Recent questions in Chemistry

Write (a) Reaction involved in the preparation of a biodegradable polyester. (b) Monomer unit of synthetic rubber (neoprene) (c) One use of Nylon -6,6

asked Oct 20, 2016 by meena.p

1 answer

Describe a chemical test in each case to distinguish between the following pairs of compounds. (a) Aniline and N-ethyl aniline (b) N- methyl propane -2 amine and N-ethyl methyl ethanamine

asked Oct 20, 2016 by meena.p

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Justify the following (a)(i) Sleeping pills are recommended to patient suffering from sleepless but it is not adorable to take them without consulting the doctor . (ii) Why do we require artificial sweetening agents (b) Write the composition of Dettol

asked Oct 20, 2016 by meena.p

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(a) Give one reaction of D- glucose which cannot be explained by its open chain structure . (b)Give one example each for essential and non essential amino acids (c) Differentiate between keratin and insulin .

asked Oct 20, 2016 by meena.p

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Account for the following : (a) Chloro methane reacts with KCN to form ethanenitrile as main product and with $AgCN$ to form methyl isocyanide as chief product . (b) Chloroform should be stored in dark coloured bottles and these bottle should be completely filled .

asked Oct 19, 2016 by meena.p

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Sodium crystallizes in a bcc unit cell , calculate the appropriate number of unit cell in $9.2\;g$ of sodium (Atomic mass of Na=23 u)

asked Oct 19, 2016 by meena.p

1 answer

Write balanced chemical equation for the following reactions : (a) Thermal decomposition of ammonium dichromate. (b) Reaction of $Cl_2$ with cold and deleted NaOH (c) When phosphine is passed through mercuric chloride solution .

asked Oct 19, 2016 by meena.p

1 answer

Out line the principle of the method used for refining of (a)Nickel (b)Zirconium (c) Tin

asked Oct 19, 2016 by meena.p

1 answer

Give reasons for the following observation : (a) Colloids Stabilize due to Brownian movement . (b) Cornell's smoke precipitation is fixed at the mouth of chimney used in factories. (c) Colloidal gold is used for intramuscular injection .

asked Oct 19, 2016 by meena.p

1 answer

(a) Calculate the charge in coulombs required for oxidation for 2 moles of water to oxygen. [Given $IF= 96,500\;c\;mol^{-1}$] (b) Zinc / Silver oxide cell is used is hearing aids and electric watches . The following reaction occur. $Zn(S) \to Z_n^{2+} (aq)+2e^{-} E^0_{Zn^{2+}/Zn}=-0.76\;V \\ Ag_20+H_2O+2e^{-} \to 2Ag +2 OH - E^0_{Ag^{+}/Ag}=0.344\;V$ Calculate (i) Standard potential of the cell (ii) Standard Gibbs energy .

asked Oct 19, 2016 by meena.p

1 answer

What are antiseptics ?

asked Oct 18, 2016 by meena.p

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(i) Give names of the reagents to bring about the following transformations. (a) Ethanoic acid to ethanol(b) Propan -1-ol to propanal(c) Pent -3 -en-2-ol to Pent -3-en-2-one(d) Sodium benzonte to benzene(ii) Arrange the following in the increasing order (a) Methanal, propanal, butanone, ethanal , propanone (nucleophilic addition reaction ) (b) Formaldehyde , acetone , acetaldehyde (reactivity towards HCN)(c) Acetophenone , P- toludehyde, p-nitrobenzaldehyde, benzaldehyde (nucleophilic addition reaction )

asked Oct 18, 2016 by meena.p

1 answer

(A)(a) Compare non transition and transition elements on the basis of their (i) Variability of oxidation states (ii) stability of oxidation states. (b) Give chemical reactions for the following observations: (i) Potassium permanganate is a good oxidising agent in basic medium. (ii) Inter convertibility of chromate ion and dichromate ion in aqueous solution depends Upon pH of the solution. (iii) Potassium permanganate is thermally unstable at $513\;K$. (B) Why do the d - block elements exhibit a large number of oxidation states than f- block elements

asked Oct 18, 2016 by meena.p

1 answer

Account for the following : (i) Transition elements show highest oxidation state in their oxides thanfluorides. (ii) Cu has positive electrode potential in the first transition series. (iii) Ionisation enthalpy of lanthanides is higher than actinides. (iv) Potassium dichromate is a good oxidising agent in acidic medium. (v) Actinides show more number of oxidation states than lanthanides.

asked Oct 18, 2016 by meena.p

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How is the present of $SO_2$ detected ?

asked Oct 18, 2016 by meena.p

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How do antidepressant drugs counteract feeling of depression ?

asked Oct 17, 2016 by meena.p

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What is the function of sulphur in Vulcanization of rubber ?

asked Oct 17, 2016 by meena.p

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Give Reason The monoamino monocarboxylic acids have two PH values

asked Oct 17, 2016 by meena.p

1 answer

How can you separate a mixture of primary , secondary and tertiary amines ? Write chemical reactions involved in the process .

asked Oct 17, 2016 by meena.p

1 answer

Predict the product of the following reaction :

asked Oct 17, 2016 by meena.p

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The carbon - oxygen bond in phenol is slightly stronger than that in methanol . Why ?

asked Oct 17, 2016 by meena.p

1 answer

Why do the d - block elements exhibit a large number of oxidation states than f- block elements

asked Oct 17, 2016 by meena.p

1 answer

Copper can be extracted by hydro metallurgy but not zinc. Explain .

asked Oct 17, 2016 by meena.p

1 answer

What is the difference between physisorption and chemisorption?

asked Oct 17, 2016 by meena.p

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Resistance of a conductivity cell filled with $0.1 \;mol^{-1}KCl$ solution is $100 \Omega$ . If the resistance of the same cell when filled with $0.2\;mol L^{-1}\;KCl$ solution is $520\; \Omega$ . Calculate the conductivity of $0.2 mol L^{-1} \;KCl$ solution . The conductivity of $0.1\;mol L^{-1} KCl$ solution is $1.29\;s.m$

asked Oct 14, 2016 by meena.p

1 answer

Alcohols act as weak bases . explain

asked Oct 14, 2016 by meena.p

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a)Give the mechanism of preparation of ethoxy ethane from ethanol b) Alcohols act as weak bases . explain .

asked Oct 13, 2016 by meena.p

1 answer

Complete the following reactions: $(i) X_eF_6 +H_2O \to$ _+ ___ $\\ (ii) X_eF_6 +H_2O \to$ _ + ___ $ \\ (iii) Cl_2+H_2O \to$ _ + ___

asked Oct 13, 2016 by meena.p

1 answer

Absorption of gases on solid surface is generally exothermic because absorption

asked Oct 13, 2016 by meena.p

1 answer

Why Nitrogen is a gas whereas phosphorous is a solid ?

asked Oct 13, 2016 by meena.p

0 answers

Resonance is due to :

asked Dec 22, 2015 by meena.p

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The property of catenation is strongestin carbon because :

asked Dec 22, 2015 by meena.p

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Polythene is a/an:

asked Dec 22, 2015 by meena.p

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Gold and silver are extracted from their respective ares by

asked Dec 22, 2015 by meena.p

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Heating of carbonates to remove carbon dioxide is called

asked Dec 22, 2015 by meena.p

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Which oil is used as frother in the frith floatation process ?

asked Dec 22, 2015 by meena.p

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Cinnabar is the are containing

asked Dec 22, 2015 by meena.p

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Which metal is obtained by self reduction process ? or Where the proportionally constant k is called rate constant

asked Dec 22, 2015 by meena.p

1 answer

Specific gravity of slag is

asked Dec 22, 2015 by meena.p

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Van Arkel method of purification of metals involves converting the metal to a

asked Dec 22, 2015 by meena.p

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Which of the following substance contains both ca and Mg ?

asked Dec 22, 2015 by meena.p

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Which of the following fluxes is used to removed acidic impurites in metallurgical process ?

asked Dec 22, 2015 by meena.p

1 answer

Malachite is a mineral of

asked Dec 22, 2015 by meena.p

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Mercury is transported in metal containers made up of

asked Dec 22, 2015 by meena.p

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Mercury is transported in metal containers made up of

asked Dec 22, 2015 by meena.p

1 answer

Zinc blende is

asked Dec 22, 2015 by meena.p

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In the extraction of iron slag produced is

asked Dec 22, 2015 by meena.p

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Chromium is obtained by reducing purified chromite ore with

asked Dec 22, 2015 by meena.p

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Refractory material are used in furnaces because they

asked Dec 22, 2015 by meena.p

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Cyanide process is used for obtaining

asked Dec 22, 2015 by meena.p

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