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Recent questions tagged chemistry
Questions
Draw the structure of $BrF_3$ molecule
cbse
class12
chemistry
sec-c
ch-9
p-block-elements
asked
Oct 24, 2016
by
meena.p
1
answer
The second and third rows of transition elements resemble each other much more than they resemble the first row. explain why ?
cbse
class12
chemistry
sec-c
ch-8
d-and-f-block-elements
asked
Oct 24, 2016
by
meena.p
1
answer
write the disproportionate reaction of that oxoacids of nitrogen in which nitrogen is in +3 oxidation state .
cbse
class12
chemistry
sec-c
ch-10
haloalkanes-and-haloarenes
asked
Oct 24, 2016
by
meena.p
1
answer
What type of colloidal sols are formed in the following : (i) Sulphur vapours are passed through colled water (ii) White of an egg is mixed with water . (iii) Soap solution
cbse
class12
chemistry
sec-c
ch-4
chemical-kinetics
asked
Oct 24, 2016
by
meena.p
1
answer
(a) Give names of the reagents to bring about the following transformations : (i) Ethanoic acid to ethanol (ii) Propan -1-ol to propanal (iii) Pent -3-en-2-ol pent-3-en-2-one (iv) Sodium benzoate to benzene (b) Arrange in the following in increasing order of : (i) Methanal , Propanal, Butanone, ethanal,Propanone(Nucleophilic addition reaction ) (ii) Formaldehyde , Acetone , Acetaldehyde (reactivity towards HCN) (iii) Acetophenone, p- tolualdehyde, p-nitrobenzaldehyde, Benzaldehyde(nucleophilic addition reaction ).
cbse
class12
chemistry
sec-e
ch-11
alcohols-phenols-and-ethers
asked
Oct 24, 2016
by
meena.p
1
answer
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
cbse
class12
chemistry
sec-e
ch-8
d-and-f-block-elements
asked
Oct 24, 2016
by
meena.p
1
answer
(i)What is the freezing point of $0.4 $ molal solution of acetic acid in benzene in which it dimerises to the extent of $85\%$ Freezing point of benzene is $278.4 \;k$ and its molar heat of fusion is $10.042\;kj\; mol^{-1}$ (ii) 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 .
cbse
class12
chemistry
sec-e
ch-4
chemical-kinetics
asked
Oct 24, 2016
by
meena.p
1
answer
The resistance of the conductivity cell containing $0.001\;M\;KCl$ solution at $298\;K$ is $1500\Omega$. What is the cell constant if conductivity of $0.001\;M\;KCl$ solution at $298\;K$ is $0.14 \times 10^{-3} 5\;cm^{-1}? $
cbse
class12
chemistry
sec-c
ch-3
electrochemistry
asked
Oct 21, 2016
by
meena.p
1
answer
Differentiate between morality and molality of a solution . Explain how molality value of a solution can be converted into its molality
cbse
class12
chemistry
sec-c
ch-2
solutions
asked
Oct 21, 2016
by
meena.p
1
answer
(a)What changes occurs in the nature of egg protein on boiling ? (b) Name the type of bonding . Which stabilizes $\alpha - helix$ structure in proteins .
cbse
class12
chemistry
sec-b
ch-16
chemistry-in-everyday-life
asked
Oct 21, 2016
by
meena.p
1
answer
Out of $H_2O$ and $H_2S$ which one has higher, bond angle ?
cbse
class12
chemistry
sec-b
ch-9
p
-
block
p-block-elements
asked
Oct 21, 2016
by
meena.p
1
answer
Explain the role of (a) Cryolite in the electrolytic reduction of alumina . (b) carbon monoxide in the purification of nickel
cbse
class12
chemistry
sec-b
ch-3
electrochemistry
asked
Oct 21, 2016
by
meena.p
1
answer
Why does a solution of ethanol and cyclohexane show positive deviation from Raoult's law?
cbse
class12
chemistry
sec-b
ch-2
solutions
asked
Oct 21, 2016
by
meena.p
1
answer
A compound is formed by two elements, M and N . The element N forms CCP and atoms of M occupy $\large\frac{1}{3}$ rd of tetrahedral voids . What is the formula of the compound?
cbse
class12
chemistry
sec-b
ch-1
states-of-matter-solid-state
asked
Oct 21, 2016
by
meena.p
1
answer
a)How would you explain the amphoteric behavior of amino acids b) How does vulcanization change the properties of natural rubber ? (b)Explain what is meant by : (i) a peptide linkage (ii) a glycosidic linkage ?
cbse
class12
chemistry
sec-c
ch-14
biomolecules
asked
Oct 21, 2016
by
meena.p
1
answer
How will you prepare benzyl alcohol from benzaldehyde with out using a reducing agent ?
cbse
class12
chemistry
sec-a
ch-11
alcohols-phenols-and-ethers
asked
Oct 21, 2016
by
meena.p
1
answer
Arrange the following in order of decreasing acid strength $CH_3OH, H_2O ,C_6H_5OH$
cbse
class12
chemistry
sec-a
ch-11
alcohols-phenols-and-ethers
asked
Oct 21, 2016
by
meena.p
1
answer
Write the IUPAC name of $(i) [Fe(CN)_6]^{3-} \\ (ii) [CoCl_2(en)_2]Cl$
cbse
class12
chemistry
sec-a
ch-9
coordinate-compounds
asked
Oct 21, 2016
by
meena.p
1
answer
Why does physiorption decrease with increase of temperature ?
cbse
class12
chemistry
sec-a
ch-5
surface-chemistry
asked
Oct 20, 2016
by
meena.p
1
answer
Name one substance which can act as both (i) Analgesic and Antipyretic (ii) Antiseptic and disinfectant
cbse
class12
chemistry
sec-c
ch-14
biomolecules
asked
Oct 20, 2016
by
meena.p
1
answer
On dissolving $19.5\;g$ of $CH_2FOOH$ in $500\;g$ of water, a depression of $1^{\circ}C$ in freezing point of water is observed . Calculate the van't Hoff factor and dissociation constant of fluoro acetic acid Given $K_f= 1.86\;k kg mol^{-1}$
cbse
class12
chemistry
sec-c
ch-5
surface-chemistry
asked
Oct 20, 2016
by
meena.p
1
answer
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
cbse
class12
chemistry
sec-c
ch-15
polymers
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
cbse
class12
chemistry
sec-c
ch-9
coordinate-compounds
asked
Oct 20, 2016
by
meena.p
1
answer
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
cbse
class12
chemistry
sec-c
ch-14
biomolecules
asked
Oct 20, 2016
by
meena.p
1
answer
(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 .
cbse
class12
chemistry
sec-c
ch-7
p-block-elements
asked
Oct 20, 2016
by
meena.p
1
answer
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 .
cbse
class12
chemistry
sec-c
ch-6
isolation-of-elements
asked
Oct 19, 2016
by
meena.p
1
answer
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)
cbse
class12
chemistry
sec-b
ch-1
states-of-matter-solid-state
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 .
cbse
class12
chemistry
sec-c
ch-4
chemical-kinetics
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
cbse
class12
chemistry
sec-c
ch-3
electrochemistry
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 .
cbse
class12
chemistry
sec-c
ch-2
solutions
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 .
cbse
class12
chemistry
sec-c
ch-1
states-of-matter-solid-state
asked
Oct 19, 2016
by
meena.p
1
answer
What are antiseptics ?
cbse
class12
chemistry
sec-b
ch-16
chemistry-in-everyday-life
asked
Oct 18, 2016
by
meena.p
1
answer
(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 )
cbse
class12
chemistry
sec-c
ch-12
aldehydes-ketones-and-carboxylic-acids
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
cbse
class12
chemistry
sec-e
ch-8
d-and-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.
cbse
class12
chemistry
sec-e
ch-4
chemical-kinetics
asked
Oct 18, 2016
by
meena.p
1
answer
How is the present of $SO_2$ detected ?
cbse
class12
chemistry
sec-b
ch-2
solutions
asked
Oct 18, 2016
by
meena.p
1
answer
How do antidepressant drugs counteract feeling of depression ?
cbse
class12
chemistry
ch-16
sec-b
chemistry-in-everyday-life
asked
Oct 17, 2016
by
meena.p
1
answer
What is the function of sulphur in Vulcanization of rubber ?
cbse
class12
chemistry
ch-15
sec-c
polymers
asked
Oct 17, 2016
by
meena.p
1
answer
Give Reason The monoamino monocarboxylic acids have two PH values
cbse
class12
chemistry
ch-6
sec-c
isolation-of-elements
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 .
cbse
class12
chemistry
ch-9
sec-c
organic-compounds
asked
Oct 17, 2016
by
meena.p
1
answer
Predict the product of the following reaction :
cbse
class12
chemistry
ch-12
sec-c
aldehydes-ketones-and-carboxylic-acids
asked
Oct 17, 2016
by
meena.p
1
answer
The carbon - oxygen bond in phenol is slightly stronger than that in methanol . Why ?
cbse
class12
chemistry
ch-10
sec-c
haloalkanes-and-haloarenes
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
cbse
class12
chemistry
ch-8
sec-c
d-and-f-block-elements
asked
Oct 17, 2016
by
meena.p
1
answer
Copper can be extracted by hydro metallurgy but not zinc. Explain .
cbse
class12
chemistry
ch-5
sec-c
isolation
of
elements
asked
Oct 17, 2016
by
meena.p
1
answer
What is the difference between physisorption and chemisorption?
cbse
class12
chemistry
ch-3
sec-c
surface-chemistry
asked
Oct 17, 2016
by
meena.p
1
answer
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 $1.29\;s.m$
cbse
class12
chemistry
ch-3
sec-c
electrochemistry
asked
Oct 14, 2016
by
meena.p
1
answer
Alcohols act as weak bases . explain
cbse
class12
chemistry
ch-10
sec-c
alcohols-phenols-and-ethers
asked
Oct 14, 2016
by
meena.p
1
answer
a)Give the mechanism of preparation of ethoxy ethane from ethanol b) Alcohols act as weak bases . explain .
cbse
class12
chemistry
ch-10
sec-e
alcohols-phenols-and-ethers
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$ _______ + _________
cbse
class12
chemistry
ch-7
sec-c
p-block-elements
asked
Oct 13, 2016
by
meena.p
1
answer
Absorption of gases on solid surface is generally exothermic because absorption
cbse
class12
chemistry
ch-5
sec-a
surface-chemistry
asked
Oct 13, 2016
by
meena.p
1
answer
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