171. Sodium is stored in Kerosene to prevent-
oxidation.
172. Permanent
hardness is due to the presence of sulphates and chlorides of calcium and
magnesium. It can be removed by –
Adding
washing soda or by distillation
173. NPK
mixtures are fertilizers with the mixtures of –
nitrogen,
phosphorous and potassium.
174. The gas responsible
for the Bhopal Gas Tragedy is –
Methyl
Isocyanate (MIC)
175. CO2 is
used as-
fire extinguishers.
176.Thorium
is extracted from –
monozite
sand.
177. Red
phosphorus is used in :
Making matches
178. In a dry
cell, zinc and carbon act as-
electrodes.
179. Chlorine
is used as a-
bleaching agent.
180. Lead pencils contain –
graphite.
181. White phosphorus is a –
strong
poison.
182.
Carborundum is used as an abrasive for-
cutting and grinding glasses.
183. Silver
iodide is used to make –
artificial
rain.
184. Zinc
oxide is called the-
'flower of Zinc"
185. Water is
called –
'Universal
Solvent"
186. The gas
used in refrigerators is-
ammonia.
187. The lightest substance known is Hydrogen
and the heaviest is –
Osmium.
188. Con.
Nitric acid is used to-
purify gold.
189. A
mixture of salt and ice gives a temperature below 0°c which is
called Antifreeze. It is used to –
breakdown
ice mixtures in the radiators of cars in cold countries.
190. Neoprene
is a synthetic rubber used as insulators in-
Electric cables.
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