Page 56 - Science Class 08

3. the term used to express purity of gold : _______________________
4. the metal whose salts are used to treat cancer : _______________________

5. helium, neon, xenon, argon and krypton : _______________________
6. substances that are non-conductorrs of electricity : _______________________
7. the substance that prevents sep c : _______________________

8. the chief metal used to make an alloy : _______________________
9. the alloy used to make magnets : _______________________
10. the metal used in thermometers : _______________________
C. Name.

1. two noble metals :
__________________ __________________
2. three stages in gold extrac on :

__________________ __________________ __________________
3. three substances with which pla num combines:
__________________ __________________ __________________
4. three metals used to make German silver:

__________________ __________________ __________________
5. five countries where pla num is mined :
__________________ __________________ __________________
__________________ __________________

6. five noble gases :
__________________ __________________ __________________
__________________ __________________
D. Match the following columns.

Column I Column II
1. Gold a. Alloy for making magnets
2. Pla num b. An sep c

3. Krypton c. Least reac ve
4. Tincture iodine d. Costliest metal
5. Alnico e. A noble gas
E. Fill in the blanks.

1. Noble metals remain _____________________ by air, water and acidic substances.
2. Gold is used as a money in the __________________ trade and exchange.
3. Pla num quickly combines with _____________________ , ______________________ and
___________________.
4. Chlorine is extracted from crude ________________ obtained from ________________ .

5. Some non-metals are kept in _____________________ for their protec on against the air.

56 Science-8