Recent questions and answers in 2015

In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with -

answered Mar 23, 2020 by meena.clay6

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Which is the correct order of increasing energy of the listed orbitals in the atom of titanium ? (At. no Z = 22)

answered Mar 23, 2020 by meena.clay6

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Which of the following reaction(s) can be used for the preparation of alkyl halides ? (I) $CH_3CH_2OH + HCl \xrightarrow{anh. ZnCl_2}$ (II) $CH_3CH_2OH + HCl \to$ (III) $(CH_3)_3COH + HCl \to$ (IV) $(CH_3)_2 CHOH + HCl \xrightarrow{anh. ZnCl_2}$

answered Mar 23, 2020 by meena.clay6

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Method by which Aniline cannot be prepared is -

answered Mar 23, 2020 by meena.clay6

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answered Mar 23, 2020 by meena.clay6

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The oxidation of benzene by $V_2O_5$ in the presence of air produces -

answered Mar 23, 2020 by meena.clay6

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What is the mass of the precipitate formed when 50 mL of 16.9% solution of $AgNO_3$ is mixed with 50 mL of 5.8% NaCl solution ? (Ag = 107.3, N = 14, O = 16, Na = 23, Cl = 35.5)

answered Mar 23, 2020 by meena.clay6

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The variation of the boiling points of the hydrogen halides is in the order HF > HI > HBr > HCl. What explains the higher boiling point of hydrogen fluoride ?

answered Mar 23, 2020 by meena.clay6

2 answers

Number of possible isomers for the complex $[Co(en)_2Cl_2]Cl$ will be : (en = ethylene diamine)

answered Mar 23, 2020 by meena.clay6

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What is the pH of the resulting solution when equal volumes of 0.1 M NaOH and 0.01 M HCl are mixed ?

answered Mar 23, 2020 by meena.clay6

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In an $S_N1$ reaction on chiral centres, there is -

answered Mar 23, 2020 by meena.clay6

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Which one of the following esters gets hydrolysed most easily under alkaline conditions -

answered Mar 23, 2020 by meena.clay6

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Reaction of a carbonyl compound with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is -

answered Mar 23, 2020 by meena.clay6

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The sum of coordination number and oxidation number of the metal M in the complex $[M(en)_2(C_2O_4)]Cl$ (where en is ethylenediamine) is -

answered Mar 23, 2020 by meena.clay6

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The following reaction is known by the name -

answered Mar 23, 2020 by meena.clay6

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Two possible stero-structuers of $CH_3CHOH.COOH$ , which are optically active, are called :

answered Mar 23, 2020 by meena.clay6

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The stability of +1 oxidation state among Al, Ga, In and Tl in creases in the sequence -

answered Mar 23, 2020 by meena.clay6

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The correct statement regarding defects in crystalline solids is

answered Mar 23, 2020 by meena.clay6

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20.0 g of magnesium carbonate sample decomposes on hating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample ?

answered Mar 23, 2020 by meena.clay6

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The heat of combustion of carbon to $CO_2$ is $–393.5\; kJ/mol$ . The heat released upon formation of $35.2 \;g$ of $CO_2$ from carbon and oxygen gas is -

answered Mar 23, 2020 by meena.clay6

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Hybridization involved in complex the $[Ni(CN)_4]^{2–}$ is : (At. No. Ni = 28)

answered Mar 23, 2020 by meena.clay6

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A gas such as carbon monoxide would be most likely to obey the ideal gas law at :

answered Mar 23, 2020 by meena.clay6

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Which of the following statements is not correct for a nucleophile?

answered Mar 23, 2020 by meena.clay6

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If Avogadro number NA, is changed from $6.022 \times 10^{23} mol^{–1}$ to $6.022 \times 10^{20} \;mol^{–1}$ , this would change :

answered Mar 23, 2020 by meena.clay6

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The name of complex ion, $[Fe(CN)_6]^{3–}$ is :

answered Mar 19, 2020 by meena.clay6

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The vacant space in bcc lattice unit cell is :

answered Mar 19, 2020 by meena.clay6

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Reaction of phenol with chloroform in presence of dilute sodium hydroxide finally introduces which one of the following functional group ?

answered Mar 19, 2020 by meena.clay6

1 answer

Assuming complete ionization, same moles of which of the following compounds will require the least amount of acidified $KMnO_4$ for complete oxidation?

answered Mar 19, 2020 by meena.clay6

2 answers

In the reaction with HCl, an alkene reacts in accordance with the Markovnikov's rule, to give a product 1-chloro-1- methylcyclohexane. The possible alkene is :

answered Mar 19, 2020 by meena.clay6

1 answer

In which of the following pairs, both the species are not isostructural ?

answered Mar 19, 2020 by meena.clay6

1 answer

The number of water molecules is maximum in :

answered Mar 19, 2020 by meena.clay6

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Decreasing order of stability of $O_2, O_2^-, O_2^+$ and $O_2^{2-}$ is :

answered Mar 19, 2020 by meena.clay6

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Strong reducing behaviour of $H_3PO_2$ is due to :

answered Mar 19, 2020 by meena.clay6

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On heating which of the following releases $CO_2$ most easily ?

answered Mar 19, 2020 by meena.clay6

1 answer

Caprolactam is used for the manufacuture of :

answered Mar 19, 2020 by meena.clay6

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Aqueous solution of which of the following compounds is the best conductor of electric current ?

answered Mar 19, 2020 by meena.clay6

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Which one of the following pairs of solution is not an acidic buffer ?

answered Mar 19, 2020 by meena.clay6

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If the equilibrium constant for $N_2 (g) + O_2(g) \leftrightharpoons 2NO (g)$ is $K$ , the equilibrium constant for $\frac{1}{2} N_2(g) + \frac{1}{2}O_2 (g) \leftrightharpoons NO (g)$ will be :

answered Mar 18, 2020 by meena.clay6

1 answer

The number of structural isomers possible from the molecular formula $C_3H_9N$ is

answered Mar 18, 2020 by meena.clay6

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The formation of the oxide ion, $O^{2–}$ (g), from oxygen atom requires first an exothermic and then an endothermic step as shown below : $O(g) + e^- \to O^- (g), \Delta_f H^{\ominus} = -141 kJ\;mol^{-1}$ $O^-(g) + e^- \to O^{2-} (g), \Delta_f H^{\ominus} = +780 kJ\;mol^{-1}$ Thus process of formation of $O^{2–}$ in gas phase is unfavourable even though $O^{2–}$ is isoelectronic with neon. It is due to the fact that :

answered Mar 18, 2020 by meena.clay6

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Gadolinium belongs to 4f series. It's atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?

answered Mar 18, 2020 by meena.clay6

1 answer

2,3-Dimethyl-2-butene can be prepared by heating which of the following compounds with a strong acid?

answered Mar 18, 2020 by meena.clay6

1 answer

A beam of light consisting of red, green and blue colors is incident on a right angled prism. The refractive index of the material of the prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47, respectively. The prism will :

answered Feb 10, 2020 by priyanka.clay6

1 answer

A photoelectric surface is illuminated successively by monochromatic light of wavelength $\lambda$ and $\frac{\lambda}{2}$ . If the maximum kinetic energy of the emitted photoelectrons in the seconds case is 3 times that in the first case, the work function of the surface of the material is : (h = Planck’s constant, c = speed of light)

answered Feb 10, 2020 by priyanka.clay6

1 answer

The value of coefficient of volume expansion of glycerin is $5 \times 10^{–4} K^{–1}$ . The fractional change in the density of glycerin for a rise of $40^°C$ in its temperature, is :

answered Feb 10, 2020 by priyanka.clay6

1 answer

In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of the image is I. The magnification of the telescope is :

answered Feb 10, 2020 by priyanka.clay6

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Water rises to a height ‘h’ in capillary tube. If the length of capillary tube above the surface of water is made less than ‘h’, then :

answered Feb 10, 2020 by priyanka.clay6

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A circuit contains an ammeter, a battery of 30 V and a resistance 40.8 ohm all connected in series. If the ammeter has a coil of resistance 480 ohm and a shunt of 20 ohm, the reading in the ammeter will be :

answered Feb 10, 2020 by priyanka.clay6

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If dimensions of critical velocity $v_c$ of a liquid flowing through a tube are expressed as $[η^x ρ^y r^z]$ , where $η, ρ$ and $r$ are the coefficient of viscosity of liquid, density of liquid and radius of the tube respectively, then the values of $x, y,$ and $z$ are given by :

answered Feb 10, 2020 by priyanka.clay6

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The input signal given to a CE amplifier having a voltage gain of 150 is $V_i = 2 \cos ( 15t + \frac{\pi}{3})$ . The corresponding output signal will be :

answered Feb 10, 2020 by priyanka.clay6

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