Option “B” is correct The acid produced by ants is called formic acid.The name comes from the Latin word for ant, which is “formica.” Chemically, it is a simple carboxylic acid.
212. Which of the following is not a donor atom?
1. Phosphorus
2. Antimony
3. Arsenic
4. Aluminium
Option “D” is correct In semiconductor physics, a donor is a dopant atom that, when added to a semiconductor, can form a n-type region. All except aluminium are donor atom.
213. The element found maximum in the soil layer is-
1. Oxygen
2. Nitrogen
3. Manganese
4. Silicon
Option “A” is correct The element found the maximum in the soil layer is Oxygen 46.8% followed by Silicon 27.2%, Calcium 3.65% and Carbon 0.6%.
214. Which is the most reactive metal?
1. Sodium
2. Calcium
3. Iron
4. Potassium
Option “D” is correct
215. Aluminium surface is often ‘Anodized’. This means the deposition of a layer of-
Option “B” is correct Anodizing is an electrical-chemical process by which the surface of a metal is made durable and rust resistant. In this process, a layer of Aluminium Oxide is deposited on Aluminium.
216. Galvanized iron is coated with-
1. Aluminium
2. Galena
3. Silver
4. Zinc
Option “D” is correct Galvanization is the process of applying protective zinc coating to steel or iron to prevent rusting.
217. Bronze is an alloy of-
1. Copper and Tin
2. Copper and Silver
3. Copper and Iron
4. Copper and Lead
Option “A” is correct Bronze is an alloy made up of Copper and another metal Tin. Compositions may vary but most modern bronze is 88% Copper and 12% Tin.
218. Dry ice is-
1. Solid water
2. Mountain ice
3. Solid CO2
4. Solid carbon mono oxide
Option “C” is correct Dry ice sometimes referred to as solid or dry snow is the solid form of Carbon dioxide.
219. 0 K is equivalent to –
1. 273°C
2. – 273°C
3. 0°C
4. 100°C
Option “B” is correct 0 K is equivalent to – 273°C.
220. ___________ gives hardness to stainless steel.
1. Zinc
2. Lead
3. Carbon
4. Tin
Option “C” is correct Carbon gives hardness to Stainless Steel.
or dry snow is the solid form of Carbon dioxide.