Chemistry

20 chapters 515 solved questions 21 tests

Ask a question

The structures of beryllium chloride in solid state and vapour phase, are : Answer: 1. Chain and dimer, respectively Key idea: BeCl₂ is electron deficient and completes its octet by bridging. In the solid state it fo... VSEPR theory and shapes of molecules 1 answer
Match List - I with List - II.List - I : (a) PCl_5 (b) SF_6 (c) BrF_5 (d) BF_3List - II : (i) Square pyramidal (ii) Trigonal planar (iii) Octahedral (iv) Trigonal bipyramidalChoose the correct answer from the options given below. Answer: 1. (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii) Key idea: use VSEPR to find shapes. PCl₅ : 5 bond pairs, trigonal bipyramidal (iv) SF₆ : 6... VSEPR theory and shapes of molecules 1 answer
Statement I : Acid strength increases in the order given as HF << HCl << HBr << HI.Statement II : As the size of the elements F, Cl, Br, I increases down the group, the bond strength of HF, HCl, HBr and HI decreases and so the acid strength increases… Answer: 1. Both Statement I and Statement II are true. Key idea: acid strength of hydrogen halides depends on the H-X bond strength. Down th... Valence, oxidation states and chemical reactivity 1 answer
Ethylene diaminetetraacetate (EDTA) ion is : Answer: 1. Hexadentate ligand with four "O" and two "N" donor atoms Key idea: EDTA ⁴⁻ is a hexadentate ligand. It has two nitrogen donor ato... Werner's theory, ligands, coordination number, denticity, chelation 1 answer
Zr (Z=40) and Hf (Z=72) have similar atomic and ionic radii because of : Answer: 3. lanthanoid contraction Key idea: lanthanoid contraction. Between Zr (4d) and Hf (5d) come the 14 lanthanoids, whose poor shieldin... Lanthanoids and lanthanoid contraction 1 answer
The maximum temperature that can be achieved in blast furnace is : Answer: 2. upto 2200 K Key idea: this is a recall fact for iron extraction. In the blast furnace the temperature rises from about 500 K at t... Transition elements: configuration, occurrence and characteristics 1 answer
The pK_b of dimethylamine and pK_a of acetic acid are 3.27 and 4.77 respectively at T (K). The correct option for the pH of dimethylammonium acetate solution is : Answer: 3. 7.75 Key idea: for a salt of a weak acid and a weak base, pH=7+1/2(pK_a-pK_b) . pH=7+1/2(4.77-3.27)=7+0.75=7.75 . Common ion effect, hydrolysis of salts 1 answer
Dihedral angle of least stable conformer of ethane is : Answer: 4. 0^° Key idea: the eclipsed conformation of ethane has the highest torsional strain, so it is least stable. In the eclipsed form t... Alkanes: conformations, halogenation mechanism 1 answer
The correct sequence of bond enthalpy of 'C–X' bond is : Answer: 2. CH₃-F > CH₃-Cl > CH₃-Br > CH₃-I Key idea: bond enthalpy decreases as the halogen gets larger (longer, weaker C-X bond). Bond leng... Nature of C-X bond 1 answer
Identify the compound that will react with Hinsberg's reagent to give a solid which dissolves in alkali. Answer: 3. CH₃CH₂-ddotNH₂ Key idea: Hinsberg's reagent (benzenesulphonyl chloride) reacts with primary and secondary amines; the sulphonamid... Identification of 1/2/3 amines 1 answer
What is the IUPAC name of the organic compound formed in the following chemical reaction ?Acetone [(ii) H_2O, H^+](i) C_2H_5MgBr,\ dry Ether Product Answer: 4. 2-methyl butan-2-ol Key idea: a Grignard reagent adds to a ketone to give a tertiary alcohol. mathrm(CH₃)₂C=O+C₂H₅MgBr→(CH₃)₂C(C₂... Aldehydes and ketones: HCN, NH3 derivatives, Grignard, oxidation, reduction (Wolff-Kishner, Clemmensen) 1 answer
An organic compound contains 78% (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is : [Atomic wt. of C is 12, H is 1] Answer: 3. CH₃ Key idea: divide percentage by atomic mass, then take the simplest ratio. C: 78/12=6.5 ; H: 22/1=22 . Ratio H : C = 22/6.5≈3.... Empirical and molecular formula calculations 1 answer
The molar conductance of NaCl, HCl and CH_3COONa at infinite dilution are 126.45, 426.16 and 91.0 S cm^2 mol^-1 respectively. The molar conductance of CH_3COOH at infinite dilution is. Choose the right option for your answer. Answer: 2. 390.71 S cm ² mol ⁻¹ Key idea: Kohlrausch's law of independent migration of ions. Lambda^°(CH₃COOH)=Lambda^°(CH₃COONa)+Lambda^°(H... Kohlrausch's law and applications 1 answer
Which of the following reactions is the metal displacement reaction ? Choose the right option. Answer: 2. Cr₂O₃ + 2Al xrightarrowΔ Al₂O₃ + 2Cr Key idea: a metal displacement reaction is one where a more reactive metal displaces a less... Oxidation and reduction, oxidation number 1 answer
The following solutions were prepared by dissolving 10 g of glucose (C_6H_12O_6) in 250 ml of water (P_1), 10 g of urea (CH_4N_2O) in 250 ml of water (P_2) and 10 g of sucrose (C_12H_22O_11) in 250 ml of water (P_3). The right option for the decreasi… Answer: 1. P₂ > P₁ > P₃ Key idea: for equal mass in equal volume, osmotic pressure π=CRT is proportional to moles, i.e. inversely proportion... Colligative properties 1 answer
The correct structure of 2,6-Dimethyl-dec-4-ene is : Answer: 1. [skeletal structure - see figure] Key idea: build the chain from the name: 10 carbons (dec), a double bond between C-4 and C-5, a... Nomenclature (trivial and IUPAC) 1 answer
Choose the correct option for graphical representation of Boyle's law, which shows a graph of pressure vs. volume of a gas at different temperatures : Answer: 4. [graph option - see figure] Key idea: Boyle's law: PV=constant at fixed T, so P vs V is a rectangular hyperbola. A higher T gives... Electromagnetic radiation, photoelectric effect, hydrogen spectrum 1 answer
BF_3 is planar and electron deficient compound. Hybridization and number of electrons around the central atom, respectively are : Answer: 3. sp² and 6 Key idea: BF₃ has three bond pairs and no lone pair on boron. Three electron domains give sp² hybridisation and trigona... Valence bond theory, hybridization (s, p, d), resonance 1 answer
For a reaction A→B, enthalpy of reaction is -4.2 kJ mol^-1 and enthalpy of activation is 9.6 kJ mol^-1. The correct potential energy profile for the reaction is shown in option. Answer: 2. [graph option - see figure] Key idea: Δ H<0 means the product B lies below reactant A; activation enthalpy 9.6 kJ/mol means the p... Effect of temperature, Arrhenius equation, activation energy 1 answer
Which one among the following is the correct option for right relationship between C_P and C_V for one mole of ideal gas ? Answer: 2. C_P - C_V = R Key idea: for one mole of an ideal gas, C_P exceeds C_V by exactly R (Mayer's relation). At constant pressure, heat... Heat capacity and molar heat capacity 1 answer
The correct option for the number of body centred unit cells in all 14 types of Bravais lattice unit cells is : Answer: 4. 3 Key idea: count the body-centred (I) cells among the 14 Bravais lattices. Cubic: primitive, body-centred, face-centred (1 body-... System, surroundings, extensive/intensive properties, state functions, processes 1 answer
Which one of the following methods can be used to obtain highly pure metal which is liquid at room temperature ? Answer: 3. Distillation Key idea: the metal liquid at room temperature is mercury, which is volatile with a low boiling point (630 K). Disti... Transition elements: configuration, occurrence and characteristics 1 answer
The major product of the following chemical reaction is :(CH_3)_2CH-CH=CH_2 + HBr (C_6H_5CO)_2O_2 ? Answer: 1. (CH₃)₂CH-CH₂-CH₂-Br Key idea: with peroxide, HBr adds to alkenes by a free-radical path: anti-Markovnikov (Kharasch peroxide effe... Alkenes: geometrical isomerism, electrophilic addition, Markovnikov and peroxide effect 1 answer
The major product formed in dehydrohalogenation reaction of 2-Bromo pentane is Pent-2-ene. This product formation is based on ? Answer: 1. Saytzeff's Rule Key idea: in dehydrohalogenation, the more substituted (more stable) alkene is the major product. This is Saytzef... Alkenes: geometrical isomerism, electrophilic addition, Markovnikov and peroxide effect 1 answer

← Previous

Page 10 of 22