Heavy water is:

• water containing Fe, Cr, Mn

• water at 0°C

• D₂O

• water obtained after distillation

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

• generate heat

• create potential difference between the two electrodes

• produce high purity water

• remove adsorbed oxygen from electrode surfaces

Which one of the following will dissolve in water most readily?

• I₂

• BaCO₃

• KF

• PbI₂

Heavy water is represented as

• H₂¹⁸O

• D₂O

• D₂¹⁸O

• H₂O at 4°C

The most abundant element in the universe is thought to be

• carbon

• oxygen

• hydrogen

• nitrogen

The compound that can work both as an oxidising as well as reducing agent is

• KMnO₂

• H₂O₂

• Fe₂(SO₄)₃

• K₂Cr₂O₇

67.

Which one of the following is not a method to remove permanent hardness of water?

• Clark's method

• Calgon method

• Ion- exchange method

• Synthetic resins methods

Reaction of calgon with hard water containing Ca²⁺ ions produce

• [Na₂CaP₆O₁₈]^2-

• CaCO₃

• CaSO₄

• Ca₂(PO₄)₃

Diborane (B₂H₆) reacts independently with O₂ and H₂O to produce, respectively:

• B₂O₃ and H₃BO₃

• H₃BO₃ and B₂O₃

• B₂O₃ and [BH₄]^-

• HBO₂ and H₃BO₃