Q. No.CO2 is used as a fire extinguisher because -
1. has high lattice energy.
2. will be effective in isolating the burning surface from dihydrogen and dioxygen.
3. is lighter than dioxygen.
4. is lighter than dihydrogen.
The term ’auto-protolysis’ of water means :
| 1. | Physical reaction in which two water molecules react to produce a hydroxide ion (OH–) and a hydronium ion (). |
| 2. | Chemical reaction in which five water molecules react to produce a hydroxide ion (OH–) and a hydronium ion (). |
| 3. | Chemical reaction in which two water molecules react to produce a hydroxide ion (OH–) and a hydronium ion (). |
| 4. | Chemical reaction in which two water molecules react to produce three hydroxide ions (OH–) |
The correct statement about the reaction of water with fluorine is:
| 1. | O is reduced from 0 to -1 oxidation state, whereas F is oxidized from –2 to 0 |
| 2. | F is reduced from 0 to -1 oxidation state, whereas O is oxidized from –2 to 0 |
| 3. | F is reduced from 0 to –2 oxidation state, whereas O is oxidized from – 2 to -1 |
| 4. | O is reduced from 0 to –2 oxidation state, whereas F is oxidized from –3 to 0 |
The structure of the common form of ice is :
| 1. | Each hydrogen atom is surrounded tetrahedrally by four other oxygen atoms at a distance of 540 pm. |
| 2. | Each hydrogen atom is surrounded tetrahedrally by four other oxygen atoms at a distance of 276 pm. |
| 3. | Each oxygen atom is surrounded tetrahedrally by four other oxygen atoms at a distance of 276 pm. |
| 4. | Each oxygen atom is surrounded tetrahedrally by four other oxygen atoms at a distance of 540 pm. |
The softening of hard water by synthetic ion-exchange resins is based on -
1. Increasing the lattice energy.
2. Physical separation.
3. Lowering the activation energy.
4. Exchange of cations and anions.
Water acts as a base in -
1. Reaction with
2. Reaction with
3. Reaction with NaOH
4. All of the above
‘Demineralised’ water can be obtained by :
| 1. | Passing water successively through an anion exchange (in the K+ form) and cation exchange (in the Mn- form) resin |
| 2. | Passing water successively through a cation exchange (in the H+ form) and an anion exchange (in the OH- form) resin |
| 3. | Passing water successively through an anion exchange (in the O+ form) and cation exchange (in the OH- form) resin |
| 4. | Passing water successively through a cation exchange (in the OH- form) and an anion exchange (in the H+ form) resin |
Demineralized or distilled water is not useful for drinking purposes because -
1. Demineralised water contains all insoluble minerals.
2. Demineralised water is free of all soluble minerals.
3. Demineralised water contains soluble minerals.
4. Demineralised water contains soluble anion only.
Water is important in the biosphere and biological systems because :
| 1. | It constitutes around 65% of the human body and 95% of plants |
| 2. | It acts as a carrier of various nutrients required by plants and animals for various metabolic reactions. |
| 3. | The high heat of vaporization and heat of capacity of water helps in moderating the climate and body temperature of all living beings |
| 4. | All of the above. |
The properties of water which make it useful as a solvent is/are -
1. A high value of dielectric constant
2. A high value of dipole moment
3. A high value of lattice energy
4. Both '1' and '2'
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