datavorous/entrance-exam-dataset huggingface dataset:
What pressure (bar) of \(\mathrm{H}_2\) would be required to make emf of hydrogen electrode zero in pure water at \(25^{\circ} \mathrm{C}\) ?

Options:
A \(10^{-7}\)
B 0.5
C 1
D \(10^{-14}\)

The correct answer is:
\(10^{-14}\)

Solution:
$\begin{aligned} & 2 \mathrm{e}^{-}+2 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow \mathrm{H}_2(\mathrm{~g}) \\ & \mathrm{E}=\mathrm{E}^{\circ}-\frac{0.059}{\mathrm{n}} \log \frac{\mathrm{P}_{\mathrm{H}_2}}{\left[\mathrm{H}^{+}\right]^2} \\ & 0=0-\frac{0.059}{2} \log \frac{\mathrm{P}_{\mathrm{H}_2}}{\left(10^{-7}\right)^2} \\ & \log \frac{\mathrm{P}_{\mathrm{H}_2}}{\left(10^{-7}\right)^2}=0 \\ & \frac{\mathrm{P}_{\mathrm{H}_2}}{10^{-14}}=1 \\ & \mathrm{P}_{\mathrm{H}_2}=10^{-14} \text { bar }\end{aligned}$

Topic: Chemistry, Electrochemistry, JEE Main, JEE Main 2024 (04 Apr Shift 1)
What product is obtained on oxidation of I- with MnO4- in alkaline medium

Options:
A IO3-
B I2
C IO-
D IO4-

The correct answer is:
IO3-

Solution:
6MnO4-+I-+6OH-→6MnO42-+IO3-+3H2O

Topic: Chemistry, d and f Block Elements, JEE Main
What products are expected from the disproportionation reaction of hypochlorous acid?

Options:
A
$\mathrm{HClO}_3$ and $\mathrm{Cl}_2 \mathrm{O}$

B
$\mathrm{HClO}_2$ and $\mathrm{HClO}_4$

C
$\mathrm{HCl}$ and $\mathrm{Cl}_2 \mathrm{O}$

D
$\mathrm{HCl}$ and $\mathrm{HClO}_3$

The correct answer is:
$\mathrm{HCl}$ and $\mathrm{HClO}_3$

Solution:
No Solution Available

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), JEE Main, JEE Main 2006
What quantity (in mL) of a 45% acid solution of a mono-protic strong acid must be mixed with a 20% solution of the same acid to produce 800 mL of a 29.875% acid solution?

Options:
A 316
B 320
C 325
D 330

The correct answer is:
316

Solution:
V×45100+800-V20100=800×29.875100
9V20+160-V5=239
5V20=79⇒ V=316

Topic: Chemistry, Some Basic Concepts of Chemistry, JEE Main, JEE Main 2017 (09 Apr Online)
What remains intact in a protein during denaturation?

Options:
A Primary structure
B Secondary structure
C Tertiary structure
D Quaternary structure

The correct answer is:
Primary structure

Solution:
During denaturation, secondary and tertiary structures are destroyed, but the primary structure remains intact.

Topic: Chemistry, Biomolecules, NEET
What replaced cimetidine as the largest selling drug in the world for hyperacidity?

Options:
A Histamine
B Pepsin
C Hydrochloric acid
D Ranitidine (Zantac)

The correct answer is:
Ranitidine (Zantac)

Solution:
Cimetidine remained the largest selling drug until another drug, ranitidine (Zantac), was discovered.

Topic: Chemistry, Chemistry in Everyday Life, NEET
What represents the best method for converting a carboxylic acid to an aldehyde?

Options:
A Convert the acid to an acid chloride, and react the acid chloride with water.
B Reduce the acid with LiAlH4.
C Convert the acid to an acid chloride, and reduce the acid chloride with lithium aluminium tri(t-butoxy) hydride.
D Convert the acid to an acid chloride, react the acid chloride with a Grignard reagent, and reduce the product with LiAlH4.

The correct answer is:
Convert the acid to an acid chloride, and reduce the acid chloride with lithium aluminium tri(t-butoxy) hydride.

Solution:
(i) This method will not work
RCOOHâSOCl2/PCl3/PCl5RCOClâH2ORCOOH
Aldehyde will not form
(ii) Carboxylic acid are not reduced by LiAlH4.
(iii) This method is best
RCOOHâSOCl2/PCl3/PCl5RCOClâlithiumÂ aluminiumtrit-butoxyÂ hydride.RCHOaldehyde
(iv) This method will produce alcohol rather than aldehyde:
RCOOHâSOCl2/PCl3/PCl5RCOClâIR′MgBrRCOR′âLiAlH43Î¿alcohol

Topic: Chemistry, Carboxylic Acid Derivatives, JEE Main
What role do buffer solutions play in maintaining pH stability during experiments in laboratories?

Options:
A They accelerate reactions
B They change pH drastically
C They stabilize pH values
D They have no impact on pH

The correct answer is:
They stabilize pH values

Solution:
The paragraph doesn't explicitly mention acceleration of reactions but emphasizes that buffer solutions play a role in stabilizing pH values during experiments in laboratories.

Topic: Chemistry, Ionic Equilibrium, NEET
What role does platinum metal play in the decomposition of gaseous ammonia?

Options:
A It acts as a reactant.
B It acts as a product.
C It acts as a catalyst.
D It remains unchanged during the reaction.

The correct answer is:
It acts as a catalyst.

Solution:
Platinum metal acts as a catalyst in the mentioned reaction, facilitating the reaction without being consumed.

Topic: Chemistry, Chemical Kinetics, NEET
What sequence of reactions would best accomplish the following conversion?

Options:
A NaBH 4 /H 3 O +
B HOCH 2 CH 2 OH/H + ;   NaBH 4 ;   H + /H 2 O
C KMnO 4 /HO − ; heat
D LiAlH 4 /H 3 O +

The correct answer is:
HOCH 2 CH 2 OH/H + ;   NaBH 4 ;   H + /H 2 O

Solution:
It is possible as follows

Topic: Chemistry, Aldehydes and Ketones, JEE Main
What should be possible d-orbital energy levels of \( \mathrm{Ni} \) in \( \left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-} ? \)

Options:
A \( \mathrm{d}_{\mathrm{z}^{2}} < \mathrm{d}_{\mathrm{zx}} < \mathrm{d}_{\mathrm{xy}}=\mathrm{d}_{\mathrm{yz}} < \mathrm{d}_{\mathrm{x}^{2}-\mathrm{y}^{2}} \)
B \( \mathrm{d}_{\mathrm{x}^{2}-\mathrm{y}^{2}} < \mathrm{d}_{\mathrm{xy}} < \mathrm{d}_{\mathrm{z}^{2}} < \mathrm{d}_{\mathrm{xy}}=\mathrm{d}_{\mathrm{yz}} \)
C \( \mathrm{d}_{\mathrm{zx}}=\mathrm{d}_{\mathrm{yz}} < \mathrm{d}_{\mathrm{z}^{2}} < \mathrm{d}_{\mathrm{xy}} < \mathrm{d}_{\mathrm{x}^{2}-\mathrm{y}^{2}} \)
D \( \mathrm{d}_{\mathrm{z}^{2}} < \mathrm{d}_{\mathrm{xy}}=\mathrm{d}_{\mathrm{yz}} < \mathrm{d}_{\mathrm{xy}} < \mathrm{d}_{\mathrm{x}^{2}-\mathrm{y}^{2}} \)

The correct answer is:
\( \mathrm{d}_{\mathrm{zx}}=\mathrm{d}_{\mathrm{yz}} < \mathrm{d}_{\mathrm{z}^{2}} < \mathrm{d}_{\mathrm{xy}} < \mathrm{d}_{\mathrm{x}^{2}-\mathrm{y}^{2}} \)

Solution:
Square planar complex is formed by removal of ligand from z-axis in octahedral complex. So, ligands are present in x-y plane and directed towards axis. Therefore, orbitals which are pointed towards x and y axis encounters very high repulsion therefore, energy level of dx2-y2 is highest and dxy has lower energy because its lobes are at 45° from axis. dz2 has one third portion in xy plane so, its energy is higher than that of dzx and dyz. Energy of dzx=dyz, because they encounter same repulsion.

Thus, overall order of energy of d- orbitals are dzx=dyz<dz2<dxy<dx2-y2

Topic: Chemistry, Coordination Compounds, JEE Main
What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other

Options:
A $60^{=}$
B $90^{\circ}$
C $120^{\circ}$
D $175^{\circ}$

The correct answer is:
$90^{\circ}$

Solution:
The angle between the two plane mirrors should be B $90^{\circ}$. When two plane mirrors are placed at a right angle ( 90 degrees) to each other, the incident and reflected rays will always be parallel to each other, regardless of the angle of incidence. This is due to the properties of reflection and the geometry of the mirror setup.

Topic: Physics, Ray Optics, JEE Main
What should be the characteristic of fuse wire?

Options:
A High melting point, high specific resistance.
B Low melting point, low specific resistance.
C High melting point, low specific resistance.
D Low melting point, high specific resistance.

The correct answer is:
Low melting point, high specific resistance.

Solution:
Fuse wire should be such that it melts immediatley when strong current flows through the circuit. The same is possible if its melting point is low and resistivity is high.

Topic: Physics, Current Electricity, JEE Main
What should be the height of transmitting antenna and the population covered if the television telecast is to cover a radius of 150 km? The average population density around the tower is 2000 km-2 and the value of Re=6.5×106 m.

Options:
A Height =1731 m
Population Covered =1413×105
B Height =1241 m
Population Covered =7×105
C Height =1600 m
Population Covered =2×105
D Height =1800 m
Population Covered =1413×108

The correct answer is:
Height =1731 m
Population Covered =1413×105

Solution:
Radius covered, r=2RHT
150 km=2×6.5×106 mHT
150 km×1032=2×6.5×106HT
HT=1731 m

Population covered =πr22000 km-2
=3.14×(150)2×2000=1413×105

Topic: Physics, Communication System, JEE Main, JEE Main 2021 (22 Jul Shift 1)
What should be the lengths of a steel and copper rod at 0 Â°C so that the length of the steel rod is 5 cm longer than the copper rod at any temperature?

Î± (Steel) = 1.1 Ã10-5 â-1

Î± (Copper)= 1.7 Ã10-5 â-1

Options:
A 14.17 cm; 9.17 cm

B 9.17 cm, 14.17 cm
C 28.34 cm; 18.34 cm
D 14.17 cm, 18.34 cm

The correct answer is:
14.17 cm; 9.17 cm

Solution:
Here, αsteel= 1.1×10-5 ℃-1
αcopper=1.7×10-5 ℃-1
l0sl0c=αcαs= 1.7 ×10-51.1×10-5=1.545
∴ l0s=1.545l0c
Also, l0s-l0c=5
0.545l0c=5
l0c=50.545=9.17 cm
And l0s=1.545×9.17 cm =14.17 cm

Topic: Physics, Thermal Properties of Matter, JEE Main
What should be the order of arrangement of de-Broglie wavelength of electron λe, an α-particle λα and proton λp given that all have the same kinetic energy ?

Options:
A λe=λp=λα
B λe<λp<λα
C λe>λp>λα
D λe=λp>λα

The correct answer is:
λe>λp>λα

Solution:
λ=hp=h2mE∝1m

mα>mp>me

so λe>λp>λα

Topic: Physics, Dual Nature of Matter, JEE Main, JEE Main 2021 (25 Jul Shift 1)
What should be the velocity of an electron so that its momentum becomes equal to that of a photon of wavelength 5200 Aâ?

Options:
A 700 m s-1
B 1000 m s-1
C 1400 m s-1
D 2800 m s-1

The correct answer is:
1400 m s-1

Solution:
According to De Broglie's equation Momentum,
p= h Î»
or v=hmÎ»=6.62Ã10-349.1Ã10-31Ã5.2Ã10-7
=1.4Ã103 m s-1=1400 m s-1

Topic: Physics, Dual Nature of Matter, JEE Main
What substances exit from the tubules to maintain a concentration gradient in the medullary interstitium.

Options:
A Potassium and Urea
B Urea and Sodium Chloride
C Sodium and Potassium
D Sodium and Urea

The correct answer is:
Potassium and Urea

Solution:
The substances that exit from the tubules to maintain a concentration gradient in the medullary interstitium are urea and sodium chloride.

Topic: Biology, Excretory Products and their Elimination, NEET
What term is used to describe the small regions in a ferromagnetic substance where metal ions are grouped together?

Options:
A Clusters
B Aggregates
C Domains
D Lattices

The correct answer is:
Domains

Solution:
In a ferromagnetic substance, the small regions where metal ions are grouped together are called domains.

Topic: Chemistry, Solid State, NEET
What trend in reactivity is observed within a group of non-metals, such as halogens?

Options:
A Reactivity increases down the group
B Reactivity remains constant within the group
C Reactivity decreases down the group
D Reactivity is unpredictable within the group

The correct answer is:
Reactivity decreases down the group

Solution:
Within a group of non-metals, like halogens, reactivity decreases as you move down the group.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, NEET
What trend is observed in electronegativity values as you move from Si to Pb within group 14?

Options:
A Electronegativity increases
B Electronegativity decreases
C Electronegativity remains constant
D Electronegativity fluctuates unpredictably

The correct answer is:
Electronegativity remains constant

Solution:
The electronegativity values for elements from Si to Pb are almost the same,indicating that they remain constant within this group.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
What trend is observed in the acidic character of these hydrides from H2O to H2Te?

Options:
A The acidic character decreases
B The acidic character remains constant
C The acidic character increases
D The acidic character is not mentioned

The correct answer is:
The acidic character increases

Solution:
The paragraph states that the acidic character of these hydrides increases from H2O to H2Te.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
What type of alignment do domains in ferrimagnetic substances exhibit?

Options:
A All domains have their magnetic moments aligned in the same direction.
B All domains have their magnetic moments aligned in anti-parallel directions.
C Some domains have their magnetic moments aligned in parallel directions, while others have them aligned in anti-parallel directions.
D Domains do not have any alignment in ferrimagnetic substances.

The correct answer is:
Some domains have their magnetic moments aligned in parallel directions, while others have them aligned in anti-parallel directions.

Solution:
Domains in ferrimagnetic substances exhibit some alignment in parallel directions and some alignment in anti-parallel directions.

Topic: Chemistry, Solid State, NEET
What type of crystal defect is indicated in the diagram below
$\begin{array}{llllll}\mathrm{Na}^{+} & \mathrm{Cl}^{-} & \mathrm{Na}^{+} & \mathrm{Cl}^{-} & \mathrm{Na}^{+} & \mathrm{Cl}^{-} \\ \mathrm{Cl}^{-} & \square & \mathrm{Cl}^{-} & \mathrm{Na}^{+} & \square & \mathrm{Na}^{+} \\ \mathrm{Na}^{+} & \mathrm{Cl}^{-} & \square & \mathrm{Cl}^{-} & \mathrm{Na}^{+} & \mathrm{Cl}^{-} \\ \mathrm{Cl}^{-} & \mathrm{Na}^{+} & \mathrm{Cl}^{-} & \mathrm{Na}^{+} & \square & \mathrm{Na}^{+}\end{array}$

Options:
A Interstitial defect
B Schottky defect
C Frenkel defect
D Frenkel and Schottky defects

The correct answer is:
Schottky defect

Solution:
(b) In this diagram, equal number of cations $\left(\mathrm{Na}^{+}\right)$and anions $\left(\mathrm{Cl}^{-}\right)$are missing, so it, shows schottky defect.

Topic: Chemistry, Solid State, JEE Main
What type of crystal defect is indicated in the diagram below?
$\mathrm{Na}^{+} \mathrm{Cl}^{-} \mathrm{Na}^{+} \mathrm{Cl}^{-} \mathrm{Na}^{+} \mathrm{Cl}^{-}$
$\mathrm{Cl}^{-} \square \mathrm{Cl}^{-} \square \mathrm{Na}^{+} \square \mathrm{Na}^{+}$
$\mathrm{Na}^{+} \mathrm{Cl}^{-} \square \mathrm{Cl}^{-} \mathrm{Na}^{+} \mathrm{Cl}^{-}$
$\mathrm{Cl}^{-} \mathrm{Na}^{+} \mathrm{Cl}^{-} \mathrm{Na}^{+} \square \mathrm{Na}^{+}$

Options:
A
Frenkel defect

B
Frenkel and Schottky defects

C
Interstitial defect

D
Schottky defect

The correct answer is:
Schottky defect

Solution:
No Solution Available

Topic: Chemistry, Solid State, JEE Main, JEE Main 2004
What type of gas is produced in fermentation of dough, cheese making, and production of beverages?

Options:
A Carbon dioxide (CO₂)
B Methane
C Hydrogen (H₂)
D Oxygen (O₂)

The correct answer is:
Carbon dioxide (CO₂)

Solution:
In fermentation of dough, cheese making, and production of beverages, the main gas produced is CO₂.

Topic: Biology, Microbes in Human Welfare, NEET
What type of hormone is glucagon?

Options:
A Hyperglycemic hormone
B Hypoglycemic hormone
C Gluconeogenic hormone
D Lipolytic hormone

The correct answer is:
Hyperglycemic hormone

Solution:
Glucagon is a hyperglycemic hormone that acts mainly on the liver cells (hepatocytes) and stimulates glycogenolysis, gluconeogenesis, and reduces cellular glucose uptake and utilisation. This results in an increased blood sugar (hyperglycemia).

Topic: Biology, Chemical Coordination and Integration, NEET
What type of hybridisation is present in carbocation formed during the alkaline hydrolysis of 1- bromo -1- phenyl ethane?

Options:
A SP2
B SP
C d2SP3
D SP3

The correct answer is:
SP2

Solution:
Alkaline hydrolysis of 1- bromo -1- phenylethane produce 1- phenylethan – 1 – ol. The reaction proceed via SN1 reaction . A carbocation is formed in the slow step of an SN1 reaction. The positively charged carbon of the carbocation intermediate to an SP2- hybridised are in the same plane. Reaction involved is as follows:

Topic: Chemistry, Hydrocarbons, JEE Main
What type of hybridization is involved in \( \left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-} \) ?

Options:
A \( d^{2} s p^{3} \)
B dsp \( ^{2} \)
C \( \mathrm{sp}^{3} \mathrm{~d}^{2} \)
D \( \mathrm{dsp}^{3} \)

The correct answer is:
\( d^{2} s p^{3} \)

Solution:
Oxidation number of Fe in FeCN63- is +3 with Ar3d5 electronic configuration and by following the crystal field theory of octahedral complex, the electronic configuration is t2g2,1,1eg0,0 due to the strong field ligand CN-.

Hence, the hybridisation will be d2sp3, as two inner d-orbital complex are present.

Topic: Chemistry, Coordination Compounds, JEE Main
What type of orbital hybridisation is considered on $\mathrm{P}$ in $\mathrm{PCl}_5$ ?

Options:
A $\mathrm{sp}^3 \mathrm{~d}$
B $\mathrm{dsp}^3$
C $\mathrm{sp}^3 \mathrm{~d}^2$
D $\mathrm{d}^2 \mathrm{sp}^3$

The correct answer is:
$\mathrm{sp}^3 \mathrm{~d}$

Solution:
No Solution Available

Topic: Chemistry, Chemical Bonding and Molecular Structure, JEE Main
What type of reaction occurs when a glycol is treated with a strong dehydrating agent like $\mathrm{H}_2 \mathrm{SO}_4$ ?

Options:
A Oxidation
B Dehydration
C Reduction
D Hydrogenation

The correct answer is:
Dehydration

Solution:
Dehydration
Explanation: A strong dehydrating agent like sulfuric acid $\left(\mathrm{H}_2 \mathrm{SO}_4\right)$ can remove water (dehydrate) from a glycol, often leading to the formation of an alkene or a cyclic ether.

Topic: Chemistry, Alcohols Phenols and Ethers, JEE Main
What type of reactions are reverse reactions?

Options:
A Reactions that are unrelated to the main reaction.
B Reactions that occur simultaneously with the main reaction.
C Reactions that occur in the reverse order of the main reaction.
D Reactions that involve secondary reactants.

The correct answer is:
Reactions that occur in the reverse order of the main reaction.

Solution:
Reverse reactions are reactions that occur in the reverse order of the main reaction, often involving the conversion of products back to reactants.

Topic: Chemistry, Chemical Kinetics, NEET
What type of substances, like MnO, show antiferromagnetism?

Options:
A Ferromagnetic substances
B Paramagnetic substances
C Antiferromagnetic substances
D Diamagnetic substances

The correct answer is:
Antiferromagnetic substances

Solution:
Substances like MnO show antiferromagnetism, which is characterized by oppositely oriented domains that cancel out each other's magnetic moment.

Topic: Chemistry, Solid State, NEET
What type of substances would make better permanent magnets, ferromagnetic or ferrimagnetic. Justify your answer.

Options:

None

Solution:
Ferromagnetic substances make better permanent magnets. This is because when placed in magnetic field, their domains get oriented in the directions of magnetic field and a strong magnetic field is produced. This ordering of domains persists even when external magnetic field is removed. Hence, the ferromagnetic substance becomes a permanent magnet.

Topic: Chemistry, Solid State
What volume of hydrogen gas, at $273 \mathrm{~K}$ and $1 \mathrm{~atm}$, pressure will be consumed in obtaining $21.6 \mathrm{~g}$ of elemental boron (atomic mass $=10.8$ ) from the reducti on of boron trichloride by hydrogen?

Options:
A
$67.2 \mathrm{~L}$

B
$44.8 \mathrm{~L}$

C
$22.4 \mathrm{~L}$

D
$89.6 \mathrm{~L}$

The correct answer is:
$67.2 \mathrm{~L}$

Solution:
No. of moles of boron $=\frac{21.6}{10.8}=2$
for $\mathrm{BCl}_3$
$\therefore 1$ mole of Boron $=3$ mole of $\mathrm{Cl}$
$\therefore 2$ mole of Boron $=6$ mole of $\mathrm{Cl}$
$\mathrm{H}_2+\mathrm{Cl}_2 \rightarrow 2 \mathrm{HCI}$
$\Rightarrow 3$ moles of Hydrogen is required
$=3 \times 22.4=67.2$ Litre

Topic: Chemistry, Some Basic Concepts of Chemistry, JEE Main, JEE Main 2003
What volume of hydrogen in ml will be liberated at STP by the reaction of Zn on 50 ml of dilute H2SO4 of specific gravity 1.3 having purity of 40%?
Report your answer by rounding it upto nearest whole number.

Options:

The correct answer is:
6000

Solution:
Mass of H2SO4=50Ã13Ã40100=26 g
Zn+H2SO498 gor 1 moleâZnSO4-+H222.4 Lat NTP
As 98 gm H2SO4 provides =22.4 L H2
So 26 gm H2SO4 provides =22.4Ã2698
=5.95 L
â6 L

Topic: Chemistry, Some Basic Concepts of Chemistry, JEE Main
What volume of oxygen gas $\left(\mathrm{O}_2\right)$ measured at $0^{\circ} \mathrm{C}$ and 1 atm, is needed to burn completely $1 \mathrm{~L}$ of propane gas $\left(\mathrm{C}_3 \mathrm{H}_8\right)$ measured under the same conditions?

Options:
A $10 \mathrm{~L}$
B $7 \mathrm{~L}$
C $6 \mathrm{~L}$
D $5 \mathrm{~L}$

The correct answer is:
$5 \mathrm{~L}$

Solution:
$$
\begin{aligned}
& \underset{22.4 \mathrm{~L} \text { at STP }}{\mathrm{C}_3 \mathrm{H}_8(\mathrm{~g})}+\underset{5 \times 22.4 \mathrm{~L} \text { at STP }}{5 \mathrm{O}_2(\mathrm{~g})} \rightarrow 3 \mathrm{CO}_2(\mathrm{~g})+4 \mathrm{H}_2 \mathrm{O}(\mathrm{I}) \\
& \because 22.4 \mathrm{~L} \mathrm{C}_3 \mathrm{H}_8 \text { at STP } \equiv 5 \times 22.4 \mathrm{~L} \text { of } \mathrm{O}_2 \text { at STP } \\
& \therefore 1 \mathrm{LC}_3 \mathrm{H}_8 \text { at STP } \equiv \frac{5 \times 22.4}{22.4} \text { of } \mathrm{O}_2 \text { at STP } \\
& =5 \mathrm{~L} \text { of } \mathrm{O}_2 \text { at NTP } \\
&
\end{aligned}
$$

Topic: Chemistry, Some Basic Concepts of Chemistry, JEE Main
What volume of oxygen gas $\left(\mathrm{O}_2\right)$ measured at $0^{\circ} \mathrm{C}$ and 1 atm, is needed to burn completely $1 \mathrm{~L}$ of propane gas $\left(\mathrm{C}_3 \mathrm{H}_8\right)$ measured under the same conditions?

Options:
A $10 \mathrm{~L}$
B $7 \mathrm{~L}$
C $6 \mathrm{~L}$
D $5 \mathrm{~L}$

The correct answer is:
$5 \mathrm{~L}$

Solution:
$$
\begin{aligned}
& \underset{22.4 \mathrm{~L} \text { at STP }}{\mathrm{C}_3 \mathrm{H}_8(\mathrm{~g})}+\underset{5 \times 22.4 \mathrm{~L} \text { at STP }}{5 \mathrm{O}_2(\mathrm{~g})} \rightarrow 3 \mathrm{CO}_2(\mathrm{~g})+4 \mathrm{H}_2 \mathrm{O}(\mathrm{I}) \\
& \because 22.4 \mathrm{~L} \mathrm{C}_3 \mathrm{H}_8 \text { at STP } \equiv 5 \times 22.4 \mathrm{~L} \text { of } \mathrm{O}_2 \text { at STP } \\
& \therefore 1 \mathrm{LC}_3 \mathrm{H}_8 \text { at STP } \equiv \frac{5 \times 22.4}{22.4} \text { of } \mathrm{O}_2 \text { at STP } \\
& =5 \mathrm{~L} \text { of } \mathrm{O}_2 \text { at NTP } \\
&
\end{aligned}
$$

Topic: Chemistry, Some Basic Concepts of Chemistry, NEET, NEET 2008 (Mains)
What was one of the main weaknesses of the Bohr model that quantum mechanics addressed?

Options:
A Its complexity
B Its reliance on circular orbits
C Its inconsistency with wave-particle duality and the Heisenberg uncertainty principle
D Its inability to explain the structure of other atoms

The correct answer is:
Its inconsistency with wave-particle duality and the Heisenberg uncertainty principle

Solution:
One of the main weaknesses of the Bohr model was its inconsistency with wave-particle duality and the Heisenberg uncertainty principle, which quantum mechanics addressed.

Topic: Chemistry, Structure of Atom, NEET
What was the impact of increased health facilities and better living conditions on the growth of population in the last century?

Options:
A Decreased
B Remained unchanged
C Increased
D Marginal decrease

The correct answer is:
Increased

Solution:
In the last century, increased health facilities along with better living conditions had an explosive impact on the growth of population.

Topic: Biology, Reproductive Health, NEET
What was the main aim of T.W Engelmann's experiments on Cladophora?

Options:
A To discover the role of water in photosynthesis
B To determine the role of aerobic bacteria in photosynthesis
C To determine the main component of light that drives photosynthesis
D To determine the role of oxygen in photosynthesis

The correct answer is:
To determine the main component of light that drives photosynthesis

Solution:
T.W Engelmann’s main aim was to determine the main component of light that drives photosynthesis.

Topic: Biology, Photosynthesis in Higher Plants, NEET
What was the main basis for the earliest systems of classification within angiosperms?

Options:
A Habit and color
B Number and shape of leaves
C Androecium structure
D Natural affinities among the organisms

The correct answer is:
Androecium structure

Solution:
The earliest systems of classification within angiosperms were based mainly on the androecium structure, as given by Linnaeus.

Topic: Biology, Plant Kingdom, NEET