Chemistry

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Reaction between benzaldehyde and acetophenone in presence of dilute NaOH is known as : Answer: 4. Cross Aldol condensation Benzaldehyde has no α -hydrogen, while acetophenone has α -hydrogens. In dilute NaOH, acetophenone forms... Alpha-hydrogen acidity, aldol, Cannizzaro, haloform 1 answer
Which of the following is not correct about carbon monoxide ? Answer: 3. The carboxyhaemoglobin (haemoglobin bound to CO) is less stable than oxyhaemoglobin. CO binds to haemoglobin to form carboxyhaemo... Electronic configuration and general trends, Group 13 and 14 1 answer
Match the following and identify the correct option.(a) CO(g) + H_2(g) (i) Mg(HCO_3)_2 + Ca(HCO_3)_2(b) Temporary hardness of water (ii) An electron deficient hydride(c) B_2H_6 (iii) Synthesis gas(d) H_2O_2 (iv) Non-planar structure Answer: 1. (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv) (a) CO+H₂ is water gas, called synthesis gas: (iii). (b) Temporary hardness is due to Mg(H... Electronic configuration and general trends, Group 13 and 14 1 answer
Measuring Zeta potential is useful in determining which property of colloidal solution ? Answer: 3. Stability of the colloidal particles Zeta potential is the potential difference between the fixed layer of charge on a colloidal... Lyophilic and lyophobic sols 1 answer
Paper chromatography is an example of : Answer: 2. Partition chromatography In paper chromatography the stationary phase is water held in the cellulose fibres of the paper, and the... Chromatography 1 answer
The number of Faradays(F) required to produce 20 g of calcium from molten CaCl_2 (Atomic mass of Ca = 40 g mol^-1) is : Answer: 1. 1 Electrode reaction: mathrmCa²⁺+2e^-→ Ca . One mole of Ca needs 2 F. Moles of Ca =20/40=0.5 mol. Charge =0.5×2=1 F. Answer: opti... Electrolytic and galvanic cells, electrode potentials 1 answer
What is the change in oxidation number of carbon in the following reaction ?CH_4(g) + 4Cl_2(g) → CCl_4(l) + 4HCl(g) Answer: 3. - 4 to +4 Find carbon's oxidation number on each side. In CH₄ : x+4(+1)=0 , so x=-4 . In CCl₄ : x+4(-1)=0 , so x=+4 . The change... Oxidation and reduction, oxidation number 1 answer
The freezing point depression constant (K_f) of benzene is 5.12 K kg mol^-1. The freezing point depression for the solution of molality 0.078 m containing a non-electrolyte solute in benzene is (rounded off upto two decimal places) : Answer: 3. 0.40 K Depression in freezing point: Δ T_f=K_f m . Δ T_f=5.12×0.078=0.399≈0.40\ K Option (3) is correct. Colligative properties 1 answer
A mixture of N_2 and Ar gases in a cylinder contains 7 g of N_2 and 8 g of Ar. If the total pressure of the mixture of the gases in the cylinder is 27 bar, the partial pressure of N_2 is :[Use atomic masses (in g mol^-1) : N = 14, Ar = 40] Answer: 3. 15 bar Partial pressure p_i=x_i P_total . Moles N₂=7/14=0.25 ; moles Ar =8/40=0.2 . x_(N_2)=0.25/0.45=5/9 . p_(N_2)=5/9×27=15 bar... Concentration terms: molality, molarity, mole fraction, percentage 1 answer
The mixture which shows positive deviation from Raoult's law is : Answer: 1. Ethanol + Acetone Positive deviation occurs when A-B attractions are weaker than A-A and B-B. Ethanol has strong hydrogen bonding... Ideal and non-ideal solutions 1 answer
Which one of the followings has maximum number of atoms ? Answer: 4. 1 g of Li(s) [Atomic mass of Li = 7] Number of atoms is proportional to moles of atoms = mass / atomic mass (all masses are 1 g).... Atomic and molecular masses, mole concept, molar mass 1 answer
The number of protons, neutrons and electrons in ^175_71Lu, respectively, are : Answer: 1. 71, 104 and 71 For ^A_ZX : protons =Z=71 ; neutrons =A-Z=175-71=104 ; electrons (neutral atom) =71 . Answer: 71, 104 and 71, opti... Matter and its nature, Dalton's atomic theory 1 answer
A tertiary butyl carbocation is more stable than a secondary butyl carbocation because of which of the following ? Answer: 4. Hyperconjugation Methyl groups attached to the positive carbon stabilise it by hyperconjugation: C-H sigma electrons delocalise i... Inductive effect, electromeric effect, resonance, hyperconjugation 1 answer
Elimination reaction of 2-Bromo-pentane to form pent-2-ene is :(a) β-Elimination reaction(b) Follows Zaitsev rule(c) Dehydrohalogenation reaction(d) Dehydration reaction Answer: 1. (a), (b), (c) 2-Bromopentane CH₃CHBrCH₂CH₂CH₃ loses HBr with alcoholic KOH. (a) H is removed from the carbon beta to the carbon b... Types of organic reactions 1 answer
Which of the following set of molecules will have zero dipole moment ? Answer: 4. Boron trifluoride, beryllium difluoride, carbon dioxide, 1,4-dichlorobenzene Zero dipole moment needs a symmetric shape where bon... Electronegativity, Fajan's rule, dipole moment 1 answer
An element has a body centered cubic (bcc) structure with a cell edge of 288 pm. The atomic radius is : Answer: 1. sqrt3/4×288 pm In a bcc unit cell atoms touch along the body diagonal. Body diagonal =sqrt3 a=4r . r=sqrt3/4a=sqrt3/4×288\ pm≈124... Metallic bonding and hydrogen bonding 1 answer
Identify a molecule which does not exist. Answer: 1. He ₂ A molecule exists only if its bond order (from molecular orbital theory) is greater than zero. He₂ : 4 electrons, σ1s²σ^*1s²... Molecular orbital theory, bond order, bond length, bond energy 1 answer
Hydrolysis of sucrose is given by the following reaction.Sucrose + H_2O ⇌ Glucose + FructoseIf the equilibrium constant (K_c) is 2×10^13 at 300 K, the value of Δ_rG^ at the same temperature will be : Answer: 1. -8.314 J mol ⁻¹ K ⁻¹×300 K ×ln(2×10¹³) Standard Gibbs energy and equilibrium constant are related by Δ_rG^ominus=-RTln K . Substi... Gibbs energy change and equilibrium constant 1 answer
Identify the incorrect match.Name | IUPAC Official Name(a) Unnilunium | (i) Mendelevium(b) Unniltrium | (ii) Lawrencium(c) Unnilhexium | (iii) Seaborgium(d) Unununnium | (iv) Darmstadtium Answer: 4. (d), (iv) IUPAC temporary names come from the atomic number: un=1, nil=0, tri=3, hex=6. Unnilunium = 101 = Mendelevium. Match (a)... Modern periodic law and periodic table, s, p, d, f blocks 1 answer
Find out the solubility of Ni(OH)_2 in 0.1 M NaOH. Given that the ionic product of Ni(OH)_2 is 2×10^-15. Answer: 1. 2×10⁻¹³ M In 0.1 M NaOH the common ion OH^- is already present, so the OH^- from Ni(OH)₂ can be ignored. mathrmNi(OH)₂ ⇌ Ni²⁺ + 2... Solubility product 1 answer
Identify compound X in the following sequence of reactions :Toluene (C_6H_5CH_3) Cl_2/h X [373\ K]H_2O Benzaldehyde (C_6H_5CHO) Answer: 3. Benzal chloride (C ₆ H ₅ CHCl ₂ ) Free-radical chlorination of the side chain ( Cl₂/hν ) replaces methyl hydrogens. To get an ald... Preparation, properties and reactions 1 answer
Which of the following amine will give the carbylamine test ? Answer: 1. Aniline (C ₆ H ₅ NH ₂ ) The carbylamine test (heating with CHCl₃ and alcoholic KOH to give a foul-smelling isocyanide) is given o... Identification of 1/2/3 amines 1 answer
Reaction between acetone and methylmagnesium chloride followed by hydrolysis will give : Answer: 3. Tert. butyl alcohol Grignard reagents add to the carbonyl group. A ketone gives a tertiary alcohol after hydrolysis. mathrm(CH₃)₂... Aldehydes and ketones: HCN, NH3 derivatives, Grignard, oxidation, reduction (Wolff-Kishner, Clemmensen) 1 answer
Identify the correct statements from the following :(a) CO_2(g) is used as refrigerant for ice-cream and frozen food.(b) The structure of C_60 contains twelve six carbon rings and twenty five carbon rings.(c) ZSM-5, a type of zeolite, is used to conv… Answer: 4. (c) and (d) only Check each statement. (a) Solid CO₂ (dry ice) is the refrigerant for ice-cream and frozen food, not the gas. The... Electronic configuration and general trends, Group 13 and 14 1 answer

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