(c) Salts are brittle
     (d) Salts conduct electricity when dissolved in water or even in the molten state
Ans: (b)
270. Which among the following statements with regard to pH scale is/are correct?
     1) It is a logarithmic scale
     2) The scale is limited to 0-14 because the ionic product of water isabout10-14
     3) The lower the value of pH the greater is the acidity of the solution
     Select the correct answer using the code given below: [NDA 2010]
     (a) 1 and 2
     (b) 1, 2 and 3
     (c) 1 and 3
     (d) 2 only
Ans: (b)
271. Which among the following is/are the reasons behind using Mercury in thermometers?
     1) Mercury does not wet the inner sides of the thermometer.
     2) It can be seen easily in a thin capillary tube of the thermometer.
     3) It is a good conductor of heat.
     4) It is non-toxic.
     Select the correct answer using the code given below [Asstt Commt 2010]
     (a) 1 only
     (b) 1 and 2 only
     (c) 1, 2 and 3
     (d) 3 and 4
Ans: (c)
272. The elements of a group in the periodic table [CDS 2012]
     (a) have similar chemical properties
     (b) have consecutive atomic numbers
     (c) are isobars
     (d) are isotopes
Ans: (b)
273. Which one among the following polymers is used for making bulletproof material? [CDS 2012]
     (a) Polyvinyl chloride
     (b) Polystyrene
     (c) Polyethylene
     (d) Polyamide
Ans: (c)
274. The pH of fresh groundwater slightly decreases upon exposure to air because [CDS 2012]
     (a) carbon dioxide from air is dissolved in the water
     (b) oxygen from air is dissolved in the water
     (c) the dissolved carbon dioxide of the groundwater escapes into air
     (d) the dissolved oxygen of the groundwater escapes into air
Ans: (a)
275. Which one among the following statements is correct? [CDS 2012]
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