1. The alum used for purifying water is
a) Ferric alum
b) Chrome alum
c) Potash alum
d) Ammonium alum
Explanation: Potash alum is used for purifying water.
2. The boiling point of water is exceptionally high because
a) there is covalent bond between H and O
b) water molecule is linear
c) water molecules associate due to hydrogen bonding
d) water molecule is not linear
Explanation: The high boiling point of water is due to H-bonding
3. The H–O–H angle in water molecule is about
a) 90º
b) 180º
c) 102º
d) 105º
Explanation: The hybridisation in water is sp3 and bond angle 105º
4. When two ice cubes are pressed over each other, they unite to form one cube. Which of the following forces is responsible to hold them together ?
a) Hydrogen bond formation
b) van der Waals forces
c) Covalent attraction
d) Ionic interaction
Explanation: Two ice cubes stick to each other due to H-bonding
5. The process used for the removal of hardness of water is
a) Calgon
b) Baeyer
c) Serpeck
d) Hoope
Explanation: Calgon process is used to remove permanent hardness of water
6. Pure water can be obtained from sea water by
a) centrifugation
b) plasmolysis
c) reverse osmosis
d) sedimentation
Explanation: Sea water is purified by reverse osmosis
7. Polyphosphates are used as water softening agents because they
a) form soluble complexes with anionic species
b) precipitate anionic species
c) form soluble complexes with cationic species
d) precipitate cationic species
Explanation: Polyphosphates form soluble complexes with Ca2+ and Mg2+ and are removed.
8. What is heavy water ?
a) \[H_{2}O^{18}\]
b) \[H_{2}O^{16}\]
c) \[H_{2}O_{3}\]
d) \[D_{2}O\]
Explanation: D2O is heavy water
9. \[D_{2}O\] is used in
a) industry
b) nuclear reactor
c) medicine
d) insecticide
Explanation: D2O is used in nuclear reactors as moderators.
10. What is formed when calcium carbide reacts with heavy water?
a) \[C_{2}D_{2}\]
b) \[CaD_{2}\]
c) \[Ca_{2}D_{2}O\]
d) \[CD_{2}\]
Explanation: CaC2 + 2D2O \[\rightarrow\] C2D2 + Ca(OD)2