226)'Carbon dioxide cycle' implies that
the carbon dioxide structure is cyclic ocygen is changed into carbon dioxide by respiration of human beings and then to oxygen and carbon dioxide by green plants
the carbon dioxide consumes oxygen carbon dioxide moves in the air in a cycle
Answer :

227)Soda bicarbonate is useful as a fire extinguisher because
it decomposes on heating to give carbon dioxide, which extinguishes fires it releases water which extinguishes fires
it serves as a blanket for fires it emits a foam which extinguishes fires
Answer :

228)It is dangerous to have coal or charcoal burning in a closed room because
burning consumes all the oxygen and breathing becomes difficult the amount of heat produces is intolerable
there is serious risk of fire it produces the poisonous gas carbon monoxide
Answer :

229)The pair of bases in natural nucleic acids which are held by hydrogen bonds is
guanine and thymine guanine and cytosine
adenine and thymine uracil and thymine
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230)Though the temperature inside lighted electric bulb is arounf 27000C, the filament does not burn because
it does not burn in closed system it is made of non-metallic substance
the oxygen necessary for combustion (and burning) is not available as the bulb is evacuated and filled with pure nitrogen of inert gas the metal of which it is made is resistant to burning
Answer :

231)Steel contains
5 - 10% carbon 20% carbom
no carbon 0.1 - 2% carbon
Answer :

232)Saliva hydrolyses strach to
glucose fructose
sucrose carbon dioxide and water
Answer :

233)In the process of respiration, the component of air used is
oxygen nitrogen
carbon dioxide inert gases
Answer :

234)Allugel tablets used to reduce acidity contain
sodium carbonate sodium hydroxide
aluminium hydroxide magnesium hydroxide
Answer :

235)The main use of salt in the diet is to
make the taste of food better produce in small amount the hydrochloric acid required for the digestion of food
increase the solubility of food particles in water ease the process of cooking
Answer :

236)The metal most abundantly used by man is
copper gold
iron aluminium
Answer :

237)A balanced fertiliser for plants is
compost urea
super phosphate super phosphate of lime
Answer :

238)A codon
may have more than one meaning depending upon its location in the mRNA polymer helps position in the new amino acids correctly by hydrogen bonding with an anticodon of tRNA
signals that three particular amino acids be incorporated into a growing peptide is a sequence of four bases in a row
Answer :

239)The human body contains the maximum amount of
proteins fats
plasma water
Answer :

240)Anaemic patients are deficient in
calcium iodine
iron magnesium
Answer :

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