31.

Use of chlorofluoro carbons is not encouraged because

• they are harmful to the eyes of people that use it

• they damage the refrigerators and air conditioners

• they eat away the ozone in the atmosphere

• they destroy the oxygen layer

Which of these does not influence the rate of reaction?

• Nature of the reactants

• Concentration of the reactants

• Temperature of the reaction

• Molecularity of the reaction

For the reaction A + B → C,it is found that doubling the concentration of A increases the rate by 4 times, and doubling the concentration of B doubles the reaction rate. What is the overall order of the reaction?

• 4

• 3/2

• 3

• 1

Gold is extracted by hydrometallurgical process, based on its property

• of being electropositive

• of being less reactive

• to form complexes which are water soluble

• to form salts which are water soluble

Which compound is zero valent metal complex?

• [Cu(NH₃)₄]SO₄

• [Pt(NH₃)₂Cl₂]

• [Ni(CO)₄]

• K₃[Fe(CN)₆]

A emulsifier is a substance which

• stabilises the emulsion

• homogenises the emulsion

• coagulates the emulsion

• accelerates the dispersion of liquid in liquid

Which of the following types of metals form the most efficient catalysts ?

• Alkali metals

• Alkaline earth metals

• Transition metals

• All of the above

The temperature of the system decreases in an

• adiabatic compression

• isothermal compression

• isothermal expansion

• adiabatic expansion

The hydrogen electrode is dipped in a solution of pH 3 at 25°C. The potential would be (the value of 2.303 RT/F is 0.059 V)

• 0.177 V

• 0.087 V

• 0.059 V

• - 0.177 V

Corrosion of iron is essentially an electrochemical phenomenon where the cell reactions are

• Fe is oxidised to Fe²⁺ and dissolved oxygen in water is reduced to OH^-.

• Fe is oxidised to Fe³⁺ and H₂O is reduced to O${}_2^{2-}$.

• Fe is oxidised to Fe²⁺ and H₂O is reduced to O${}_2^{-}$.

• Fe is oxidised to Fe²⁺ and H₂O is reduced to O₂.