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CBSE Class 12 Chemistry Quiz | CBSE Class 12 Chemistry Objective Type Questions with Answers

121 Which one of the following metals is required as cofactor by all enzymes utilizing ATP in phosphate transfer?
[A] Mg
[B] He
[C] K
[D] Ca
Answer: Mg
122 Which of the following polymer is stored in the liver of animals?
[A] Glycogen
[B] Amylopectin
[C] Amylose
[D] Cellulose
Answer: slope of velocity-time graph

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123 Which of the following acids is a vitamin?
[A] Ascorbic acid
[B] Adipic acid
[C] Aspartic acid
[D] Saccharic acid
Answer: Ascorbic acid
124 Each polypeptide in a protein has aminoacids linked with each other in a specific sequence. This sequence of amino acids is said to be __________ .
[A] primary structure of proteins.
[B] secondary structure of proteins.
[C] tertiary structure of proteins.
[D] quaternary structure of proteins.
Answer: primary structure of proteins.
125 Which of the following reactions of glucose can be explained only by its cyclic structure? [NCERT Exemplar]
[A] Pentaacetate of glucose does not react with hydroxylamine.
[B] Glucose is oxidised by nitric acid to gluconic acid.
[C] Glucose forms pentaacetate.
[D] Glucose reacts with hydroxylamine to form an oxime.
Answer: Pentaacetate of glucose does not react with hydroxylamine.
126 The sugar present in milk is
[A] lactose
[B] Glucose
[C] Sucrose
[D] Maltose
Answer: lactose
127 Which of the following has magnesium?
[A] Vitamin B12
[B] Chlorophll
[C] Haemocyanin
[D] Carbonic anhydrate
Answer: Chlorophll
128 Trunbull’s blue is
[A] Ferrous ferricyanide
[B] Fe3[Fe(CN)6]4
[C] Ferrous cyanide
[D] Ferricyanide
Answer: Ferrous ferricyanide
129 Among the ligands NH3, en, CN and CO, the correct order of field strength is
[A] NH3 < en < CN– < CO
[B] CN– < NH3 < CO < en
[C] en < CN–< NH3 < CO
[D] CO < NH3 < en < CN–
Answer: NH3 < en < CN– < CO
130 Transistion metals, despite high E° oxidation, are poor reducing agents. The incorrect reason is
[A] complex forming nature.
[B] low heats of hydration.
[C] high ionization energies.
[D] high heat of vaporization.
Answer: complex forming nature.
131 Which of the following is incorrect for KMnO4 to be used as an oxidising agent?
[A] The number of electrons involved in oxidation of KMnO4 in acidic medium is 3.
[B] The equivalent weight of KMnO4 in basic medium is 158.
[C] Nitric acid is not used for the above purpose because it itself acts as a self oxidising agent and will react with the reducing agent.
[D] HCl cannot be used because some KMnO4 is consumed in the reaction.
Answer: The number of electrons involved in oxidation of KMnO4 in acidic medium is 3.
132 The property which is not characteristic of transistion metals is
[A] natural radioactivity.
[B] formation of coloured compounds.
[C] tendency to form complexes.
[D] variable oxidation states.
Answer: natural radioactivity.
133 Which one of the following characteristics of the transistion metals is associated with higher catalytic activity?
[A] Colour of hydrate ions
[B] Variable oxidation states
[C] Paramagnetic behaviour
[D] High enthalpy of atomisation
Answer: Variable oxidation states
134 Which of the following are d-block elements but not regarded as transistion elements?
[A] Zn, Cd, Hg
[B] Ru, Rh, Pd
[C] Fe, Co, Ni
[D] Cu, Ag, Au
Answer: Zn, Cd, Hg
135 Anomalous electronic configuration in the 3d series are of
[A] Cr and Cu
[B] Fe and Cu
[C] Cr and Fe
[D] Cu and Zn
Answer: Cr and Cu
136 The increasing order of reducing power of the halogen acids is
[A] HF < HCl < HBr < HI
[B] HCl < HBr < HF < HI
[C] HI < HBr < HCl < HF
[D] HBr < HCl < HF < HI
Answer: HF < HCl < HBr < HI
137 Helium is preferred to be used in balloons instead of hydrogen because it is
[A] incombustible
[B] non polarizable
[C] lighter than hydrogen
[D] more abundant than hydrogen
Answer: incombustible
138 H2S is more acidic than H2O because
[A] oxygen is more electronegative than sulphur.
[B] atomic number of sulphur is higher than oxygen.
[C] H — S bond dissociation energy is less as compared to H — O bond.
[D] H — O bond dissociation energy is less also compared to H — S bond.
Answer: atomic number of sulphur is higher than oxygen.
139 When Cl2 reacts with hot and cone. NaOH, the oxidation number of chlorine changes from
[A] zero to +1 and zero to +5
[B] 0 to -1 and 0 to +5
[C] zero to -1 and zero to +3
[D] 0 to +1 and 0 to -3
Answer: 0 to -1 and 0 to +5
140 Fluorine differs from rest of the halogens in some of its properties. This is due to
[A] its smaller size and high electronegativity.
[B] lack of d-orbitals.
[C] low bond dissociation energy.
[D] All of the these.
Answer: lack of d-orbitals.

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