Chemistry - Study Mode
[#926] The gas used in the manufacture of vanaspati from vegetable oil is
Correct Answer
(A) hydrogen
Explanation
Solution: Hydrogenation - to treat with hydrogen - is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. The largest scale application of hydrogenation is for the processing of vegetable oils (fats to give margarine and related spreads and shortenings). Typical vegetable oils are derived from polyunsaturated fatty acids (containing more than one carbon-carbon double bonds). Their partial hydrogenation reduces most but not all, of these carbon-carbon double bonds. Hydrogenation converts liquid vegetable oils into solid or semi-solid fats, such as those present in margarine.
[#927] The ionic radii of N 3- , O 2- , F - and Na + follows the order
Correct Answer
(A) N 3- > O 2- > F - > Na +
Explanation
Solution: The ionic radii of N 3- , O 2- , F - and Na + follows the order
N 3- > O 2- > F - > Na +
[#928] The graphite rods in the nuclear reactor
Correct Answer
(D) convert fast moving neutrons into thermal neutrons
Explanation
Solution: In nuclear reactor graphite rods are used as moderator or controller. Application of moderator is to slow down the neutron and controller is to control the number of neutron.
[#929] Which one of the following forms of phosphorus is most reactive?
Correct Answer
(B) White phosphorus
Explanation
Solution: The white phosphorus allotrope is the most reactive, least stable and most toxic of the three. It consists of four phosphorus molecules that chemically bond to form a tetrahedral shape.
[#930] Limestone is a raw material used by which industry?
Correct Answer
(C) Cement
Explanation
Solution: Limestone is used as a raw-material for the manufacture of quicklime (calcium oxide), slaked lime (calcium hydroxide), cement and mortar. Clay and shale are also used as raw materials for the production of cement.