- Select the correct statement from the following option.
(a) Conjugate effect is stronger than (-I) effect
(b) Conjugate effect is weaker than (-I) effect
(c) Conjugate effect is same as (-I) effect
(d) None of the mentioned
Answer: (a)
Explanation
When the substituents like -OH have an unshared pair of electrons, the resonance effect is stronger than the inductive effect which make these substituents stronger activators, since this resonance effect direct the electron toward the ring. - which one is not isomer of butanone?
(a) 2,3-epoxybutane
(b) ethyl vinyl ether
(c) 1,2-butanol
(d) ter-butyl ether
Answer: (d)
43.larger the number of hyperconjugation structures, the stability of free radicals will __
(a) Increase
(b) Decrease
(c) Remains same
(d) None of the mentioned
Answer: (a)
44. Molisch test is used for __
(a) Lipids
(b) Proteins
(c) Carbohydrates
(d) Flavoproteins
Answer: (c)
Explanation
Molisch’s test is a chemical test which is used to check for the presence of carbohydrates in a given analyte. This test is named after Czech-Austrian botanist Hans Molisch, who is credited with its discovery. Molisch’s test involves the addition of Molisch’s reagent (a solution of α-naphthol in ethanol) to the analyte and the subsequent addition of a few drops of concentrated H2SO4 (sulphuric acid) to the mixture.
The formation of a purple or a purplish-red ring at the point of contact between the H2SO4 and the analyte + Molisch’s reagent mixture confirms the presence of carbohydrates in the analyte.
- Absorbance at 280nm is exhibited by proteins is due to
(a) aliphatic amino acids
(b) aromatic amino acids
(c) all amino acids
(d) none of these
Answer: (b)
Explanation
Proteins primarily absorb UV light due to the presence of tryptophan, tyrosine, and phenylalanine residues, with absorbance maxima at 280, 275, and 258 nm, respectively. - The compound does not contain the phosphate group, is?
(a) Nucleotide
(b) Nucleoside
(c) Both A & B
(d) None of these
Answer: (b)
47- Phosphate group is attached to which carbon of pentose sugar?
(a) C-1
(b) C-2
(c) C-4
(d) C-5
Answer: (d)
- If electricity is passed through a CuSO4 solution by using a Pt electrode then which of the following possible change occurs?
(a) H2 is deposited at the cathode
(b) Colour of the solution becomes fade
(c) Cu is deposited at an anode
(d) All are possible
Answer: (b)
Explanation
The blue colour of aqueous copper sulphate fades when it is electrolysed using platinum electrodes.
in the aqueous solution, copper sulphate dissociates into its respective ions. On passing electric current, the copper ions (cations) move towards the cathode and get deposited as copper. Simultaneously, the sulphate ions (anions) move towards the anode. So, blue colour of the solution disappears. - The degree of dissociation of week electrolyte increases as
(a) Pressure Increases
(b) Dilution decreases
(c) Dilution increases
(d) None
Answer: (c)
Explanation
When more amount of solvent is added to the solution, it helps in dissociating the molecules into ions of a weak electrolyte. Thus, degree of dissociation of weak electrolyte increases upon dilution. - What is the pH of HCl solution when the hydrogen gas electrode shows a potential of -0.22 V at standard temperature and pressure?
(a) 2.17
(b) 2.98
(c) 3.73
(d) 3.14
Answer: (c)
Explanation
Given,
potential of hydrogen gas electrode = -0.22 V Electrode reaction: H+ + e– → 0.5 H2 Applying Nernst equation, E(H+/H₂) = E°(H+/H2) – 0.059 log (1/ [H+]) E°(H+/H₂) = 0 for hydrogen gas electrode -0.22 = 0.059 log H+ -0.22 = -0.059pH pH= 3.73. - Which among the following reagent can be used to distinguish between CH2CHC≡CH from CH3CH≡CCH3??
(a) Br2/CCl4
(b) cold KMnO4
(c) Ammonical AgNO3
(d) Ag(NH3)2OH
Answer: (c) - Ethane is obtained by electrolyzing _
(a) Potassium formate
(b) Potassium succinate
(c) Potassium acetate
(d) Potassium fumarate
Answer: (c)
Explanation
This is an example of Kolbe’s electrolysis. Ethane is obtained on electrolysis of potassium acetate. - Most of the explosions in the mines in due to
(a) methane and air
(b) oxygen with acetylene
(c) hydrogen with oxygen
(d) none of these
Answer: (a) - Which statement is not true?
(a) Alkanes undergo only substitution reactions
(b) Alkenes and alkynes undergo both substitution and addition reactions
(c) Alkanes undergo both substitution and addition reactions
(d) none of these
Answer: (c)
Explanation
Alkenes and alkynes are unsaturated – they have π-bonds, so don’t have the full number of hydrogen that they could have.
This means that they are more unstable than alkanes, since π-bonds aren’t as strong as σ-bonds. The alkenes and alkynes want to form more σ-bonds and have a structure more like an alkane, so they undergo addition reactions.
Addition reactions are where more atoms are added to the molecule, not swapped or taken away. This means that the π-bonds have to be taken away and used as σ-bonds with the new atoms, rather than the σ-bonds already there being reattached – it’s easier to break π than σ.
Alkanes do not undergo this reaction because they already only have single σ-bonds, and so they cannot become more stable or stronger structurally – they are already at the peak, and so can only swap things around in substitution reactions.
55. Highest pH will be recorded for which of the following solutions if they are equimolar
(a) AlCl3
(b) LiCl
(c) BeCl2
(d) BaCl2
Answer: (d)
Explanation
AlCl3 is made up of AlOH3 and HCl.
LiCl is made up of LiOH and HCl.
BeCl2 is made up of BeOH2 and HCl.
BaOH2 is strongest base among the given options thus have maximum pH.
56. On increasing the concentration of reactants in a reversible reaction, then equilibrium constant will
(a) depend on the concentration
(b) increase
(c) unchanged
(d) decrease
Answer: (c)
Explanation
Increase in conc. of reactants will proceed the equilibrium in the forward direction giving more products. So that the equilibrium constant value remains constant and independent of concentration.
The magnitude of the equilibrium constant is not affected by the changes in concentrations of reactants and products. Hence, for a reversible reaction, if the concentrations of the reactants are doubled, then the equilibrium constant value remains the same.
- The pH of 10-3 mol dm-3 of an aqueous solution of H2SO4 is
(a) 3
(b) 2.7
(c) 2
(d) 1.5
Answer: (b)
Explanation
According the equation
H2SO4 —-> 2H^+ + SO4^-2 H2SO4[10^-3]
would ionize completely and produce 2 multiply H^+[10^-3] That is when apply PH means negative log of that value it will give 2.67. - The average rate and instantaneous rate of a reaction are equal
(a) at the start
(b) at the end
(c) in the middle
(d) when two rates have a time interval equal to zero
Answer: (d)
Explanation
rav = Δx/ Δt
rinst = dx/dt
For rav=rinst, Δt→0 i.e. the interval becomes infinitesimally small . Thus, rinst i.e., (dx/ dt )= Δt→0 lim Δx/ Δt - Consider the equilibrium system:, 2ICl(s) <—-> I2(s) + Cl2(g), Which of the following changes will increase the total amount of of Cl2 that can be produced??
(a) removing the Cl2 as it is formed
(b) adding more ICl(s)
(c) removing some of the I2(s)
(d) all of the above
Answer: (d) - Total number of nodes for 3d orbital is _
(a) 3
(b) 2
(c) 1
(d) 0
Answer: (b)
Explanation
Total number of nodes include angular and radial nodes. Angular nodes and radial nodes are given by the formula n – l -1 and l respectively. So the total number of nodes are n – l -1 + l = n – 1. For 3d orbit, “n” is 3, so total number nodes is 3 – 1 = 2.
