Question 1

The stoichiometric reaction of 516 &#160; g of dimethyldichlorosilane with water results in a tetrameric cyclic product X in 75 % yield. The weight (in g ) of X obtained is ____________ [Use, molar ma

Accepted Answer

The dimethyldichlorosilane is  CH 3 2 SiCl 2 . The molecular mass is  129 &#160; u . Number of moles of dimethyldichlorosilane initially taken  = 516 129 = &#160; 4 moles Applying POAC on Si atom Moles of tetrameric cyclic product formed = 4 4 &#215; 75 100 = 0 . 75 &#160; moles Molar mass of product formed  = 296 &#160; g / moles The mass of product formed  = 296 &#215; 0 . 75 = 222 &#160; g

Question 2

The treatment of galena with HNO 3 produces a gas that is

Accepted Answer

Concentrated nitric acid is a strong oxidising agent and attacks most metals except noble metals such as gold and platinum. The products of oxidation depend upon the concentration of the acid, temperature and the nature of the material undergoing oxidation. PbS + dil . HNO 3 &#8594; Pb NO 3 2 + S + NO + H 2 O NO is paramagnetic due to the presence of unpaired electron. It is a neutral oxide. It is colourless. Hence, A  and D  are correct statements.

p Block Elements (Group 13 & 14) — Previous Year Questions & Solutions