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3 questions

Name the chronic respiratory disorder caused mainly by cigarette smoking : Answer: 1. Emphysema Key idea: Cigarette smoking mainly causes emphysema. Smoke damages the alveolar walls, so the surface area for gas exch... Breathing and respiration: mechanism, exchange and transport of gases, volumes, disorders 1 answer
A system of rotating crops with legume or grass pasture to improve soil structure and fertility is called : Answer: 1. Ley farming Key idea: Ley farming alternates cereal crops with legume or grass pasture for a few years to restore soil structure... Biocontrol agents and biofertilizers 1 answer
Mitochondria and chloroplast are :(a) semi-autonomous organelles.(b) formed by division of pre - existing organelles and they contain DNA but lack protein synthesizing machinery.Which one of the following options is correct ? Answer: 3. (a) is true but (b) is false. Key idea: Mitochondria and chloroplasts are semi-autonomous organelles. (a) True. They have their o... Mitochondria, ribosomes, plastids, microbodies 1 answer
In context of Amniocentesis, which of the following statement is incorrect ? Answer: 4. It can be used for detection of Cleft palate. Key idea: Amniocentesis tests fluid-borne foetal cells for chromosomal and metaboli... Amniocentesis, infertility and ART (IVF, ZIFT, GIFT) 1 answer
In a chloroplast the highest number of protons are found in : Answer: 2. Lumen of thylakoids Key idea: During the light reactions, protons build up inside the thylakoid lumen. They come from water split... Light reactions, cyclic and non-cyclic photophosphorylation, chemiosmosis 1 answer
Natural rubber has : Answer: 1. All cis-configuration Key idea: natural rubber is cis-1,4-polyisoprene. All the double bonds in the chain have cis configuration,... Functional groups, homologous series, classification 1 answer
Which of the following is an analgesic ? Answer: 1. Novalgin Key idea: an analgesic relieves pain. Novalgin is an analgesic (and antipyretic). Penicillin, streptomycin and chloromyc... Functional groups, homologous series, classification 1 answer
Fog is a colloidal solution of : Answer: 1. Liquid in gas Key idea: fog consists of tiny water droplets (liquid) dispersed in air (gas), so it is a colloid of liquid in gas,... Lyophilic and lyophobic sols 1 answer
The product formed by the reaction of an aldehyde with a primary amine is : Answer: 1. Schiff base Key idea: an aldehyde (or ketone) condenses with a primary amine with loss of water to give an imine, R-CH=N-R' , als... Aldehydes and ketones: HCN, NH3 derivatives, Grignard, oxidation, reduction (Wolff-Kishner, Clemmensen) 1 answer
Match items of Column I with the items of Column II and assign the correct code :Column I: (a) Cyanide process; (b) Froth floatation process; (c) Electrolytic reduction; (d) Zone refiningColumn II: (i) Ultrapure Ge; (ii) Dressing of ZnS; (iii) Extrac… Answer: 1. (iv) (ii) (iii) (i) Key idea: match each process with its use. (a) Cyanide process: extraction of gold (Au), iv. (b) Froth floata... Transition elements: configuration, occurrence and characteristics 1 answer
Which one of the following statements is correct when SO_2 is passed through acidified K_2Cr_2O_7 solution ? Answer: 4. Green Cr₂(SO₄)₃ is formed. Key idea: SO₂ is a reducing agent and acidified dichromate is an oxidising agent. mathrmCr₂O₇²⁻+3SO₂+2... K2Cr2O7 and KMnO4 1 answer
The electronic configurations of Eu (Atomic No. 63), Gd (Atomic No. 64) and Tb (Atomic No. 65) are : Answer: 4. [Xe]4f⁷6s² , [Xe]4f⁷5d¹6s² and [Xe]4f⁹6s² Key idea: half-filled 4f⁷ is extra stable, and Gd and Tb follow from it. Eu (63): [Xe]4... Lanthanoids and lanthanoid contraction 1 answer
Two electrons occupying the same orbital are distinguished by : Answer: 4. Spin quantum number Key idea: two electrons in the same orbital have the same n, l and m. By the Pauli exclusion principle they m... Quantum numbers and shapes of s, p, d orbitals 1 answer
When copper is heated with conc. HNO_3 it produces : Answer: 1. Cu(NO₃)₂ and NO₂ Key idea: the reduction product of nitric acid depends on its concentration. Cu+4HNO₃(conc.)→ Cu(NO₃)₂+2NO₂+2H₂O... General trends, Group 15 and 16 1 answer
Which of the following reagents would distinguish cis-cyclopenta-1, 2-diol from the trans-isomer ? Answer: 1. Acetone Key idea: only the cis-1,2-diol has both -OH groups on the same side of the ring, so it can form a cyclic five-membered k... Alcohols: identification of 1/2/3 alcohols, dehydration mechanism 1 answer
The correct thermodynamic conditions for the spontaneous reaction at all temperatures is : Answer: 3. Δ H < 0 and Δ S > 0 Key idea: Δ G=Δ H-TΔ S . A reaction is spontaneous at all temperatures when Δ G<0 for every T. This needs Δ H... Second law, entropy and spontaneity 1 answer
Lithium has a bcc structure. Its density is 530\ kg\ m^-3 and its atomic mass is 6.94\ g\ mol^-1. Calculate the edge length of a unit cell of Lithium metal. (N_A = 6.02×10^23\ mol^-1) Answer: 2. 352 pm Key idea: ρ=Z M/N_A a³ , with Z = 2 for bcc. ρ=530\ mathrmkg m⁻³=0.530\ mathrmg cm⁻³ . a³=frac2×6.946.02×10²³×0.530=4.35×1... Atomic and molecular masses, mole concept, molar mass 1 answer
Which one of the following orders is correct for the bond dissociation enthalpy of halogen molecules ? Answer: 2. Cl₂ > Br₂ > F₂ > I₂ Key idea: bond dissociation enthalpy generally falls down group 17 (bigger atoms, longer bonds), but F₂ is un... General trends, Group 17 and 18 1 answer
Equal moles of hydrogen and oxygen gases are placed in a container with a pin-hole through which both can escape. What fraction of the oxygen escapes in the time required for one-half of the hydrogen to escape ? Answer: 1. 1/8 Key idea: Graham's law, rate of effusion ∝ 1/√(M) . fracr_(H_2)r_(O_2)=√(32/2)=4 Both gases start with equal moles and leave... Atomic and molecular masses, mole concept, molar mass 1 answer
Consider the nitration of benzene using mixed conc. H_2SO_4 and HNO_3. If a large amount of KHSO_4 is added to the mixture, the rate of nitration will be : Answer: 2. slower Key idea: nitration needs the nitronium ion, formed by HNO₃+2H₂SO₄⇌ NO₂^++H₃O^++2HSO₄^- KHSO₄ adds a large amount of HSO₄^... Electrophilic substitution: halogenation, nitration, Friedel-Crafts 1 answer
Predict the correct order among the following : Answer: 1. lone pair - lone pair > lone pair - bond pair > bond pair - bond pair Key idea (VSEPR): a lone pair is held only by one nucleus,... VSEPR theory and shapes of molecules 1 answer
The product obtained as a result of a reaction of nitrogen with CaC_2 is : Answer: 1. Ca(CN)₂ Key idea: calcium carbide absorbs nitrogen at high temperature to give calcium cyanamide (nitrolim) and carbon. CaC₂+N₂→... General trends, Group 15 and 16 1 answer
Consider the following liquid - vapour equilibrium.Liquid ⇌ VapourWhich of the following relations is correct ? Answer: 4. dln P/dT = Δ H_v/RT² Key idea: this is the Clausius-Clapeyron equation for liquid-vapour equilibrium: dln P/dT=Δ H_v/RT² Vapour p... Gibbs energy change and equilibrium constant 1 answer
Match the compounds given in column I with the hybridisation and shape given in column II and mark the correct option.Column I: (a) XeF_6; (b) XeO_3; (c) XeOF_4; (d) XeF_4Column II: (i) distorted octahedral; (ii) square planar; (iii) pyramidal; (iv)… Answer: 1. (i) (iii) (iv) (ii) Key idea: use VSEPR for each xenon compound. XeF₆ : sp³d³ , 6 bond pairs + 1 lone pair, distorted octahedral... Valence bond theory, hybridization (s, p, d), resonance 1 answer

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