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11.

In a hydrogen-oxygen fuel cell, combustion of hydrogen occurs to :

A) Produce high purity water

B) Create potential difference between the two electrodes

C) Generate heat

D) Remove adsorbed oxygen from electrode surfaces

12.

Phosphine is generally prepared in the laboratory:

A) By heating phosphorus in a current of hydrogenBy heating white phosphorus with an aqueous solution ofcaustic potash

B) By heating white phosphorus with an aqueous solution of caustic potash

C) By decomposition of $P_{2}H_{4}$ at 110&#176;C

D) By heating red phosphorus with an aqueous solution of caustic soda

13.

The uncertainty in position and velocity, of a particle, are 10-10m and 5.27 x 10-24 ms-1 respectively. Calculate the mass of the particle is (h =[ 6.625 x 10-34 Js)

A) 0.099kg

B) 0.99kg

C) 0.92kg

D) None

14.

Calculate the energy needed to convert three moles of sodium atoms in the gaseous state to sodium ions. The ionization energy of sodium is 495 kJ/mol

A) 1485kJ

B) 495kJ

C) 148.5kJ

D) None of these

15.

The rate constant is doubled when the temperature increases from 27°C to 37°C. Activation energy in kJ is

A) 34

B) 54

C) 100

D) 50

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