106)The substance most commonly used as a food preservative is
acetic acid tartaric acid
benzoic acid sodium carbonate
Answer :

107)The reagent that bleaches the colour of a fabric is
sulphur dioxide sodium chloride
carbon dioxide sulphur trioxide
Answer :

108)A chemical reaction that place with the evolution of heat is called a/an
endothermic reaction reversible reaction
exothermic reaction thermal reaction
Answer :

109)The process in which a solid substance, on being heated, changes directly into the gaseous form is known as
dissociation dissolution
evaporation sublimation
Answer :

110)The smallest possible unit of a chemical compound is
atom electron
molecule proton
Answer :

111)Silver halides are used in photographic plates because they are
colourless oxidised in air
readily reduced by light easily soluble in hypo solution
Answer :

112)Hypo, used in photography, is chemically
sodium thiosulphate silver bromide
silver nitrate sodium phosphate
Answer :

113)It is not advisable to sleep under a tree at night because trees release _______ at night
oxygen carbon dioxide
nitrogen sulphur dioxide
Answer :

114)Cinnabar is an ore of
iron copper
lead mercury
Answer :

115)The crystalline form of silica used in scientific apparatus for passing ultraviolet light is called
pyrex glass soda glass
quartz glass corning glass
Answer :

116)Camphor can easily be purified by the process of
sublimation crystallisation
sedimentation distillation
Answer :

117)The gas used for artificial ripening of green fruit is
carbon dioxide acetylene
ethane ethylene
Answer :

118)The most commonly used metal in the pure form or as an alloy in domestic appliances is
iron copper
aluminium zinc
Answer :

119)The purity of primary gold is
10 carat 16 carat
24 carat 32 carat
Answer :

120)Tetraethyl lead (TEL) is added to petrol to
increase boiling point increase flash point
prevent freezing increase anti-knocking rating
Answer :

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