The bond dissociation energies of X2, Y2 and XY are in the ratio of 1 : 0.5 : 1. ΔH for the formation of XY is – 200 kJ mol–1. The bond dissociation energy of X2 will be
a.
400 kJ mol–1
Correct Answer
b.
200 kJ mol–1
c.
800 kJ mol–1
d.
100 kJ mol–1
Step-by-Step AI Explanation
Verified Method
Reaction: 1/2 X2 + 1/2 Y2 -> XY. ΔH = [Σ BE of reactants] - [Σ BE of products] = [1/2(x) + 1/2(0.5x)] - [x] = -200. Solving this, 0.75x - x = -200 => -0.25x = -200 => x = 800 kJ/mol? Wait, recalculating: BE_X2 = x, BE_Y2 = 0.5x, BE_XY = x. ΔH = (0.5x + 0.25x) - x = -0.25x = -200. Thus, x = 800 kJ/mol.
Q2mcq
When initial concentration of the reactant is doubled, the half-life period of a zero order reaction
a.
remains unchanged
b.
is halved
c.
is tripled
d.
is doubled
Correct Answer
Step-by-Step AI Explanation
Verified Method
For a zero-order reaction, t(1/2) = [A]0 / 2k. Since t(1/2) is directly proportional to the initial concentration [A]0, doubling the concentration doubles the half-life.
Q4mcq
Which one of the following conditions will favour maximum formation of the product in the reaction, A2(g) + B2(g) ⇌ 2X2(g) ΔrH = – X kJ ?
a.
High temperature and low pressure
b.
Low temperature and high pressure
c.
High temperature and high pressure
d.
Low temperature and low pressure
Correct Answer
Step-by-Step AI Explanation
Verified Method
The reaction is exothermic (ΔH < 0), so low temperature favors the product. The number of moles of gaseous reactants (2) equals the number of moles of gaseous products (2), so pressure has no effect on the equilibrium position.
Q5mcq
For the redox reaction MnO4- + C2O4 2- + H+ -> Mn2+ + CO2 + H2O, the correct coefficients of the reactants for the balanced equation are (MnO4-, C2O4 2-, H+)
Carboxylic acids have higher boiling points than aldehydes, ketones and even alcohols of comparable molecular mass. It is due to their
a.
formation of intermolecular H-bonding
Correct Answer
b.
formation of intramolecular H-bonding
c.
more extensive association of carboxylic acid via van der Waals force of attraction
d.
formation of carboxylate ion
Step-by-Step AI Explanation
Verified Method
Carboxylic acids form stronger intermolecular hydrogen bonds (dimers) compared to alcohols and carbonyl compounds, leading to higher boiling points.
Q7mcq
Carboxylic acids have higher boiling points than aldehydes, ketones and even alcohols of comparable molecular mass. It is due to their
a.
formation of intermolecular H-bonding
Correct Answer
b.
formation of intramolecular H-bonding
c.
more extensive association of carboxylic acid via van der Waals force of attraction
d.
formation of carboxylate ion
Step-by-Step AI Explanation
Verified Method
Carboxylic acids form stronger and more extensive intermolecular hydrogen bonding (forming dimers) compared to alcohols, leading to higher boiling points.
Q9mcq
The correct difference between first- and second-order reactions is that
a.
the rate of a first-order reaction does depend on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations
b.
the rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction does depend on reactant concentrations
c.
a first-order reaction can be catalyzed; a second-order reaction cannot be catalyzed
d.
the half-life of a first-order reaction does not depend on [A]0; the half-life of a second-order reaction does depend on [A]0
Correct Answer
Step-by-Step AI Explanation
Verified Method
For a first-order reaction, t1/2 = 0.693/k, which is independent of initial concentration [A]0. For a second-order reaction, t1/2 = 1/(k[A]0), which depends on [A]0.
Q11mcq
Among CaH2, BeH2, BaH2, the order of ionic character is
a.
BaH2 < BeH2 < CaH2
b.
BeH2 < CaH2 < BaH2
Correct Answer
c.
BeH2 < BaH2 < CaH2
d.
CaH2 < BeH2 < BaH2
Step-by-Step AI Explanation
Verified Method
As the size of the alkaline earth metal cation increases down the group, the electronegativity difference between the metal and hydrogen increases, making the hydride more ionic.
Q12mcq
In which case is the number of molecules of water maximum?
a.
10^-3 mol of water
b.
18 mL of water
Correct Answer
c.
0.00224 L of water vapours at 1 atm and 273 K
d.
0.18 g of water
Step-by-Step AI Explanation
Verified Method
18 mL of water is equal to 18 g (since density is 1 g/mL), which equals 1 mole of water (~6.022 x 10^23 molecules). The other options represent much smaller quantities.
Q13mcq
The difference between amylose and amylopectin is
a.
Amylose is made up of glucose and galactose
b.
Amylopectin have 1->4 alpha-linkage and 1->6 alpha-linkage
Correct Answer
c.
Amylopectin have 1->4 alpha-linkage and 1->6 beta-linkage
d.
Amylose have 1->4 alpha-linkage and 1->6 beta-linkage
Step-by-Step AI Explanation
Verified Method
Amylose is a linear chain with 1->4 alpha-glycosidic linkages, while amylopectin is a branched polymer containing both 1->4 and 1->6 alpha-linkages.
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Magnesium reacts with an element (X) to form an ionic compound. If the ground state electronic configuration of (X) is 1s2 2s2 2p3, the simplest formula for this compound is
a.
Mg3X2
b.
Mg2X3
c.
Mg2X
d.
MgX2
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Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations: a. 60 mL 10^-1 M HCl + 40 mL 10^-1 M NaOH, b. 55 mL 10^-1 M HCl + 45 mL 10^-1 M NaOH, c. 75 mL 5 x 10^-2 M HCl + 25 mL 5 x 10^-2 M HCl, d. 100 mL 10^-1 M HCl + 100 mL 10^-1 M NaOH. pH of which one of them will be equal to 1?
a.
c
b.
b
c.
d
d.
a
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The solubility of BaSO4 in water is 2.42 x 10^-3 gL^-1 at 298 K. The value of its solubility product (Ksp) will be (Given molar mass of BaSO4 = 233 g mol^-1)
a.
1.08 x 10^-8 mol2 L^-2
b.
1.08 x 10^-10 mol2 L^-2
c.
1.08 x 10^-14 mol2 L^-2
d.
1.08 x 10^-12 mol2 L^-2
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Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is
a.
CH4
b.
CH triple bond CH
c.
CH3 - CH3
d.
CH2 = CH2
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