NCERT Class 12 Chemistry Gk Questions & Answers

NCERT Class 12 Chemistry Gk Questions & Answers NCERT Class 12 Chemistry QUESTIONS

NCERT Class 12 Chemistry Gk Questions & Answers

11 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
12 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
13 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
14 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
15 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
16 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.
17 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.
18 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.
19 The rate of first order reaction is 0.04 mol L-1 s-1 at 10 sec. and 0.03 mol L-1 at 2C seconds after initiation of the reaction. t1/2 of reaction is
A 24.1 s
B 34.1 s
C 44.1 s
D 54.1 s

Answer: 24.1 s
20 Which of the following statements about the catalyst is true?
A A catalyst accelerates the rate of reaction by bringing down the activation energy.
B A catalyst makes equilibrium constant more favourable for forward reaction.
C A catalyst does not participate in reaction mechanism.
D A catalyst makes the reaction feasible by making ∆G more negative.

Answer: A catalyst accelerates the rate of reaction by bringing down the activation energy.

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