(d) oxide coating on silver
Ans: (b)
307. Which one among the following methods is not effective in removing arsenic from contaminated ground water? [NDA
     2011]
     (a) Boiling
     (b) Reverse osmosis
     (c) Ion exchange
     (d) Coagulation-adsorption
Ans: (c)
308. Bronze is often used to make statues and medals whereas brass is used in making utensils, scientific apparatus and
     cartridges. Both brass and bronze are copper containing alloys, yet they differ in their chemical composition for
     additionally containing: [NDA 2011]
     (a) Zinc in brass and tin in bronze
     (b) Chromium in brass and nickel in bronze
     (c) Nickel in brass and tin in bronze
     (d) Iron in brass and nickel in bronze
Ans: (a)
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