Chemistry Test 31

Both 0.15 M urea and 0.15 M glucose are non-electrolytes. Hence, equimolar solutions of both these substances will have equal number of particles and will exhibit the same change in their colligative properties.

Hence, they have the same atmospheric pressure and are isotonic.

Oxides of Be and Al are amphoteric in nature. Their carbides give methane on treatment with water.

Hence, the statements (B) and (D) are incorrect.

According to Hardy-Schulze law, the greater the valency of the active ion, the greater is the power to cause coagulation or coagulating power. 

Since FeCl₃ is a positively charged sol, the active ion in the electrolyte is the cation.

One mole of K₃[Fe(CN)₆] will produce 3 moles of K⁺ ions in the solution and hence, it has the highest coagulating power.

Thermosetting polymers: These polymers are cross-linked or heavily branched molecules which, on heating, undergo extensive cross linking in moulds and again become infusible. They cannot be reused. Some common examples are bakelite, urea-formaldelyde resins (UFR) etc. Melamine resin is a thermosetting polymer and is used in the making of worktop surfaces. Duroplast is a thermosetting polymer which is light in weight. It is used for making car parts. 

Hence, melamine resin and duroplast are thermosetting polymers.

Solvolysis of 3-methyl-3-bromohexane does not involve inversion of configuration.

The reaction will proceed by SN¹ mechanism through the formation of a 3^o carbocation intermediate. Hence, the statement 1 is correct.

Since the positively charged carbon atom is sp² hybridised and the mechanism is favoured by polar solvents, the statements 2 and 3 are also correct.

However, since the substrate is optically active, SN¹ mechanism will cause racemisation. Hence, option 4 is incorrect. Inversion of configuration takes place during the SN² mechanism.

Detergents can be made biodegradable and pollution free by taking unbranched hydrocarbon chains because unbranched hydrocarbons are soft and biodegradable, whereas branched hydrocarbons are hard and non-biodegradable.