Option “B” is correct Hydro electricity is often known as White coal.
142. What is the most commonly used substance is fluorescent tubes?
1. Sodium oxide and Argon
2. Sodium vapour and Neon
3. Mercury vapour and Argon
4. Mercury oxide and Neon
Option “C” is correct A fluorescent lamp or fluorescent tube is a gas discharge lamp that uses electricity to excite mercury vapour. It contains Mercury Vapour and Argon.
143. Which is the most abundant element after Oxygen?
1. Silicon
2. Carbon
3. Sodium
4. Chlorine
Option “A” is correct The most abundant element on earth’s surface after Oxygen is Silicon. It was discovered by J.J. Berzelius in 1824. The word ‘Silicon’ was taken from the Latin word silex. Silicon chips are used as a semiconductor in computers.
144. Which of the following alloys has a maximum percentage of Copper?
1. Brass
2. Bronze
3. German Silver
4. Delta Metal
Option “B” is correct Brass consists 68–71% Copper and rest is Zinc. Bronze consists 88% Copper and 12% Tin. German silver has almost 50% Copper. Delta consists 60% Copper, 38% Zinc,2% Fe.
145. Which metal exists as a common component in Brass, Bronze and German Silver?
1. Antimony
2. Copper
3. Tin
4. Zinc
Option “B” is correct Brass consists 68-71% Copper and rest is Zinc. Bronze consists 88% Copper and 12% Tin. German silver has almost 50% Copper. Gunmetal consists 85% Copper, 5% Tin, 5% Lead, 5% Zinc.
146. What is the mass number of an element, the atom of which contains two protons, two neutrons and two electrons?
1. 2
2. 4
3. 6
4. 8
Option “B” is correct The mass number of an element is the sum of a total number of protons and neutrons inside in its nucleus and represents by A. Therefore, mass number A = number of proton+number of neutron. Therefore, mass number = 2 + 2 = 4
147. Pasteurization is a process by which-
1. Milk is preserved at a very low temperature for 24 hours
2. Milk is heated for 8 hours
3. First milk is heated up to a longer time and then cooled suddenly within specified time
4. None of these
Option “C” is correct In order to pasteurize milk, first, the milk is heated up to a longer time and then cooled suddenly within specified time. Pasteurization is a process invented the by French Scientist Louis Pasteur during the nineteenth century.
148. Which is the purest form of water?
1. Tap water
2. Sea water
3. Rainwater
4. Distilled water
Option “C” is correct Rainwater is purest form of water. Its pH value is 7.
149. The property of a substance to absorb moisture from the air on exposure is called-
Option “B” is correct Deliquescence is the process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water and forms a solution.
Option “A” is correct A group of gypsum cement, essentially hemihydrated Calcium Sulphate (CaSO4. 1/2 H2O), a white powder that forms a paste when it is mixed with water and then hardens into a solid used in making a cast, mould and sculpture.
