WBCS Prelims – 2018
66. If we add salt to pure water, its boiling point will
(a) increase
(b) decrease
(c) remains same
(d) None of the above
140. Bleaching action of chlorine is by
(a) decomposition
(b) hydrolysis
(c) reduction
(d) oxidation
145. Chemical name of vinegar is
(a) Sodium nitrate
(b) Dilute acetic acid
(c) Chloride of lime
(d) Calcium
153. The term PVC used in plastic industry stands for
(a) Polyvinyl Chloride
(b) Polyvinyl carbonate
(c) Phosphor Vanadium Chloride
(d) Phospho Vinyl Chloride
157. Plaste of paris is produced by heating
(a) Graphite
(b) Gypsum
(c) Zinc
(d) Lead
WBCS Prelims – 2017
31. Conversion of CH3C =CH to CH3CH=CH2   
Lindlar catalyst
32. Conversion of RBr to RMgBr requires   
Mg/dry ether / N2 – atmosphere
Mg/ moist ether /N2 – atmosphere   
Mg/ ethanol /N2 -atmosphere   
Mg / dry ether /O2 – atmosphere.   
33.  The fastest SN1 reaction is of the followings:   
MeO — CH2 –Cl    
Me — CH2 -Cl   
Me –C –CH2 –Cl   
Ph — CH2 –CH2 – Cl  
41.  The strongest electropositive element is   
(A) Cs   (Cesium)
(B) Li   
(C) Mg   
(D) K   
42.  Geometry of SF4 is   
squre planar   
43.  A reaction is spontaneous when   
Delta G = -ve
Delta H = -ve   
Delta S = +ve   
Delta S = -ve   
50. The material used for safety from nuclear radiation is   
WBCS Prelims – 2016
97.  Which among the following is called ‘Laughing Gas’ popularly ?
(A) Nitric oxide       
(B) Nitrous oxide  (N2O)     
(C) Nitrogen penta oxide      
(D) Nitrogen
101.  Which among the following gas was leaked during the Bhopal gas tragedy in 1984 ?
(A) Methyl isocyanides        
(B) Methyl isocyanate      
(C) Methyl isochloride      
(D) Methyl isochlorate
108.  Which metal is present in chlorophyll ?
(A) Iron        
(B) Zinc       
(C) Aluminium        
(D) Magnesium
111.  In the manufacture of Vanaspati ghee from vegetable oils, which among the following gas is used ?
(A) Nitrogen        
(B) Carbon dioxide         
(C) Hydrogen         
(D) Neon
115.   Which among the following is responsible for depletion of Ozone layer ?
(A) Carbon monoxide      
(B) Carbon dioxide       
(C) Chlorofluoro carbon      
(D) Mercuric oxide
119.  The term PVC used in the plastic industry stands for :
(A) Phospho Vinyl Chloride        
(B) Poly Vinyl Carbonate 
(C) Poly Vinyl Chloride        
(D) Phospho Vanadium Chloride
WBCS Prelims – 2015
97.   Mg2+ is isoelectronic with
        (A) Ca2+        (B) Na+       (C) Zn2+      (D) Cu+
101.  Hybridization of C2 and C3 of
(A) sp   sp3         (B) sp2  sp        
(C) sp2   sp2       (D) sp  sp
108.  The compound that cannot be kept is glass vessel because it reacts with glass is
(A) HNO3     (B) HCl        
(C) HF         (D) HBr
111.  How many grams of NaOH are needed to make 100ml. of a 0.5 M solution of NaOH ? (Atomic weight : Na = 23, 0 = 16,  H = l)
(A) 2        (B) 20       
(C) 4       (D) 1
115.  Chemically Aspirin is :
(A) Acetyl salicylic acid     
(B) Sodium salicylate      
(C) Methyl salicylate       
(D) Ethyl salicylate
WBCS Prelims – 2014
130.  The most malleable metal is
(A) Platinum       
(B) Silver      
(C) lron       
(D) Gold
149.  The heat required to raise the temperature of a body by 1K is called
(A) Specific heat       
(B) Thermal capacity      
(C) Water equivalent      
(D) None of the above
155.  The most abundant rare gas in the atmosphere is
(A) Helium      
(B) Neon        
(C) Argon      
(D) Xenon
161.  Washing soda is the common name for
(A) Sodium carbonate   (Na2CO3)
(B) Calcium carbonate      
(C) Sodium bicarbonate      
(D) Sodium hydroxide
167.  The half-life period of an isotope is 2 hours. After 6 hours what fraction of the initial quantity of the isotope will be left behind ?
(A) 1/6        (B) 1/3        
(C) 1/8       (D) 1/4
174.  The number of electrons present in H+ is
(A) Zero       (B) One      
(C) Two        (D) Three
WBCS Prelims – 2013
48.  One of the breakthrough of Acharya P. C. Roy was to synthesize the following compound :
(A) HgCl2       
(B) HgO       
(C) Hg2Cl2       
(D) H2O4
54.  Whose presence in drinking water is welcome ?
(A) K       (B) Ca      
(C) As     (D) Fe
62.  Muriatic acid used in household work is diluted form of —
(A) Acetic acid       
(B) Hydrochloric acid      
(C) Oxalic acid      
(D) Aqua regia
69.   Which metal ion is associated with Haemoglobin ?
(A) Mg++      (B) Fe++      
(C) Al+++      (D) Mn++
72.  Phenyl used in household work is a derivative of —
(A) Methyl alcohol       
(B) Tartaric acid       
(C) Benzene     
(D) Anthracene
190.   ‘Higgs Boson’ is :
(A) Name of a film       
(B) An elementary particle      
(C) Generic name of a medicine    
(D) Planet
WBCS Prelims – 2012
155.  Calculate the shielding suffered by valence electron in fluorine
(A) 5.20      (B) 4.80      
(C) 5.80      (D) 4.85
167.  How many gms of dibasic acid (mol wt 200) should be present in 100 ml of its aqueous solution to give 0.1(N) strength ?
(A) 2 gm        (B) 1gm       
(C) 10 gm      (D) 20 gm
171.   Which one of the following is a thermoplastic polymer ?
(A) Rubber      
(B) Nylon 6-6       
(C) PVC    
(D) Bakelite
174.   Proteins are detected by
(A) Molish’s test      
(B) Biuret test      
(C) DNP test     
(D) Benedict’s test
WBCS Prelims – 2011
95.  Vulcanisation is the process of heating rubber with 3 – 5% of
(A) Sulphur      
(B) Lime      
(C) Potassium permanganate      
(D) Naphthalene
125.  Ozone depletion in Antarctica is caused by the formation of
(A) Nitrogen dioxide      
(B) Sulphur dioxide       
(C) Freon      
(D) Chlorine nitrate
138.  Brass is an alloy of
(A) Iron and Copper      
(B) Copper and Tin      
(C) Copper and Aluminium      
(D) Copper and Zinc
175.  Which pollutant of the atmosphere inhibits the Hill reaction of photosynthesis ?
(A) Per acetyl nitrate      
(B) Nitrogen monoxide      
(C) Ultra violet rays     
(D) Hydrocarbon
WBCS Prelims – 2010
42.  Which of the following is a good nuclear fuel ?
(A) Uranium 238     
(B) Plutonium 239      
(C) Neptunium 239     
(D) Thorium 236
132.  Attempt is being made to regulate vehicular pollution by autorickshaws through switching over to
(A) Petrol       
(B) Alcoholic fuel        
(C) CNG     
(D) Diesel
155.  In respiration, cytosol plays a significant role in
(A) Oxidative phosphorylation       
(B) Oxidative decarboxylation of pyruvic acid
(C) Krebs cycle       
(D) Glycolysis
WBCS Prelims – 2009
66.   Fullerene is
(A) An allotrope of carbon      
(B) A synonym for carborundum
(C) Artifical emery      
(D) A compound of carbon