191. The passage of an electric current through a conducting liquid causes ___________.
1. Galvanisation
2. Evaporation
3. Physical Reaction
4. Chemical Reaction
Option “D” is correct The passage of an electric current through a conducting liquid causes Chemical Reaction.
192. Who invented Dynamite?
1. J B Dunlop
2. Alfred Nobel
3. James Simons
4. Peter Hargreaves
Option “B” is correct Dynamite is an explosive made of nitroglycerin, sorbents (such as powdered shells or clay) and stabilizers. It was invented by the Swedish chemist and engineer Alfred Nobel in Geesthacht, and patented in 1867. It rapidly gained wide-scale use as a safer alternative to black powder.
193. A radio-active substance has a half life of six months. Three-fourth of the substance will decay in ______.
1. Six months
2. Ten months
3. Twelve Months
4. Twenty four months
Option “C” is correct Half life of any radioactive substance is the amount of time required for the quantity / weight of the substance to fall to half its initial value. So after one half life, we will have ½ or 50% of the substance remaining. And after 2 half lives, we will have ¼ of the substance remaining. In other words, ¾ of the substance will take two half lives to decay. As one half life is given as 6 months, so the substance will take 12 months to decay by ¾ th quantity by weight.
194. Which is the fundamental element of all organic compounds?
1. Nitrogen
2. Oxygen
3. Carbon
4. Silicon
Option “C” is correct The organic compounds are a large class of chemical compounds in which one or more atoms of carbon are covalently linked atoms of other elements, most commonly Hydrogen, Oxygen or Nitrogen.
195. The important metal used with iron to make it rust free-
1. Aluminium
2. Carbon
3. Chromium
4. Tin
Option “C” is correct Stainless steel alloy with a minimum of 10.5% Chromium content by mass. The presence of Chromium protects steel from corrosion, rust and make it high-temperature resistance.
196. Which one of the following catalysts is used in hydrogenation of vegetable oils?
1. Zinc
2. Platinum
3. Nickel
4. Iron
Option “C” is correct During hydrogenation, the vegetable oils are reacted with hydrogen gas . A nickel catalyst is used to speed up the reaction. The double bond is converted to single bond in the reaction. In this way, the unsaturated fats can be made into saturated fats.
197. What is the shape of Sulphur hexafluoride molecule?
Option “B” is correct Sulphur hexafluoride (SF6) is an inorganic, colourless, odourless and non-flammable compound. SF6 has an octahedral shape. It has 12 electrons around the central Sulphur atom. This means there are six electron pairs arranged in an octahedral shape.
198. Which is not a Lewis acid?
1. AlCl3
2. BF3
3. NH3
4. FeCl3
Option “C” is correct The Lewis acids are lone pair acceptors. The Lewis bases are lone pair donors. Nitrogen in NH3 has 5 electrons in which 3 of them are involved in bonding. That leaves one lone pair. This lone pair is available for bonding. Therefore, NH3 is a Lewis base.
199. Formation of ozone hole is maximum over –
1. Africa
2. India
3. Antarctica
4. Europe
Option “C” is correct A continent sized hole (thinning) has been formed over Antarctica as a result of damage to ozone.
