31.

In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with

• Copper (I) sulphide (Cu₂S)

• sulphur dioxide (SO₂)

• Iron sulphide (FeS)

• Iron sulphide (FeS)

Identify the alloy containing a non-metal as a constituent in it.

• Invar

• Steel

• Bell metal

• Bell metal

The ease of adsorption of the hydrated alkali metal ions on an ion exchange resins follows the order

• Li⁺ > K⁺ >Na⁺> Rb⁺
  

• Rb⁺ < K⁺ < Na⁺ < Li⁺

• K⁺ >Na⁺>  Rb⁺ > Li⁺

• K⁺ >Na⁺>  Rb⁺ > Li⁺

Which of the following statements is not valid for oxoacids of phosphorus? 

• Orthophosphoric acid is used in the manufacture of triple superphosphate

• Hypophosphorous acid is a diprotic acid

• All oxoacids contain tetrahedral four coordinated phosphorus

• All oxoacids contain tetrahedral four coordinated phosphorus

The protecting power of lyophilic colloidal sol is expressed in terms of 

• Coagulation value

• Gold number

• Critical micelle concentration

• Critical micelle concentration

Which of the following acids does not exhibit optical isomerism?

• Maleic acid

• α-amino acids

• Lactic acid

• Lactic acid

Limiting molar conductivity  of NH₄OH (i.e.,  is equal to 

Which one of the following is an outer orbital complex and exhibits paramagnetic behaviour?

• [Ni(NH₃)₆]²⁺

• [Zn(NH₃)₆]²⁺

• [Cr(NH₃)₆]³⁺

• [Cr(NH₃)₆]³⁺

Which one of the following statement is incorrect about enzyme catalysis?

• Enzymes are mostly proteinous in nature

• Enzyme action is specific

• Enzymes are denaturated by ultraviolet rays and at high temperature

• Enzymes are denaturated by ultraviolet rays and at high temperature

Deficiency of vitamin B₁ causes the disease

• convulsions

• beri-beri

• cheilosis

• cheilosis