P - 2, Q - 1, R - 3, S - 4.

Yes, the substances which are strongly attracted by magnetic field and show permanent magnetism even in the absence of a magnetic field are ferromagnetic. For example: Fe, Co, Ni, etc.

Both ii and iv are matched correctly. Lindlar’s catalyst: Pd/BaSO₄ Ziegler Natta catalyst: TiCl₄ + (C₂H₅)₃Al

Crooks’ glass is a special type of glass containing cerium oxide. It does not allow the passage of ultraviolet rays and used for making lenses.

Yes, it is the correct answer. P. Decaborane-14 has ten boron atoms. This number is two short of being able to form a regular icosahedron geometry. Orthocarborane (B₁₀C₂H₁₀R₂) has 12 corners and 20 faces and has regular icosahedron geometry. Q. [SiF₆]^2– is known whereas [SiCl₆]^2– not. The main reasons are :(i) six large chloride ions cannot be accommodated around Si⁴⁺ due to limitation of its size. (ii) interaction between lone pair of chloride ion and Si⁴⁺ is not very strong. R. p-Type semiconductors are made by the doping of Si atoms in group 15 elements and n-Type semiconductors are made by the doping of Si atoms in group 13 elements.