datavorous/entrance-exam-dataset huggingface dataset:
Which one is a nucleophilic substitution reaction among the following?

Options:
A

B

C

D

The correct answer is:

Solution:

Topic: Chemistry, Haloalkanes and Haloarenes, NEET, NEET 2011 (Screening)
Which one is a reducing sugar?

Options:
A Galactose
B Gluconic acid
C $\beta$ Methyl galactoside
D Sucrose

The correct answer is:
Galactose

Solution:
All those carbohydrates which contain a free aldehyde or ketonic group and reduce Fehling's solution and Tollen's reagent are referred as a reducing sugar. Examples of reducing sugar are galactose, glucose, glyceraldehyde, fructose, ribose, and xylose.
Non-reducing sugars do not have an $\mathrm{OH}$ group attached to the anomeric carbon so they cannot reduce other compounds. All monosaccharides such as glucose are reducing sugars. Examples Sucrose, Trehalose, Raffinose, Stachyose.
A Caution
$\Rightarrow$ The anomeric carbon is the carbon derived from the carbonyl carbon compound (the ketone or aldehyde functional group) of the open-chain form of the carbohydrate molecule. The anomeric carbon can be determined by the carbon attached to two oxygen atoms joined by single bonds.

Topic: Biology, Biomolecules (B), NEET, NEET 2002
Which one is a wrong statement?

Options:
A The electronic configuration of N atom is,

B An orbital is designated by three quantum numbers, while an electron in an atom is designated by four quantum numbers.
C Total orbital angular momentum of electron in 's' orbital is equal to zero.
D The value of m for dz2 is zero.

The correct answer is:
The electronic configuration of N atom is,

Solution:
Electronic configuration of N

He2s2, 2p3

The correct configuration of 'N' is,

According to Hunds' rule, the electron first singly occupied in parallel, then anti-parallel in any particular orbital. In the given option, the last electron of P-orbital is in downwards spin. So, option 1 is incorrect.

Orbital angular momentum of any orbital,

L=l l+1 . h2πFor S-orbital, l value =0So, L = 0

Topic: Chemistry, Structure of Atom, NEET, NEET 2018
Which one is a wrong statement?

Options:
A The electronic configuration of N atom is

B An orbital is designated by three quantum numbers while an electron in an atom is designated by four quantum numbers.
C Total orbital angular momentum of electron in ‘s’ orbital is equal to zero.
D The value of m for dz2 is zero.

The correct answer is:
The electronic configuration of N atom is

Solution:
According to Hund’s Rule of maximum multiplicity, the correct electronic configuration of N-atom is

Hence, option (a) violates Hund’s rule. Rest other options are correct.

Topic: Chemistry, Structure of Atom, NEET
Which one is an example of a biennial and monocarpic plant?

Options:
A Wheat
B Agave
C Sugarbeet
D Banana

The correct answer is:
Sugarbeet

Solution:
Biennials are monocarpic plants that normally flower and die in the second season. Sugarbeet, cabbages, carrots are some of the common biennials. Subjecting the growing of a biennial plant to a cold treatment stimulates a subsequent photoperiodic flowering response.

Topic: Biology, Plant - Growth and Development, NEET
Which one is an example of heterogenous catalysis?

Options:
A Combination between dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron.
B Oxidation of sulphur dioxide into sulphur trioxide in the presence of oxides of nitrogen.
C Hydrolysis of sugar catalysed by H+ ions.
D Decomposition of ozone in presence of nitrogen monoxide.

The correct answer is:
Combination between dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron.

Solution:
Heterogeneous catalysis is catalysis where the phase of catalysts differs from that of the reactants or products. Combination between dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron is a heterogenous catalysis because iron is solid catalyst and reactants and products are gases.

Topic: Chemistry, Surface Chemistry, NEET, NEET 2023 (All India)
Which one is an important constituent of the renin-angiotensinogen-aldosterone system?

Options:
A Juxtaglomerular apparatus
B Bowman's capsule
C Loop of Henle
D Glomerulus

The correct answer is:
Juxtaglomerular apparatus

Solution:
The Juxtaglomerular apparatus (JGA) plays a complex regulatory role. A fall in glomerular blood flow/glomerular blood pressure/GFR can activate the JG cells to release renin which converts angiotensinogen in the blood to angiotensin I and further to angiotensin II. Angiotensin II, being a powerful vasoconstrictor increases the glomerular blood pressure and thereby GFR. Angiotensin II also activates the adrenal cortex to release aldosterone. Aldosterone causes reabsorption of Na+ and water from the distal parts of the tubule. This also leads to an increase in blood pressure and GFR. This complex mechanism is generally known as the Renin-Angiotensin mechanism.

Topic: Biology, Excretory Products and their Elimination, NEET
Which one is correct regarding thermal stability of hydrides of group 15?

Options:
A NH3>PH3>AsH3
B PH3>NH3>AsH3
C NH3>AsH3>PH3
D AsH3>PH3>NH3

The correct answer is:
NH3>PH3>AsH3

Solution:
Thermal stability is the property of a compound to resist break down of the bond under heating effect.
Bond energy is the amount of energy required to break the bond in the molecule.

Therefore, higher the bond energy, higher is the thermal stability.

Thermal stability is directly proportional to the bond energy and inversely proportional to the bond length.

Bond length increases down the group due to increasing the atomic radius by increasing the number of inner shell.

As the bond length increases bond energy and thermal stability decreases down the group.

[ ∵ Bond energy N−H>P−H>AS−H]

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Which one is electron deficient compound?

Options:
A NH3
B BCl3
C PCl3
D ICl

The correct answer is:
ICl

Solution:
No. of electrons in valance shell of B=6e-
So, octet is incomplete.

Topic: Chemistry, Chemical Bonding and Molecular Structure, NEET
Which one is incorrect about ecological pyramids?

Options:
A

Number	Biomass	Energy

Lake

B

Number	Biomass	Energy

Grassland

C

Number	Biomass	Energy

Ocean

D

Number	Biomass	Energy

Tree

The correct answer is:

Number	Biomass	Energy

Ocean

Solution:
In the aquatic ecosystem, such as large lakes and oceans, the pyramid of biomass is inverted instead of upright because microscopic phytoplankton are primary producers and being single-celled organisms, they do not accumulate much biomass.

Topic: Biology, Ecosystem, NEET
Which one is incorrect statement?

Options:
A He is used in gas cooled nuclear reactors
B He is used as a cryogenic agent for carrying out experiments at low temperature
C He is used to produce and sustain powerful super conducting magnets
D He is used to fill gas balloons instead of H2 because it is lighter than H2 and non-inflammable

The correct answer is:
He is used to fill gas balloons instead of H2 because it is lighter than H2 and non-inflammable

Solution:
He is used to fill gas balloons as it is lighter and non-inflammable,
But H2 is lighter than helium.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Which one is known as tear gas?

Options:
A COCl2
B CH3Cl
C CH3COCl
D CCl3NO2

The correct answer is:
CCl3NO2

Solution:
Tear gas is CCl3NO2 which is formed by the nitration of chloroform as follows
CHCl3+HNO3âCCl3NO2Chloro picrinor tear gas+H2O

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Which one is malachite from the following?

Options:
A CuFeS2
B CuOH2
C Fe3O4
D CuCO3.CuOH2

The correct answer is:
CuCO3.CuOH2

Solution:
Malachite is a green copper carbonate hydroxide mineral with the chemical formula CuCO3.CuOH2

Topic: Chemistry, General Principles and Processes of Isolation of Metals, NEET, NEET 2019 (All India)
Which one is most reactive towards an electrophilic reagent?

Options:
A
B
C
D

The correct answer is:

Solution:
Here is most reactive for the attack of electrophile as both –OH and -CH3 groups are ring activating as they increase electron density on ortho and para positions.

Topic: Chemistry, General Organic Chemistry, NEET
Which one is most reactive towards electrophilic reagent?

Options:
A

B

C

D

The correct answer is:

Solution:
Key Idea Electron withdrawing substituent deactivates the benzene nucleus towards electrophilic substitution while electron releasing substituent activates the ring towards electrophilic substitution.
Among the given, $-\mathrm{OH}$ has the higher electron donating tendency and thus, activates the ring more towards electrophilic substitution. Hence, is more reactive towards electrophilic reagent.

Topic: Chemistry, Haloalkanes and Haloarenes, NEET, NEET 2010 (Screening)
Which one is most reactive towards Nucleophilic addition reaction?

Options:
A
B
C
D

The correct answer is:

Solution:
Electron withdrawing -I, -M groups increases reactivity towards nucleophilic addition reaction.
In NO2-I,-M group increases the reactivity towards nucleophilic addition reaction at CHO group.

Topic: Chemistry, Carboxylic Acid Derivatives, NEET
Which one is most reactive towards Nucleophilic addition reaction?

Options:
A
B
C
D

The correct answer is:

Solution:
Electron withdrawing -I, -M groups increases reactivity towards nucleophilic addition reaction.
In NO2-I,-M group increases the reactivity towards nucleophilic addition reaction at CHO group.

Topic: Chemistry, Aldehydes and Ketones, NEET, NEET 2014
Which one is most reactive towards Nucleophilic addition reaction?

Options:
A
B
C
D

The correct answer is:

Solution:
Reactivity of carbonyl compounds towards NAR depends on steric and electronic effects.
Reactivity ∝ E.W.G. (Electron withdrawing group) ∝1sterichindrance
NAR reactivity

increase (+)ve charge on sp2c of -C||O-

Topic: Chemistry, Aldehydes and Ketones, NEET
Which one is most reactive towards $\mathrm{S}_{\mathrm{N}} 1$ reaction?

Options:
A $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}\left(\mathrm{C}_6 \mathrm{H}_5\right) \mathrm{Br}$
B $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}\left(\mathrm{CH}_3\right) \mathrm{Br}$
C $\mathrm{C}_6 \mathrm{H}_5 \mathrm{C}\left(\mathrm{CH}_3\right)\left(\mathrm{C}_6 \mathrm{H}_5\right) \mathrm{Br}$
D $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}_2 \mathrm{Br}$

The correct answer is:
$\mathrm{C}_6 \mathrm{H}_5 \mathrm{C}\left(\mathrm{CH}_3\right)\left(\mathrm{C}_6 \mathrm{H}_5\right) \mathrm{Br}$

Solution:
Key Idea $S_{\mathrm{N}} 1$ reaction involves the formation of carbocation intermediate. More the stability of carbocation, more is the reactivity of alkyl/aryl halides towards $\mathrm{S}_{\mathrm{N}} 1$ reaction.
The intermediate carbocations formed by given halides are as :
(a) $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}\left(\mathrm{C}_6 \mathrm{H}_5\right) \mathrm{Br} \longrightarrow\left(\mathrm{C}_6 \mathrm{H}_5\right)_2 \stackrel{+}{\mathrm{C}} \mathrm{H}+\mathrm{Br}^{-}$
(b) $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}\left(\mathrm{CH}_3\right) \mathrm{Br} \longrightarrow \mathrm{C}_6 \mathrm{H}_5 \stackrel{+}{\mathrm{C}} \mathrm{H}\left(\mathrm{CH}_3\right)+\mathrm{Br}^{-}$
(c) $\mathrm{C}_6 \mathrm{H}_5 \mathrm{C}\left(\mathrm{CH}_3\right)\left(\mathrm{C}_6 \mathrm{H}_5\right) \mathrm{Br} \longrightarrow$
$$
\left(\mathrm{C}_6 \mathrm{H}_5\right)_2 \stackrel{+}{\mathrm{C}}\left(\mathrm{CH}_3\right)+\mathrm{Br}^{-}
$$
(d) $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}_2 \mathrm{Br} \longrightarrow \mathrm{C}_6 \mathrm{H}_5 \stackrel{+}{\mathrm{C}} \mathrm{H}_2+\mathrm{Br}^{-}$
The order of stability of these carbocations is as
$$
\begin{aligned}
\left(\mathrm{C}_6 \mathrm{H}_5\right)_2 \stackrel{+}{\mathrm{C}}\left(\mathrm{CH}_3\right) & >\left(\mathrm{C}_6 \mathrm{H}_5\right)_2 \stackrel{+}{\mathrm{C}} \mathrm{H} \\
& >\mathrm{C}_6 \mathrm{H}_5 \stackrel{+}{\mathrm{C}} \mathrm{H}\left(\mathrm{CH}_3\right)>\mathrm{C}_6 \mathrm{H}_5 \stackrel{+}{\mathrm{C}} \mathrm{H}_2
\end{aligned}
$$
Thus, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{C}\left(\mathrm{CH}_3\right)\left(\mathrm{C}_6 \mathrm{H}_5\right) \mathrm{Br}$ is most reactive towards $\mathrm{S}_{\mathrm{N}} 1$ reaction.

Topic: Chemistry, Haloalkanes and Haloarenes, NEET, NEET 2010 (Screening)
Which one is most reactive towards SN1 reaction?

Options:
A C6H5CH2Br
B C6H5CH(C6H5)Br
C C6H5CH(CH3)Br
D C6H5C(CH3)(C6H5)Br

The correct answer is:
C6H5C(CH3)(C6H5)Br

Solution:
C 6 H 5 2 C ⊕ CH 3 >  C 6 H 5 2 C ⊕ CH
C 6 H 5 − C ⊕ − CH 3 >  C 6 H 5 − C ⊕ H 2
Reactivity for SN1 reaction depends on stability of carbocation
Stability of carbocation â charge delocalization â hence stability of carbocation is
4>2>3>1
Reactivity for SN1â stability of carbocation
i.e. (C6H5)CCH3(D)>(C6H5)2CH(B)>C6H5C(CH3)(C)>C6H5CH2(A)

Topic: Chemistry, Haloalkanes and Haloarenes, NEET
Which one is most stable to heat?

Options:
A HCIO
B HClO2
C HClO3
D HClO4

The correct answer is:
HClO4

Solution:
As the oxidation state of the halogen atom increases, the halogen-oxygen bond becomes more and more covalent. As a result, the thermal stability of the oxo acid increases. Thus, HClO4 is most stable to heat; whereas HClO is least stable to heat.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Which one is not a resonance form of a phenolate ion?

Options:
A
B
C
D

The correct answer is:

Solution:
It has a pentavalent carbon so this structure is not permissible. Rest all other are correct.

Topic: Chemistry, General Organic Chemistry, NEET
Which one is not correct mathematical equation for Dalton's Law of partial pressure? Here P= total pressure of gaseous mixture

Options:
A P=n1RTV+n2RTV+n3RTV
B Pi=XiP, where Pi= partial pressure of ith gas
Xi= mole fraction ith gas in gaseous mixture
C Pi=XiPio, where Xi= mole fraction of ith gas in gaseous mixture
Pio= pressure of ith gas in pure state
D P=P1+P2+P3

The correct answer is:
Pi=XiPio, where Xi= mole fraction of ith gas in gaseous mixture
Pio= pressure of ith gas in pure state

Solution:
Dalton’s law of partial pressures is a gas law which states that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures exerted by each individual gas in the mixture.

P=P1+P2+P3

P1, P2 and P3 are the partial pressures and P is the total pressure.

According to ideal gas equation

P1=n1RTV, P2=n2RTV and P3=n3RTV

Partial pressure of the individual gas can be expressed as follows,

Pi=XiP, P is total pressure.

Topic: Chemistry, States of Matter, NEET, NEET 2022 (Phase 1)
Which one is the cofactor of carboxypeptidase?

Options:
A Iron
B Zinc
C Copper
D Magnesium

The correct answer is:
Zinc

Solution:
A number of enzymes require metal ions for their activity which form coordination bonds with side chains at the active site and at the same time form one or more coordination bonds with the substrate, e.g., zinc is a cofactor for the proteolytic enzyme carboxypeptidase. Catalytic activity is lost when the co-factor is removed from the enzyme which testifies that they play a crucial role in the catalytic activity of the enzyme.

Topic: Chemistry, Biomolecules, NEET
Which one is the correct order of acidity?

Options:
A CH≡CH>CH3-C≡CH>CH2=CH2>CH3-CH3
B CH≡CH>CH2=CH2>CH3-C≡CH>CH3-CH3
C CH3-CH3>CH2=CH2>CH3-C≡CH>CH≡CH
D CH2=CH2>CH3-CH=CH2>CH3-C=CH>CH≡CH

The correct answer is:
CH≡CH>CH3-C≡CH>CH2=CH2>CH3-CH3

Solution:
Solution; Acidic nature ∝s%∝1+I
CHs%≡CH50%sp>CH3+I-C≡CH50%sp>CH2=CH233%sp>CH3-CH325%sp

Topic: Chemistry, General Organic Chemistry, NEET
Which one is the correct product of DNA dependent RNA polymerase to the given template?
3'TACATGGCAAATATCCATTCA5

Options:
A 5'AUGUAAAGUUUAUAGGUAAGU3'
B 5'AUGUACCGUUUAUAGGGAAGU3'
C 5'ATGTACCGTTTATAGGTAAGT3'
D 5'AUGUACCGUUUAUAGGUAAGU3'

The correct answer is:
5'AUGUACCGUUUAUAGGUAAGU3'

Solution:
Template DNA is :
3'TACATGGCAAATATCCATTCA5'
5'AUGUACCGUUUAUAGGUAAGU3' m-RNA

Topic: Biology, Molecular Basis of Inheritance, NEET, NEET 2024
Which one is the most acidic compound?

Options:
A
B
C
D

The correct answer is:

Solution:
Acidic Nature ∝-I,-R∝1+I,+R
So

Topic: Chemistry, Alcohols Phenols and Ethers, NEET
Which one is the most likely structure of CrCl3 .6H2O, if 1/3 of total chlorine of the compound is precipitated by adding AgNO3 to its aqueous solution?

Options:
A CrCl 3 &CenterDot; 6 H 2 O
B Cr H 2 O 3 Cl 3 &CenterDot; 3 H 2 O
C Cr Cl 2 H 2 O 4 Cl · 2 H 2 O
D Cr Cl H 2 O 5 Cl 2 &CenterDot; H 2 O

The correct answer is:
Cr Cl 2 H 2 O 4 Cl · 2 H 2 O

Solution:
CrCl 3 Â· 6 H 2 O has 3âCl atoms but 1 3 Cl atoms precipitated so one 1âCl atom get precipitated.
According to Werner's theory, only those ions are precipitated which are attached to the metal atoms with ionic bonds and are present outside the co-ordination sphere.
Cr H 2 O 4 Cl 2 Clâ(aq)â Cr H 2 O 4 Cl 2 + aq + Cl â aq
Ag++Cl- â¶AgCl âwhite

Topic: Chemistry, Coordination Compounds, NEET
Which one is the wrong pairing for the disease and its causal organism?

Options:
A Late blight of potato-Alternaria solani
B Black rust of wheat-Puccinia graminis
C Loose smut of wheat-Ustilago nuda
D Root-knot of vegetables-Meloidogyne sp.

The correct answer is:
Late blight of potato-Alternaria solani

Solution:
The causative agent of late blight of potato is fungus Phytophthora infestans, class-Oomycetes, order-Peronosporales, family-Pythiaceae. In India, the late blight of potato is a seed born disease.

Topic: Biology, Biological Classification, NEET, NEET 2009 (Screening)
Which one is used in the production of insulin by genetic engineering?

Options:
A Saccharomyces cerevisiae
B Escherichia coli
C Agrobacterium tumefaciens
D Both (A) and (B)

The correct answer is:
Escherichia coli

Solution:
Genetically engineered human insulin is called humulin. In 1983, Eli Lily an American company prepared two DNA sequences corresponding to A and B cahins of human insulin and introduced them into plasmids of E. coli to produce insulin chains. Chain A and B were separately produced, extracted and combined by creating disulfide bonds to form human insulin.

Topic: Biology, Biotechnology and Its Applications, NEET
Which one is wrongly matched?

Options:
A Gemma cups - Marchantia
B Biflagellate zoospores - Brown algae
C Uniflagellate gametes - Polysiphonia
D Unicellular organism - Chlorella

The correct answer is:
Uniflagellate gametes - Polysiphonia

Solution:
Polysiphonia is a red alga. In it, sexual reproduction is of oogamous type. The male sex organ, spermatangium produces non-flagellate male gametes.
In brown algae, sexual reproduction varies from isogamy, anisogamy and oogamy. In isogamy and anisogamy, both the gametes are motile while in oogamy only male gametes are motile. These motile gametes have two unequal laterally attached flagella.
Chlorella is a unicellular organism. It is green algae belonging to class Chlorophyta. In Marchantia, gemma cups are found on its dorsal surface. It contains gemma which helps in vegetative propagation.

Topic: Biology, Plant Kingdom, NEET, NEET 2018
Which one of following is a wrong statement?

Options:
A The uncertainty principle is ΔE×Δt≥h/4π
B Half filled and fully filled orbitals have greater stability due to greater exchange energy, greater symmetry and more balanced arrangement.
C The energy of 2s orbital is less than the energy of 2p orbital in case of Hydrogen like atoms.
D De-Broglies’s wavelength is given by λ=hmv, where m = mass of the particle, v = group velocity of the particle.

The correct answer is:
The energy of 2s orbital is less than the energy of 2p orbital in case of Hydrogen like atoms.

Solution:
In case of Hydrogenic species is 1s < 2s = 2p < 3s = 3p = 3d
Hence 2s and 2p have same energy for Hydrogenic species.
The rest of the statements are correct.

Topic: Chemistry, Structure of Atom, NEET
Which one of following is complex V of the ETS of inner mitochondrial membrane?

Options:
A NADH Dehydrogenase
B Cytochrome oxidase
C Ubiquinone
D ATP synthase

The correct answer is:
ATP synthase

Solution:
When the electrons pass from one carrier to another via complex I to IV in the electron transport chain, they are coupled to ATP synthase (complex V) for the production of ATP from ADP and inorganic phosphate. The number of ATP molecules synthesised depends on the nature of the electron donor. Oxidation of one molecule of NADH gives rise to 3 molecules of ATP, while that of one molecule of FADH2 produces 2 molecules of ATP.

Topic: Biology, Respiration in Plants, NEET
Which one of following statements is not correct of sigma- and $\mathrm{Pi}-$ bonds formed between two carbon atoms?

Options:
A Sigma-bond is stronger than a pibond
B Bond energies of sigma-and pi-bonds are of the order of $264 \mathrm{~kJ} / \mathrm{mol}$ and $347 \mathrm{~kJ} / \mathrm{mol}$, respectively
C Free rotation of atoms about a sigmabond is allowed but not in case of a pi-bond
D Sigma bond determines the direction between carbon atoms but a pi-bond has no primary effect in the regard

The correct answer is:
Bond energies of sigma-and pi-bonds are of the order of $264 \mathrm{~kJ} / \mathrm{mol}$ and $347 \mathrm{~kJ} / \mathrm{mol}$, respectively

Solution:
Bond energies of sigma and pi-bonds are of the order of $264 \mathrm{~kJ} / \mathrm{mol}$ and $347 \mathrm{~kJ} / \mathrm{mol}$ respectively as bond energy of sigma bond is greater than pi bond.
Related Theory
A sigma bond is stronger because of the head to head overlapping, while a pi bond is weaker because of side to side overlapping. A sigma bond requires more energy to break than a pi bond does.

Topic: Chemistry, Chemical Bonding and Molecular Structure, NEET, NEET 2003
Which one of following statements is not true?

Options:
A Clean water would have a BOD value of 5 ppm
B Fluoride deficiency in drinking water is harmful. Soluble fluoride is often used to bring its concentration upto 1 ppm
C When the $\mathrm{pH}$ of rain water is higher than 6.5 , it is called acid rain
D Dissolved Oxygen (DO) in cold water can reach a concentration upto $10 \mathrm{ppm}$

The correct answer is:
When the $\mathrm{pH}$ of rain water is higher than 6.5 , it is called acid rain

Solution:
The acid rain happens when the $\mathrm{pH}$ of the water drops below 5.6.
Related Theory
The oxides of $\mathrm{N}_2, C$ and $S$ mix with water during the precipitation.
Non-metal axide $+\mathrm{H}_2 \mathrm{O} \rightarrow$ Acid
Thus the pH of water decreases and acid rain is formed.

Topic: Chemistry, Environmental Chemistry, NEET, NEET 2013 (Karnataka)
Which one of Mn3+, Cr3+, V3+and Ti3+is the most stable in aqueous solution?

Options:
A Ti3+
B V3+
C Mn3+
D Cr3+

The correct answer is:
Cr3+

Solution:
Correct Option is : (D)
Cr3+

Topic: Chemistry, d and f Block Elements, NEET
Which one of the alkali metals, forms only, the normal oxide, $\mathrm{M}_2 \mathrm{O}$ on heating in air?

Options:
A $\mathrm{Rb}$
B $\mathrm{K}$
C $\mathrm{Li}$
D $\mathrm{Na}$

The correct answer is:
$\mathrm{Li}$

Solution:
Li is the alkali metal which forms only normal oxide $\mathrm{Li}_2 \mathrm{O}$ when heated in air.
$2 \mathrm{Li}+\frac{1}{2} \mathrm{O}_2 \longrightarrow \mathrm{Li}_2 \mathrm{O}$
Sodium, when heated in air, forms peroxide while heavier alkali metals form superoxide as the major product.

Topic: Chemistry, s Block Elements, NEET, NEET 2012 (Screening)
Which one of the alkaline earth metal carbonates is thermally the most stable?

Options:
A MgCO3
B CaCO3
C SrCO3
D BaCO3

The correct answer is:
CaCO3

Solution:
Correct Option is : (B)
CaCO3

Topic: Chemistry, s Block Elements, NEET
Which one of the compounds behaves as an electrophile as well as a nucleophile?

Options:
A Acetone
B Cyanide ion
C Nitrite ion
D Sulphite ion

The correct answer is:
Acetone

Solution:
Organic compound in which electronegative atom is bonded with carbon by multiple bonds behaves as both an electrophile as well as a nucleophile

Polar structure behaves as electrophile as well as nucleophile.

Topic: Chemistry, General Organic Chemistry, NEET