NCERT Class 12 Chemistry Entrance Exams Questions and Answers
71 The half life of the first order reaction having rate constant K = 1.7 x 10-5s-1 is
Answer: 11.3 h
72 For a chemical reaction A→B, it is found that the rate of reaction doubles when the concentration of A is increased four times. The order of reaction is
73 Which of the following aqueous solutions should have the highest boiling point?
Answer: 1.0 M Na2SO4
74 Considering the formation, breaking and strength of hydrogen bond, predict which of the following mixtures will show a positive deviation from Raoult’s law?
Answer: Methanol and acetone.
76 Each polypeptide in a protein has aminoacids linked with each other in a specific sequence. This sequence of amino acids is said to be __________ .
Answer: primary structure of proteins.
77 Which of the following reactions of glucose can be explained only by its cyclic structure? [NCERT Exemplar]
Answer: Pentaacetate of glucose does not react with hydroxylamine.
78 Low concentration of oxygen in the blood and tissues of people living at high altitude is due to _________ .
Answer: low atmospheric pressure
79 Activation energy of a chemical reaction can be determined by __________ .
Answer: determining the rate constants at two temperatures.
80 A first order reaction is 50% completed in 1.26 × 1014 s. How much time would it take for 100% completion?