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3 questions

Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations :a. 60 mL M/10 HCl + 40 mL M/10 NaOHb. 55 mL M/10 HCl + 45 mL M/10 NaOHc. 75 mL M/5 HCl + 25 mL M/5 NaOHd. 100 mL M/10 HCl + 100 mL M/10 NaOHpH… Answer: 4. c pH = 1 means [H^+]=0.1 M, so excess strong acid of that concentration must remain after mixing. a: HCl 6 mmol, NaOH 4 mmol, exc... Ionization constants, ionization of water, pH scale 1 answer
The solubility of BaSO_4 in water is 2.42×10^-3 gL^-1 at 298 K. The value of its solubility product (K_sp) will be(Given molar mass of BaSO_4 = 233 g mol^-1) Answer: 1. 1.08×10⁻¹⁰ mol ² L ⁻² Convert solubility to mol/L, then use K_sp=s² for a 1:1 salt. s=dfrac2.42×10⁻³233=1.04×10⁻⁵\ mathrmmol L⁻¹... Solubility product 1 answer
On which of the following properties does the coagulating power of an ion depend ? Answer: 2. Both magnitude and sign of the charge on the ion According to the Hardy-Schulze rule, the ion that coagulates a colloid is the on... Lyophilic and lyophobic sols 1 answer
Considering Ellingham diagram, which of the following metals can be used to reduce alumina ? Answer: 2. Mg In an Ellingham diagram, a metal can reduce an oxide only if its own oxide-formation line lies below that of the oxide to be r... Gibbs energy change and equilibrium constant 1 answer
The correct order of atomic radii in group 13 elements is Answer: 4. B < Ga < Al < In < Tl Atomic radius generally increases down a group, but Ga is smaller than Al. Gallium follows the d-block (3d)... Atomic and ionic radii 1 answer
In the structure of ClF_3, the number of lone pairs of electrons on central atom 'Cl' is Answer: 3. two Count electron pairs on Cl in ClF₃ : Cl has 7 valence electrons, 3 are used for bonds with F, leaving 4 electrons = 2 lone pa... VSEPR theory and shapes of molecules 1 answer
The correct order of N-compounds in its decreasing order of oxidation states is Answer: 1. HNO ₃ , NO, N ₂ , NH ₄ Cl Find the oxidation state of N in each compound. HNO₃ : +5 NO: +2 N₂ : 0 NH₄Cl : -3 The decreasing order... Oxidation and reduction, oxidation number 1 answer
Which of the following statements is not true for halogens ? Answer: 2. All but fluorine show positive oxidation states. We need the statement that is NOT true for halogens. Option 1: Cl, Br, I and (as... General trends, Group 17 and 18 1 answer
Which one of the following elements is unable to form MF_6^3- ion ? Answer: 2. B mathrmMF₆³⁻ needs six F^- around M, so M must use d orbitals to exceed an octet. Boron is in period 2 and has no d orbitals; it... Electronic configuration and general trends, Group 13 and 14 1 answer
Regarding cross-linked or network polymers, which of the following statements is incorrect ? Answer: 4. They contain strong covalent bonds in their polymer chains. Cross-linked (network) polymers are formed from bi- and tri-functiona... Amino acids, peptide bond, protein structure, denaturation 1 answer
Nitration of aniline in strong acidic medium also gives m-nitroaniline because Answer: 4. In acidic (strong) medium aniline is present as anilinium ion. Aniline is nitrated with a mixture of HNO₃ and H₂SO₄ , which is st... Directive influence in monosubstituted benzene 1 answer
The difference between amylose and amylopectin is Answer: 1. Amylopectin have 1 → 4 α -linkage and 1 → 6 α -linkage Both amylose and amylopectin are polymers of α -D-glucose, and they differ... Carbohydrates: classification, glucose, fructose 1 answer
A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. H_2SO_4. The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP will be Answer: 2. 2.8 Conc. H₂SO₄ dehydrates both acids. KOH absorbs CO₂ , so only CO remains. HCOOH→ CO+H₂O : 2.3 g / 46 = 0.05 mol, gives 0.05 mo... Carboxylic acids: acidic strength 1 answer
In the reaction[phenol + CHCl_3 + NaOH → sodium salicylaldehyde (o-O^-Na^+ C_6H_4 CHO), shown as a structure]the electrophile involved is Answer: 4. dichlorocarbene (:CCl ₂ ) This is the Reimer-Tiemann reaction. The electrophile is dichlorocarbene. The base removes a proton fro... Phenols: acidity, electrophilic substitution, Reimer-Tiemann 1 answer
Carboxylic acids have higher boiling points than aldehydes, ketones and even alcohols of comparable molecular mass. It is due to their Answer: 4. formation of intermolecular H-bonding Carboxylic acids form strong intermolecular hydrogen-bonded dimers, so more energy is neede... Carboxylic acids: acidic strength 1 answer
Compound A, C_8H_10O, is found to react with NaOI (produced by reacting Y with NaOH) and yields a yellow precipitate with characteristic smell.A and Y are respectively Answer: 2. 1-phenylethanol (C ₆ H ₅ -CH(OH)-CH ₃ ) and I ₂ A positive iodoform test (yellow precipitate with characteristic smell) needs a C... Alpha-hydrogen acidity, aldol, Cannizzaro, haloform 1 answer
Which of the following molecules represents the order of hybridisation sp^2, sp^2, sp, sp from left to right atoms ? Answer: 3. CH ₂ =CH - C equiv CH A carbon in a double bond is sp² , one in a triple bond is sp . mathrmCH₂=CH-CequivCH has carbons sp²,sp²,s... Tetravalency of carbon, hybridization and shapes 1 answer
In the circuit shown in the figure, the input voltage V_i is 20 V, V_BE = 0 and V_CE = 0. The values of I_B, I_C and β are given by Answer: 4. I_B = 40 μ A, I_C = 5 mA, β = 125 From the figure: R_B=500\ kΩ , R_C=4\ kΩ , supply 20 V, V_i=20 V, with V_BE=0 and V_CE=0 . I_B=... Semiconductors 1 answer
In the combination of the following gates the output Y can be written in terms of inputs A and B as Answer: 3. A·B+A· B Read the figure: the upper AND gate gets A and overline B ; the lower AND gate gets overline A and B . An OR gate joins... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
In a p-n junction diode, change in temperature due to heating Answer: 4. affects the overall V - I characteristics of p-n junction Heating changes the number of thermally generated electron-hole pairs,... p-n junction diode I-V characteristics 1 answer
Unpolarised light is incident from air on a plane surface of a material of refractive index 'μ'. At a particular angle of incidence 'i', it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options… Answer: 3. Reflected light is polarised with its electric vector perpendicular to the plane of incidence When reflected and refracted rays a... Polarization, Brewster's law, Polaroids 1 answer
In Young's double slit experiment the separation d between the slits is 2 mm, the wavelength λ of the light used is 5896 Å and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20^°. To increase… Answer: 3. 1.9 mm Angular fringe width is θ=λ/d , so θ∝1/d for fixed λ . d₂/d₁=θ₁/θ₂⇒ d₂=2×0.20/0.21≈1.9\ mm The slit separation must be dec... Interference and Young's double-slit experiment 1 answer
An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of Answer: 2. large focal length and large diameter Angular magnification of an astronomical telescope is m=f_o/f_e , so a large objective foca... Microscope and astronomical telescope 1 answer
An electron of mass m with an initial velocity V=V_0 i (V_0>0) enters an electric field E=-E_0 i (E_0 = constant >0) at t = 0. If λ_0 is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is Answer: 1. λ₀/(1+eE₀/mV₀t) The electron has charge -e and the field is -E₀hat i , so the force is +eE₀hat i . It accelerates along its motio... Matter waves, de Broglie relation 1 answer

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