JEE-Main - Grade 12 - Chemistry - Surface Chemistry - Study ref# 9776
On the basis of data given below predict
which of the following gases shows least adsorption on a definite amount of
charcoal?
read moreJEE-Main - Grade 12 - Chemistry - General Principles and Processes of isolation of elements - Study ref# 9808Although carbon and hydrogen are better
reducing agents but they are not used to reduce metallic oxides at high
temperatures. Why? Answer: Because at high temperatures, carbon and
hydrogen react with metals to form carbides and hydrides resp... read moreJEE-Main - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9814On addition of conc.to a chloride salt,
colourless fumes are evolved but in case of iodide salt, violet fumes come
out. This is because
(a) reduces to HI to I2
(b) HI of violet colou... read moreJEE-Main - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9817Affinity for hydrogen decreases in the
group from fluorine to iodine. Which of the halogen acids should have highest
bond dissociation enthalpy?
(a) HF
(b) HCI
(c) HBr
(d) HI Answer: read moreJEE-Main - Grade 12 - Chemistry - The d and f block Elements - Study ref# 9856Why does copper not replace hydrogen from
acids? Answer: Copper not replace hydrogen from acids
because Cu has positive E̊ value, i.e., less reactive than
hydrogen which has electrode potential 0.00V.... read moreJEE-Main - Grade 12 - Chemistry - The d and f block Elements - Study ref# 9866Match the catalysts given in Column I
with the process given in Column II.
Column I
... read moreJEE-Main - Grade 12 - Chemistry - Haloalkanes and Haloarenes - Study ref# 9906Toluene reacts with a halogen in the
presence of iron (III) chloride giving ortho and para halo compounds. the
reaction is
(a) &nbs... read more JEE-Main - Grade 12 - Chemistry - Haloalkanes and Haloarenes - Study ref# 9907Which of the following is halogen
exchange reaction?
Answer: (a)Halogen exchange reactions are those
reactions in which one halide replaces another. In option (a) halogen (-X) is
replaced by iodine. This reaction is named as Finkelstein ... read moreJEE-Main - Grade 12 - Chemistry - Haloalkanes and Haloarenes - Study ref# 9908Which reagent will you use for the
following reaction?
(a) &... read more JEE-Main - Grade 12 - Chemistry - Haloalkanes and Haloarenes - Study ref# 9910In which of the following molecules
carbon atom marked with asterisk (*) is asymmetric?
(a) &... read more JEE-Main - Grade 12 - Chemistry - Haloalkanes and Haloarenes - Study ref# 9912The position of Br in the compound in can be
classified as……… .
(a) &... read more JEE-Main - Grade 12 - Chemistry - Haloalkanes and Haloarenes - Study ref# 9926Aryl chlorides and bromides can be easily
prepared by electrophilic substitution of arenes with chlorine and bromine
respectively in the presence of Lewis acid catalysts. But why does
preparation of aryl iodides requires presence of an oxidi... read moreJEE-Main - Grade 12 - Chemistry - Haloalkanes and Haloarenes - Study ref# 9928Classify the following compounds s
primary, secondary and tertiary halides.
a)
1-bromobut -2-ene
b)
4-bromopent -2-ene
c)
2-bromo-2-methylp... read moreJEE-Main - Grade 12 - Chemistry - Alcohols, Phenols and Ethers - Study ref# 9938CH3CH2OH can be
converted into CH3CHO by……… .
a)
catalytic hydrogenation
b)
treatment with LiAlH4
c)
treatment with pyridi... read moreJEE-Main - Grade 12 - Chemistry - Alcohols, Phenols and Ethers - Study ref# 9945Out of o-nitro-phenol and p-nitro-phenol,
which is more volatile? Answer: o-nitrophenol is more volatile than
p-nitrophenol due to presence of intramolecular hydrogen bonding. in para
nitrophenol intermolecular hydrogen bonding is present. T... read moreJEE-Main - Grade 12 - Chemistry - Alcohols, Phenols and Ethers - Study ref# 9951Preparation of alcohols from alkenes from
involves the electrophilic attack on alkene carbon atom. Explain its
mechanism. Answer: Preparation of alcohols from alkene by
the hydration of alkenes in presence of sulphuric acid.
read moreJEE-Main - Grade 12 - Chemistry - Alcohols, Phenols and Ethers - Study ref# 9954Write steps to carry out the conversion
of phenol to aspirin. Answer: Aspirin can be prepared by the reaction
of salicylic with acetic anhydride. Salicylic acid is prepared by the
reaction of phenol with CO2 and NaOH.
This process is know... read moreJEE-Main - Grade 12 - Chemistry - Aldehydes, Ketones, Carboxylic Acids - Study ref# 9964The reagent which does not react with
both, acetone and benzaldehyde?
(a) Sodium hydrogen sulphite (b)
Phenyl hydrazine
(c) Fehling’s
solution (d) Grignard reagent Answer: (c) Acetone and benzaldehyde both... read moreJEE-Main - Grade 12 - Chemistry - Aldehydes, Ketones, Carboxylic Acids - Study ref# 9965Cannizzaro’s reaction is not given by……..
Answer: (d) Necessary condition for Cannizzaro
reaction is absence of hydrogen
atom. So, will
not give Cannizzaro reaction while other three compounds have no -hydrogen.
Hence, they... read moreJEE-Main - Grade 12 - Chemistry - Aldehydes, Ketones, Carboxylic Acids - Study ref# 9966Which products is formed when the
compound is
treated with concentrated aqueous KOH solution?
Answer: (b) Benzaldehyde is an aromatic aldehyde
having no α
hydrogen. So, on reaction with aqueous KOH solution
it undergoes Canniz... read moreJEE-Main - Grade 12 - Chemistry - Aldehydes, Ketones, Carboxylic Acids - Study ref# 9970Which of the following compounds do not undergo
aldol condensation?
Answer: (b, d)
Necessary condition for aldol
condensation is the presence of atleast one αH-atom.
Hence, and
do
not undergo aldol condensation as the both... read moreJEE-Main - Grade 12 - Chemistry - Aldehydes, Ketones, Carboxylic Acids - Study ref# 9979Why are carboxylic acids more acidic than
alcohols or phenols although all of them have hydrogen atom attached to an
oxygen atom ?
Answer: Carboxylic acids are more acidic than
alcohol or phenol, although all of them have read moreJEE-Main - Grade 12 - Chemistry - Aldehydes, Ketones, Carboxylic Acids - Study ref# 9984When liquid ‘A’ is treated with a freshly
prepared ammoniacal silver nitrate solution it gives bright silver mirror. The
liquid forms a white crystalline solid on treatment with sodium hydrogen
sulphite. Liquid ‘B’ also forms a white crystal... read moreJEE-Main - Grade 12 - Chemistry - Biomolecules - Study ref# 10018In fibrous proteins, polypeptide chains
are held together by….. .
(a) van der Waals
forces (b) disulphide linkage
(c) electrostatic forces of
attraction (d) hydrogen bonds Answer: (b, d)
In ... read moreJEE-Main - Grade 12 - Chemistry - Biomolecules - Study ref# 10024Α-helix is a secondary structure of proteins formed by twisting of
polypeptide chain into right handed screw like structure. Which type of
interactions are responsible for making the α-helix
structure stable? Answer: 𝛂-
... read moreJEE-Main - Grade 12 - Chemistry - Biomolecules - Study ref# 10025During curdling of milk, what happens to
sugar present in it? Answer: Curdling of milk is caused due to
formation of lactic acid by the bacteria present in milk. It is an example of
denaturation of protein, i.e., when a protein is subjected ... read moreJEE-Main - Grade 12 - Chemistry - Biomolecules - Study ref# 10031Coagulation of egg white on boiling is an
example of denaturation of protein. Explain it in terms of structural
changes. Answer: Denuturation of proteins Protein present in egg white has a unique three dimensional
structure. When it is subje... read moreJEE-Main - Grade 12 - Chemistry - Polymers - Study ref# 10053Which factor imparts crystalline nature
to a polymer like nylon? Answer: Strong intermolecular forces like
hydrogen bonding and linear structure that lead to close packing of chains
and hence, imparts crystalline character e.g., nylon.... read moreJEE-Main - Grade 12 - Chemistry - Chemistry in Everyday Life - Study ref# 10071Which of the following are not used as
food preservatives?
(a) Table salt (b)
Sodium hydrogencarbonate
(c) Cane sugar (d) Benzoic
acid Answer: (b, c)
Food preservatives prevent spoilage of food
du... read moreJEE-Main - Grade 12 - Chemistry - Chemistry in Everyday Life - Study ref# 10081Which site of an enzyme is called
allosteric site? Answer: Sites different from active site of
enzyme where a molecule can bind and change the shape of the active site is
called allosteric site.
Detailed Explanation :
Drugs can bloc... read moreJEE-Main - Grade 12 - Physics - Electrostatic Potential and Capacitance - Study ref# 10483In a hydrogen atom, the electron and
proton are bound at a distance of about 0.53.
(a) Estimate the potential energy of the
system in eV, taking the zero of the potential energy at infinite... read moreJEE-Main - Grade 12 - Physics - Atoms - Study ref# 10654When is line
of the Balmer series in the emission spectrum of hydrogen atom obtained? Answer: line
of the Balmer series in the emission spe... read moreJEE-Main - Grade 12 - Physics - Atoms - Study ref# 10655What is the maximum number of spectral
lines emitted by a hydrogen atom when it is in the third excited state?
Answer: If n is the quantum number of highest
energy level, then the total number of possible spectral lines emitted is
... read moreJEE-Main - Grade 12 - Physics - Atoms - Study ref# 10659Calculate the de-Broglie wavelength of
the electron orbiting in the n=2 state of hydrogen atom. Answer: Kinetic Energy for the second state
read moreJEE-Main - Grade 12 - Physics - Atoms - Study ref# 10660Using Rutherford model of the atom,
derive the expression for the total energy of the electron in hydrogen atom. What
is the significance of the total negative energy possessed by the electron? Answer: For hydrogen atom
The coulomb force pro... read moreJEE-Main - Grade 12 - Physics - Atoms - Study ref# 10661Using Bohr’s postulates, derive the
expression for the orbital period of the electron moving in the orbital of hydrogen atom. Answer: …Bohr postulate
Also,
... read moreJEE-Main - Grade 12 - Physics - Nuclei - Study ref# 10675The gravitational force between a H-atom
and another particle of mass m will be given by Newton’s law:
(a)
(b) read moreJEE-Main - Grade 12 - Physics - Nuclei - Study ref# 10681Heavy water is a suitable moderator in a
nuclear reactor. Explain briefly why? Answer: The moderator is used in nuclear reactor
to reduce the velocity of neutrons so that it can break the uranium nucleus.
Heavy water which has heavy hydrogen... read more
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