datavorous/entrance-exam-dataset huggingface dataset:
Asexual method of reproduction is the common method of reproduction in:

Options:
A Algae and Bryophyta
B Algae and Fungi
C All plants
D Algae, fungi and animals.

The correct answer is:
Algae and Fungi

Solution:
Asexual reproduction is simple and primitive method which occurs in organism with simple organization like algae and fungi. Asexual reproduction occurs by different types of spore formation occurs algae and fungi only.

Topic: Biology, Reproduction in Organisms, NEET
Asexual reproduction in fungus occurs by spores known as

Options:
A Conidiospores
B Sporangiospores
C Zoospores
D Any of the above

The correct answer is:
Any of the above

Solution:
Asexual reproduction in fungi occurs by endogenous spores like zoospore and sporangiospores and exogenous spores like conidia. Zoospores are flagellated and sporangiospores are non flagellated spores produced in sac-like structure called as sporangia. Conidia are produced exogenously in chains.

Topic: Biology, Reproduction in Organisms, NEET
Asexual reproduction in sponges occurs by

Options:
A Parthenogenesis
B Budding
C Fragmentation
D Spores

The correct answer is:
Fragmentation

Solution:
Sexual reproduction in sponges occurs by the formation of gametes. Sponges are hermaphrodites (sexes are not separate) but still perform cross-fertilization. Fertilization is internal, and development is indirect. The larva is free-swimming, however, the adult is sessile (fixed to substratum). Asexual reproduction in sponges occurs by the process of fragmentation.

Topic: Biology, Reproduction in Organisms, NEET
Asexual reproduction is common among all except:

Options:
A Unicellular organisms
B Plants with simple organization
C Animals with simple organization
D Animals with complex organization

The correct answer is:
Animals with complex organization

Solution:
Asexual reproduction is a common method of reproduction which occurs in unicellular organism, plants with simple organization like algae shows asexual reproduction by spore formation. Some animals with simple organisation reproduces asexually, but higher animals completely lacks asexual method of reproduction.

Topic: Biology, Reproduction in Organisms, NEET
Asexual reproduction is related to

Options:
A amphimixis
B budding
C vegetative propagation
D Both b and c

The correct answer is:
Both b and c

Solution:
Reproduction is the process of producing fertile offspring which look similar to parents. Sexual mode of reproduction is the reproductive process where two gametic cells fertilize or fuse to produce a zygote. In asexual reproduction, offspring is formed from a single parent without the formation of gametes. Sexual reproduction where gametes fuse to form a zygote is referred to as amphimixis.
Vegetative propagules are the plant parts or organs that are involved in the process of reproduction even though their primary function is not it. The reproductive process is called vegetative propagation as the non-reproductive parts/organs (leaf/stem/roots) are involved. It is a type of asexual reproduction.
In certain organisms, small buds are produced attached to the parent organism which grow and eventually separate to develop into new organism. This process is called budding and it is a type of asexual reproduction.

Topic: Biology, Reproduction in Organisms, NEET
Asexual reproduction takes place by zoospores or by aplanospores in:

Options:
A Colletotrichum
B Saccharomyces
C Rhizopus
D Alternaria

The correct answer is:
Rhizopus

Solution:
Members of phycomycetes are found in aquatic habitats and on decaying wood in the moist and damp places or as obligate parasites on plants. The mycelium is aseptate and coenocytic. Asexual reproduction takes place by zoospores (motile) or by aplanospores (non-motile). These spores are endogenously produced in sporangium. A zygospore is formed by fusion of two gametes. These gametes are similar in morphology (isogamous) or dissimilar (anisogamous or oogamous). Some common
examples are Mucor, Rhizopus, (the bread mould mentioned earlier) and Albugo (the parasitic fungi
on mustard).

Topic: Biology, Biological Classification, NEET
Ashwagandha and petunia belong to the family of

Options:
A Liliaceae
B Fabaceae
C Solanaceae
D Brassicaceae

The correct answer is:
Solanaceae

Solution:
Solanaceae: Many plants belonging to this family are a source of food (tomato, brinjal, potato), spice (chilli), medicine (belladonna, ashwagandha), and fumigatory (tobacco); ornamentals (petunia).

Topic: Biology, Morphology of Flowering Plants, NEET
Aspartame is unstable at cooking temperature, where would you suggest aspartame to be used for sweetening?

Options:
A Cold foods and Soft drinks.
B Warm foods.
C Hot drinks.
D High altitudes at very low temperatures.

The correct answer is:
Cold foods and Soft drinks.

Solution:
Correct Option is : (A)
Cold foods and Soft drinks.

Topic: Chemistry, Chemistry in Everyday Life, NEET
Aspirin is a pain relieving antipyretic drug but can be used to prevent heart attack. Explain.

Options:
A Aspirin has a direct analgesic effect on the heart.
B Aspirin reduces inflammation in the coronary arteries.
C Aspirin decreases blood flow to the heart muscle.
D Aspirin prevents platelet coagulation and thus has anti blood clotting action therefore can prevent blood clogging in the heart.

The correct answer is:
Aspirin prevents platelet coagulation and thus has anti blood clotting action therefore can prevent blood clogging in the heart.

Solution:
Correct Option is : (D)
Aspirin prevents platelet coagulation and thus has anti blood clotting action therefore can prevent blood clogging in the heart.

Topic: Chemistry, Chemistry in Everyday Life, NEET
Aspirin is chemically

Options:
A Methyl salicylate
B Ethyl salicylate
C Acetyl salicylic acid
D o-hydroxy benzoic acid

The correct answer is:
Acetyl salicylic acid

Solution:
Aspirin is an analgesic and chemically it is Acetyl Salicylic acid

Topic: Chemistry, Chemistry in Everyday Life, NEET
Assertion (A): A person goes to high altitude and experiences 'altitude sickness' with symptoms like breathing difficulty and heart palpitations.
Reason (R): Due to low atmospheric pressure at high altitude, the body does not get sufficient oxygen.
In the light of the above statements, choose the correct answer from the options given below.

Options:
A Both (A) and (R) are true and (R) is the correct explanation of (A)
B Both (A) and (R) are true but (R) is not the correct explanation of (A)
C (A) is true but (R) is false
D (A) is false but (R) is true

The correct answer is:
Both (A) and (R) are true and (R) is the correct explanation of (A)

Solution:
Altitude sickness (AMS) is experienced by a person at a high altitude where the body does not get enough oxygen due to low atmospheric pressure and causes nausea, fatigue and heart palpitations. Under these conditions, the body increases RBC production, decreases the binding capacity of haemoglobin and increases breathing rate. These physiological adaptations allow organisms to respond quickly to stressful conditions.

Topic: Biology, Organisms and Populations, NEET, NEET 2021
Assertion (A): The film which appears bright in reflected system will appear dark in the transmitted system and vice-versa.

Reason (R): The conditions for film to appear bright or dark in the reflected light are just reverse to those in the transmitted light

Options:
A A is true and R is true and R is the correct explanation of A .
B A and R are true but R is not the correct explanation of A
C A is true, R is false
D A is false, R is true.

The correct answer is:
A is true and R is true and R is the correct explanation of A .

Solution:
For reflected system of the film, the consition for maxima is 2μtcos⁡r=2n-1λ2 . While the maxima for transmitted system of film is 2μtcos⁡r=nλ and is reverse for minima. A & R are true and R is the correct explanation of A.

Topic: Physics, Wave Optics, NEET
Assertion: Average speed is equal to the magnitude of average velocity.

Reason: Displacement of body is less than or equal to distance.

Options:
A Both Assertion and Reason are true and the Reason is correct explanation of the Assertion.
B Both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
C Assertion is true but the Reason is false.
D Assertion is false but the Reason is true.

The correct answer is:
Assertion is false but the Reason is true.

Solution:
Since |Displacement|â¤Distance
â´|Displacement|timeâ¤Distancetime
|Average velocity|â¤Average speed

Topic: Physics, Motion In One Dimension, NEET
Assertion: Reduction factor k of a tangent galvanometer helps in reducing deflection of current.

Reason: As reduction factor increases with increase of current.

Options:
A If both Assertion and Reason are true and the Reason is correct explanation of the Assertion.
B If both Assertion and Reason are true but Reason is not explanation of the Assertion.
C If Assertion is true but the Reason is false.
D If Assertion is false but Reason is true.

The correct answer is:
If Assertion is true but the Reason is false.

Solution:
In tangent galvanometer current is directly proportional to the deflection and reduction factor helps in reducing reflection of the current.
The Reduction factor doesn't depend on current but on the construction of the instrument.
I=k ÏNBA
The assertion is true but the Reason is false.

Topic: Physics, Magnetic Properties of Matter, NEET
Assign the hybridization of boron in BH₃ and BF₃.

Options:
A BH₃: SP², BF₃: SP²
B BH₃: SP³, BF₃: SP²
C BH₃: SP², BF₃: SP³
D BH₃: SP³, BF₃: SP³

The correct answer is:
BH₃: SP², BF₃: SP²

Solution:
Correct Option is : (A)
BH₃: SP², BF₃: SP²

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Assign the IUPAC name for the following compound.

Options:
A 2-hydroxypentan-1,5-dioic acid
B 2-carboxy-2-hydroxypentan-1,5-dioic acid
C 2-hydroxypropan-1,2,3-tricarboxylic acid
D 3-hydroxypentan-1,2,3-trioic acid

The correct answer is:
2-hydroxypropan-1,2,3-tricarboxylic acid

Solution:
the IUPAC name for the following compound (citric acid) is 2-hydroxypropan-1,2,3-tricarboxylic acid

Topic: Chemistry, Carboxylic Acid Derivatives, NEET
Assign the position of the element having outer electronic configuration (n-1)d2ns2for n=4

Options:
A Element in Group 3, Period 4
B Element in Group 10, Period 4
C Element in Group 4, Period 4
D Element in Group 5, Period 4

The correct answer is:
Element in Group 4, Period 4

Solution:
Correct Option is : (C)
Element in Group 4, Period 4

Topic: Chemistry, Classification of Elements and Periodicity in Properties, NEET
Assign the position of the element having outer electronic configuration (n-2)f7(n-1)d1ns2for n=6

Options:
A Element in Group 3, Period 6
B Element in Group 5, Period 6
C Element in Group 6, Period 6
D Element in Group 7, Period 6

The correct answer is:
Element in Group 3, Period 6

Solution:
Correct Option is : (A)
Element in Group 3, Period 6

Topic: Chemistry, Classification of Elements and Periodicity in Properties, NEET
Assign the position of the element having the outer electronic configuration ns²np⁴ for n=3.

Options:
A Element in Group 14, Period 3
B Element in Group 15, Period 3
C Element in Group 16, Period 3
D Element in Group 17, Period 3

The correct answer is:
Element in Group 16, Period 3

Solution:
Correct Option is : (C)
Element in Group 16, Period 3

Topic: Chemistry, Classification of Elements and Periodicity in Properties, NEET
Associations between Mycobiont and Phycobiont are found in

Options:
A Mycorrhiza
B Root
C Lichens
D BGA

The correct answer is:
Lichens

Solution:
Associations between Mycobiont and Phycobiont are found in Lichens.

Topic: Biology, Biological Classification, NEET
Assume each reaction is carried out in an open container. For which reaction will $\Delta H=\Delta E ?$

Options:
A $2 \mathrm{CO}_{(\mathrm{g})}+\mathrm{O}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{CO}_{2(\mathrm{~g})}$
B $\mathrm{H}_{2(g)}+\mathrm{Br}_{2(g)} \rightarrow 2 \mathrm{HBr}_{(\mathrm{g})}$
C $\mathrm{C}_{(\mathrm{s})}+2 \mathrm{H}_2 \mathrm{O}_{(\mathrm{g})} \rightarrow 2 \mathrm{H}_{2(g)}+\mathrm{CO}_{2(g)}$
D $\mathrm{PCl}_{5(g)} \rightarrow \mathrm{PCl}_{3(g)}+\mathrm{Cl}_{2(g)}$

The correct answer is:
$\mathrm{H}_{2(g)}+\mathrm{Br}_{2(g)} \rightarrow 2 \mathrm{HBr}_{(\mathrm{g})}$

Solution:
$\mathrm{For}_2(g)+\mathrm{Br}_2(g) \rightarrow 2 \mathrm{HBr}(g)$
$$
\begin{array}{ll}
\because & \Delta n_g=0 \\
\therefore & \Delta \mathrm{H}=\Delta \mathrm{E}+\Delta n_g \mathrm{RT} \\
\Rightarrow & \Delta \mathrm{H}=\Delta \mathrm{E}
\end{array}
$$

Topic: Chemistry, Thermodynamics (C), NEET, NEET 2006
Assume each reaction is carried out in an open container. For which reaction will ∆H=∆E?

Options:
A Cs+2H2Og→2H2g+CO2g
B PCl5g→PCl3g+Cl2g
C 2COg+O2g→2CO2g
D H2g+Br2g→2HBrg

The correct answer is:
H2g+Br2g→2HBrg

Solution:
We know that
âH=âE+PâV
In the reactions, H 2 ( g )+ Br 2 ( g )â2HBr( g ) this is no change in volume or âV=0
So, âH=âE for this reaction

Topic: Chemistry, Thermodynamics (C), NEET
Assume that a lamp radiates power P uniformly in all directions. The magnitude of electric field strength at a distance r from the lamp is

Options:
A Pπcε0r2
B P2πcεr2
C P2ÏÎµ0r2c
D Pπε0cr2

The correct answer is:
P2πε0r2c

Solution:
Intensity, I=powerarea=P4πr2 = average energy density × velocity=12ε0E02c
∴E0=2P4πε0r2c=P2πε0r2c

Topic: Physics, Electromagnetic Waves, NEET
Assume that a particular amino acid has an isoelectric point of 6.0. In a solution at pH 1.0, which of the following species will predominate?

Options:
A
B
C
D

The correct answer is:

Solution:
In acidic medium Zwitter ion converts into

Topic: Chemistry, Biomolecules, NEET
Assume that light of wavelength 600 nm is coming from a star. The limit of resolution of telescope whose objective has a diameter of 2 m is:

Options:
A 1.83×10−7 rad
B 7.32×10−7 rad
C 6.00×10−7 rad
D 3.66×10−7 rad

The correct answer is:
3.66×10−7 rad

Solution:
Limit of resolution of a telescope is given by,

ϑmin=1.22λa, where λ is the wavelength of the light and a is the aperture diameter.

Given, λ=600 nm and a=2 m

ϑmin=1.22×6×10−72

⇒ϑmin=3.66×10−7 rad

Topic: Physics, Ray Optics, NEET, NEET 2020 (Phase 1)
Assume that there are 6 types of nitrogen bases are available and 37 types of an amino acid are available for protein synthesis. In genetic code, each codon will be made up of how many minimum number of nitrogen bases?

Options:
A 3
B 4
C 5
D 2

The correct answer is:
3

Solution:
If we consider codon to be of single nucleotide, they will only specify 6 amino acid out of 37. Hence, it can’t be a single nucleotide. A doublet code could code for 36 amino acids (6 x 6). A triple codon would code for 216 amino acids (6 X 6 X 6) and can provide plenty of information in the DNA molecule to specify the placement of all 37 amino acids. Hence, in this case, the codon has to be a triplet.

Topic: Biology, Molecular Basis of Inheritance, NEET
Assuming 2s â 2p mixing is NOT operative, which of the following is not diamagentic?

Options:
A Be2
B B2
C C2
D N2

The correct answer is:
C2

Solution:
If the given molecule/atom/ion has all paired electrons in its orbitals, then it is said to be diamagnetic and if atleast one of the orbital has unpaired electron, then it is said to be paramagnetic.

Writing the molecular orbital configuration of the given molecules assuming that no 2s-2p mixing takes place-
(i) Be2→σ1s2, σ*1s2, σ2s2, σ*2s2 (diamagnetic)
(ii) B2→σ1s2, σ*1s2, σ2s2, σ*2s2,σ2pz2 (diamagnetic)
(iii) C2→σ1s2, σ*1s2, σ2s2, σ*2s2, σ2pz2,π2px1π2py1 (paramagnetic)
(iv) N2→σ1s2, σ*1s2, σ2s2, σ*2s2, σ2pz2, π2px2π2py2 (diamagnetic)

Note here that, if any of the molecular orbital has two electrons, then the electrons will be paired and if it has one electron, then the electron will be unpaired.

Topic: Chemistry, Chemical Bonding and Molecular Structure, NEET
Assuming complete dissociation, calculate the pH of the following solutions (a) 0.003 M HCl (b) 0.005 M NaOH (c) 0.002 M HBr (d) 0.002 M KOH

Options:
A (a) pH = 2.52 (b) pH = 11.30 (c) pH = 2.70 (d) pH = 11.30
B (a) pH = 2.52 (b) pH = 11.70 (c) pH = 2.70 (d) pH = 11.70
C (a) pH = 2.30 (b) pH = 11.70 (c) pH = 2.70 (d) pH = 11.30
D (a) pH = 2.30 (b) pH = 11.30 (c) pH = 2.70 (d) pH = 11.30

The correct answer is:
(a) pH = 2.52 (b) pH = 11.30 (c) pH = 2.70 (d) pH = 11.30

Solution:
Correct Option is : (A)
(a) pH = 2.52 (b) pH = 11.30 (c) pH = 2.70 (d) pH = 11.30

Topic: Chemistry, Ionic Equilibrium, NEET
Assuming complete ionization, same moles of which of the following compounds will require the least amount of acidified KMnO4 for complete oxidation?

Options:
A FeSO4
B FeSO3
C FeC2O4
D FeNO22

The correct answer is:
FeSO4

Solution:
MnO4-⟶Mn2+ ; Change in oxidation no. = 5
In option,
i. Fe2+ ⟶Fe3+
Change in oxidation no. = 1
ii. Fe2+ ⟶Fe3+
Change in oxidation no. = 1
SO32-⟶SO42-
Change in oxidation no. = 2
=1+2=3
iii. Fe2+ ⟶Fe3+
Change in oxidation no. = 1
C2O42-⟶2CO2
Change in oxidation no. = 2
=1+2=3
iv. Fe2+ ⟶Fe3+
Change in oxidation no. = 1
2NO2-⟶2NO3-
Change in oxidation no. = 4
=1+4=5

Topic: Chemistry, Redox Reactions, NEET, NEET 2015 (Phase 2)
Assuming earth to be a sphere of radius R, if g' is the value of acceleration due to gravity at the latitude of 30Â° and g at the equator, the value of g-g' is

Options:
A 14ω2R
B 34ω2R
C ω2R
D 12ω2R

The correct answer is:
34ω2R

Solution:
The value of acceleration due to gravity at latitude λ is given by
gλ=g-Rω2cos2λ
∴ g-gλ=Rω2cos2λ
At λ=30°,
g-g'= Rω2cos230°
=Rω2322
=34Rω2

Topic: Physics, Gravitation, NEET
Assuming f to be the frequency of first-line in Balmer series, the frequency of the immediate next ( i.e. second) line is

Options:
A 0.50 f
B 1.35 f
C 2.05 f
D 2.70 f

The correct answer is:
1.35 f

Solution:
For Balmer series, nf=2 and ni=3,4,5....
Frequency, of 1st spectral line of Balmer series
f = RZ2 c122-132
or f=RZ2 c×536 ...(i)
Frequency, of 2nd spectral line of Balmer series
f’ = RZ2 c122-142
or f′=RZ2 c×316 ....(ii)
From equation. (i) and (ii), we have
ff′ =2027
∴ f′=2720 f=1.35 f

Topic: Physics, Atomic Physics, NEET
Assuming no change in volume, the time required to obtain solution of pH = 12 by electrolysis of 50 mL 0.1 M NaCl (using current of 0.5 amp) will be

Options:
A 65 sec
B 96.5 sec
C 965 sec
D 9.65 sec

The correct answer is:
96.5 sec

Solution:
[H+]=10-12M
So [OH-]=10-2M
Number of moles of NaOH in 50 mL solution
=MV1000=10-2×501000
=5×10-4
Mass of NaOH in the solution
=5×10-4×40=2×10-2g
W=ItE96500
2×10-2=0.5×t×4096500
t=96.5 sec.

Topic: Chemistry, Electrochemistry, NEET
Assuming that potential energy of spring is zero when it is stretched by x02, its potential energy when it is compressed by x0 is

Options:
A 38kx02
B -34kx02
C 34kx02​
D 18kx02

The correct answer is:
38kx02

Solution:
Change in potential energy is independent of reference
â´ U2-U1=12kx02-12kx022=38kx02

Topic: Physics, Work Power Energy, NEET
Assuming that the gravitational potential energy of an object at infinity is zero, the change in potential energy (final - initial) of an object of mass $m$, when taken to a height $\mathrm{h}$ from the surface of earth (of radius $\mathrm{R}$ ) is given by,

Options:
A $-\frac{G M m}{R+h}$
B $\frac{G M m h}{R(R+h)}$
C mgh
D $\frac{G M m}{R+h}$

The correct answer is:
$\frac{G M m h}{R(R+h)}$

Solution:
The gravitational potential energy of an object placed at earth's surface is
$$
\mathrm{U}_1=-\frac{\mathrm{GMm}}{\mathrm{R}}
$$
where, $G=$ gravitational constant,
$M=$ Mass of earth, $m=$ mass of object and
$\mathrm{R}=$ radius of the earth
The negative sign in the above relation indicates that it is the work done in bringing the object from infinity to a distance $R$.
The gravitational potential energy of object at a height habove the surface of earth is
$$
\mathrm{U}_2=-\frac{\mathrm{GMm}}{(\mathrm{R}+\mathrm{h})}
$$
So, the change in potential energy is
$$
\begin{aligned}
\Delta U & =\mathrm{U}_2-\mathrm{U}_1=-\frac{\mathrm{GMm}}{\mathrm{R}+\mathrm{h}}-\left(-\frac{\mathrm{GMm}}{\mathrm{R}}\right) \\
& =-\mathrm{GMm}\left[\frac{1}{(\mathrm{R}+\mathrm{h})}-\frac{1}{\mathrm{R}}\right]=-\mathrm{GMm}\left(-\frac{\mathrm{h}}{\mathrm{R}(\mathrm{R}+\mathrm{h})}\right) \\
& =\frac{\mathrm{GMmh}}{\mathrm{R}(\mathrm{R}+\mathrm{h})}
\end{aligned}
$$

Topic: Physics, Gravitation, NEET, NEET 2019 (Odisha)
Assuming that the potential energy of spring is zero when it is stretched by x0, then its potential energy when it is compressed by x02 is

Options:
A 38kx02
B -34kx02
C -38kx02
D 18kx02

The correct answer is:
-38kx02

Solution:
Change in potential energy is independent of frame of reference.
â´U2- U1 =12kx022- 12 kx02
=-38kx02

Topic: Physics, Work Power Energy, NEET
Assuming the Earth to be a sphere of uniform mass density, how much would a body weigh halfway down to the center of the Earth if it weighed 250 N on the surface?

Options:
A 250 N
B 125 N
C 62.5 N
D 31.25 N

The correct answer is:
125 N

Solution:
Correct Option is : (B)
125 N

Topic: Chemistry, Gravitation, NEET
Assuming the mass of Earth to be ten times the mass of Mars, its radius to be twice the radius of Mars and the acceleration due to gravity on the surface of Earth is 10 m/s2. Then the acceleration due to gravity on the surface of Mars is given by

Options:
A 0.4 m s-2
B 2 m s-2
C 4 m s-2
D 5 m s-2

The correct answer is:
4 m s-2

Solution:
Given, mass of earth =10ÃMm
Where, Mm= Mass of mars
Radius of earth =2 Rm
Where, Rm= radius of mars
And g=GMR2
Let gravity on the surface of mass is gm
â´ gmgE=MmMEÃRERm2
gm=geÃMmMERERm2
=10ÃMm10Mm2RmRm2=4 m/s2

Topic: Physics, Gravitation, NEET
Assuming the mass of the earth as 6.64Ã1024 kg and the average mass of the atoms that make up the earth as 40 u (atomic mass unit), the number of atoms in the earth is approximately

Options:
A 1030
B 1040
C 1050
D 1060

The correct answer is:
1050

Solution:
1 a.m.u=1 u=1.6 × 10-27 kg
40 u=40×1.6×10-27 kg
Number of atoms in earth,
=6.64 × 102440 ×1.6 ×10-27 = 1050

Topic: Physics, Atomic Physics, NEET
Assuming the sun to be a spherical body of radius R at a temperature of T K, evaluate the total radiant power, incident on earth, at a distance r from the sun. (r0 is the radius of the earth and σ is stefan's constant)

Options:
A 4πr02R2σT4/r2
B πr02R2σT4/r2
C r02R2σT4/4πr2
D R2σT4/r2

The correct answer is:
πr02R2σT4/r2

Solution:
From Stefan's law, the rate at which energy is radiated by sun at its surface is P=ÏÃ4ÏR2T4
[Sun is a perfect black body as it emits radiations of all wavelengths and so for it e=1]
The intensity of this power at earth's surface is
I= P 4Ï r 2 = ÏÃ4Ï R 2 T 4 4Ï r 2 = Ï R 2 T 4 r 2
The area of earth which receives this energy is only one-half of total surface area of earth, whose projection would be Ïr02.
â´ Total radiant power as received by earth
= Ïr02ÃI
= Ïr02ÃÏR2T4r2=Ïr02R2ÏT4r2

Topic: Physics, Thermal Properties of Matter, NEET
Assuming the sun to have a spherical outer surface of radius $r$, radiating like a black body at temperature $t^{\circ} \mathrm{C}$, the power received by a unit surface, (normal to the incident rays) at a distance $R$ from the centre of the sun is:
where $\sigma$ is the Stefan's constant

Options:
A $\frac{r^2 \sigma(t+273)^4}{4 \pi R^2}$
B $\frac{16 \pi^2 r^2 \sigma t^4}{R^2}$
C $\frac{r^2 \sigma(t+273)^4}{R^2}$
D $\frac{4 \pi r^2 \sigma t^4}{R^2}$

The correct answer is:
$\frac{r^2 \sigma(t+273)^4}{R^2}$

Solution:
$\begin{aligned}
\text { Solar constant } & =\frac{\sigma\left(4 \pi r^2\right) T^4}{\left(4 \pi R^2\right)} \\
& =\frac{\sigma r^2(t+273)^4}{R^2}
\end{aligned}$

Topic: Physics, Thermal Properties of Matter, NEET, NEET 2007
Assuming the water vapour to be a perfect gas, What is the internal energy change when 1 mol of water at 100°C and 1 bar pressure is converted to ice at 0°C? (Given: the enthalpy of fusion of ice is 6.00 kJ mol-1and heat capacity of water is 4.2 J/g°C)

Options:
A -15.48 kJ mol-1
B -13.56 kJ mol-1
C -11.23 kJ mol-1
D -17.56 kJ mol-1

The correct answer is:
-13.56 kJ mol-1

Solution:
Correct Option is : (B)
-13.56 kJ mol-1

Topic: Chemistry, Thermodynamics (C), NEET