datavorous/entrance-exam-dataset huggingface dataset:
The solubility product of a sparingly soluble salt $\mathrm{AX}_2$ is $3.2 \times 10^{-11}$. Its solubility (in moles/litre) is:

Options:
A $5.6 \times 10^{-6}$
B $3.1 \times 10^{-4}$
C $2 \times 10^{-4}$
D $4 \times 10^{-4}$

The correct answer is:
$2 \times 10^{-4}$

Solution:
$$
\begin{aligned}
& \mathrm{K}_{s p}= 3.2 \times 10^{-11} \\
& \mathrm{AX}_2 \rightleftharpoons \mathrm{A}^{2+}+2 \mathrm{X}^{-} \\
& \mathrm{S} \quad 2 \mathrm{~S} \\
& \mathrm{~K}_{s p}= \mathrm{S} \times(2 \mathrm{~S})^2=4 \mathrm{~S}^3 ; \\
&= 3.2 \times 10^{-11}=4 \mathrm{~S}^3
\end{aligned}
$$
or, $\quad \mathrm{S}^3=0.8 \times 10^{-11}=8 \times 10^{-12}$
$$
\therefore \quad \mathrm{S}=2 \times 10^{-4} \text {. }
$$
Related Theory
The solubility of a substance in a solvent is the total amount of the solute that can be dissolved in the solvent at equilibrium. On the other hand, the solubility product constant is an equilibrium constant that provides insight into the equilibrium between the solid solute and its constituent ions that are dissociated across the solution.

Topic: Chemistry, Ionic Equilibrium, NEET, NEET 2004
The solubility product of AgCl is 1.8×10-10 . Precipitation of AgCl will occur by mixing which of the following solutions are mixed in equal volumes?

Options:
A 10-8MAg+ and 10-8MCl- ions
B 10-3MAg+ and 10-3MCl- ions
C 10-6MAg+ and 10-6MCl- ions
D 10-10MAg+ and 10-80MCl- ions

The correct answer is:
10-3MAg+ and 10-3MCl- ions

Solution:
For precipitation, ionic product > solubility products. In all other options, ionic product is less than solubility product.
10-3MAg+×10-3MCl->Ksp(1.8×10-10)

Topic: Chemistry, Ionic Equilibrium, NEET
The solubility product of $\mathrm{Agl}$ at $25^{\circ} \mathrm{C}$ is $1.0 \times 10^{-16} \mathrm{~mol}^2 \mathrm{~L}^{-2}$. The solubility of $\mathrm{Agl}$ is $10^{-4} \mathrm{~N}$ solution of $\mathrm{KI}$ at $25^{\circ} \mathrm{C}$ is approximately (in $\mathrm{mol} \mathrm{L}^{\mathrm{1}}$ )

Options:
A $1.0 \times 10^{-16}$
B $1.0 \times 10^{-12}$
C $1.0 \times 10^{-10}$
D $1.0 \times 10^{-8}$

The correct answer is:
$1.0 \times 10^{-12}$

Solution:
$\mathrm{Agl} \rightleftharpoons \mathrm{Ag}^{+}+1^{-}$
$1.1 \times 10^{-16}=s^2$
Solubility of $\mathrm{Ag}^{-}=1.0 \times 10^{-8}$
Solubllity of $\mathrm{Agl}$ in KI solution:
$\begin{aligned}
& =1.0 \times 10^{-8} \times 10^{-4} \\
& =1.0 \times 10^{-12} \mathrm{~mol} \mathrm{~L}^{-1}
\end{aligned}$

Topic: Chemistry, Ionic Equilibrium, NEET, NEET 2003
The solubility product of Al (OH)3is 2.7 × 10–11. Calculate the pH of this solution. (Atomic mass of Al = 27 u).

Options:
A 10.33
B 13.39
C 12.36
D 11.47

The correct answer is:
11.47

Solution:
Correct Option is : (D)
11.47

Topic: Chemistry, Ionic Equilibrium, NEET
The solubility product of Cr(OH)3 at 298 K is 6.0×10-31 . The concentration of hydroxide ions in a saturated solution of Cr(OH)3 will be

Options:
A (18×10-31)1/4
B (4.86×10-29)1/4
C (18×10-31)1/2
D (2.22×10-31)1/4

The correct answer is:
(18×10-31)1/4

Solution:
CrOH3⇌Cr3+s+3OH−3s
6×10-31=S×(3S)3
6×10-31=27S4
S=627×10-311/4
[OH-]=3S=3627×10-311/4=(18×10-31)1/4M

Topic: Chemistry, Ionic Equilibrium, NEET
The solubility product of different sparingly soluble salts are
1. XY=4×10-20
2. X2Y=3.2×10-11
3. XY3=2.7×10-31
The increasing order of solubility is

Options:
A 1, 3, 2
B 2, 1, 3
C 1, 2, 3
D 3, 1, 2

The correct answer is:
1, 3, 2

Solution:
S(XY)=Ksp=4×10-20=2×10-10
S(X2Y)=Ksp41/3=3.2×10-1141/3=2×10-4
S(X3Y)=Ksp271/4=2.7×10-31271/4=10-8
Hence, the solubility order is XY<X3Y<X2Y .

Topic: Chemistry, Ionic Equilibrium, NEET
The solubility products of Al(OH)3 and Zn(OH)2 are 8.5×10-23 and 1.8×10-14 respectively. If NH4OH is added to a solution containing Al3+ and Zn2+ ions, then substance precipitated first is:

Options:
A Al(OH)3
B Zn(OH)2
C Both together
D None at all

The correct answer is:
Al(OH)3

Solution:
ppt occurs when ionic product is greater than solubility product. Solubility of Al(OH)3 is lesser than Zn(OH)2

Topic: Chemistry, Ionic Equilibrium, NEET
The solubility (S) of a solute in water varies with temperature as given by S=Ae-ΔH/RT,ΔH being the enthalpy of solution. For a given solute, variation of lnS with temperature is as shown in figure. The solute is expected to be

Options:
A CaO
B MgSO4
C CuSO4
D CuSO4.5H2O

The correct answer is:
CuSO4.5H2O

Solution:
lnS = lnA− ΔH RT
Slope =  −ΔH RT
lnS vs  1 T graph with negative slope.
So, ΔH>0
Salts with water of crystallisation.
i.e., CuSO4.5H2O .

Topic: Chemistry, Ionic Equilibrium, NEET
The source of complementary RNA required for RNA silencing is

Options:
A infection by a virus having DNA genome
B infection by a viriod having RNA genome
C transposons which have copy and paste mechanism of transfer
D transposons which have cut and paste mechanism of transfer

The correct answer is:
transposons which have copy and paste mechanism of transfer

Solution:
The process of RNAi involves silencing of a specific mRNA due to a complementary ssRNA molecule that binds to mRNA and prevents the translation by forming dsRNA(silencing). The consequence was that the host became inhospitable for the parasite to survive and thus the host is protected. The complementary RNA could be obtained from an infecting virus having RNA based genome or from transposons which can replicate using an RNA intermediate. Transposons are sequences of nucleic acids which can change position within the genome, hence, also called mobile genetic elements.

Topic: Biology, Biotechnology and Its Applications, NEET
The source of cyclosporin-A is

Options:
A Aspergillus niger
B Trichoderma polysporum
C Monascus purpureus
D Candida lipolytica

The correct answer is:
Trichoderma polysporum

Solution:
The bioactive molecule, cyclosporin A, that is used as an
immunosuppressive agent in organ-transplant patients is produced by the fungus Trichoderma polysporum.

Topic: Biology, Microbes in Human Welfare, NEET
The source of renin in the human kidney is

Options:
A Macula densa
B Juxta-glomerular cells
C Interstitial cells
D Cells of ducts of Bellini

The correct answer is:
Juxta-glomerular cells

Solution:
JGA (Juxta-glomerular Apparatus): JGA works via Renin-Angiotensin mechanism which works in the following manner:
A. Fall in glomerular blood flow/glomerular blood pressure/GFR â Activation of the JG cells â Release of Renin in blood.
B. Angiotensinogen ââReninâ Angiotensin I â Angiotensin II.
C. Angiotensin II performs 2 functions:
(i) Angiotensin II is a powerful vasoconstrictor â Vasoconstriction â Glomerular blood pressure increases â GFR increases.
(ii) Angiotensin II activates the adrenal cortex â Release of Aldosterone â Reabsorption of Na+ and water from the distal parts of the tubule â Increase in blood pressure â GFR increases.

Topic: Biology, Excretory Products and their Elimination, NEET
The source of the enzyme Urease is

Options:
A Soyabean
B Yeast
C Malt
D Stomach

The correct answer is:
Soyabean

Solution:
Correct Option is : 1
Soyabean

Topic: Chemistry, Surface Chemistry, NEET
The space within the coiled portion of the membranous labyrinth is called ______________, which is filled with ____________.

Options:
A scala vestibuli; perilymph
B scala tympani; perilymph
C scala vestibuli; endolymph
D scala media; endolymph

The correct answer is:
scala media; endolymph

Solution:
The coiled portion of the labyrinth is called cochlea. The membranes constituting cochlea, the reissnerâs and basilar, divide the surounding perilymph filled bony labyrinth into an upper scala vestibuli and a lower scala tympani. The space within cochlea called scala media is filled with endolymph.

Topic: Biology, Neural Control and Coordination, NEET
The specialised epithelial cells called podocytes are

Options:
A the squamous epithelial cells of glomerulus of nephron
B the cuboidal epithelial cells of glomerulus of nephron
C the cuboidal epithelial cells of Bowman's capsule of nephron
D the squamous epithelial cells of Bowman's capsule of nephron

The correct answer is:
the squamous epithelial cells of Bowman's capsule of nephron

Solution:
The specialised squamous epithelial cells of the Bowman's capsule of nephron are called podocytes. These cells are arranged in an intricate manner so as to leave minute space called filtration slits or slit pores, through which ultrafiltration occurs.

Topic: Biology, Excretory Products and their Elimination, NEET
The species Ar, K+ and Ca2+ contain the same number of electrons. In which order do their radii increase?

Options:
A Ar<K+<Ca2+
B Ca2+<Ar<K+
C Ca2+<K+<Ar
D K+<Ar<Ca2+

The correct answer is:
Ca2+<K+<Ar

Solution:
For isoelectronic species as ze ratio increases ionic size decreases.
(Total no. of electrons) = 18
For Arze=1818
K+ze=1918
Ca2+ze=2018
i.e. Ca2+<K+<Ar

Topic: Chemistry, Classification of Elements and Periodicity in Properties, NEET, NEET 2015 (Phase 1)
The species Ar, K+ and Ca2+ contain the same number of electrons. In which order do their radii increase?

Options:
A Ar<K+<Ca2+
B Ca2+<K+<Ar
C K+<Ar<Ca2+
D Ca2+<Ar<K+

The correct answer is:
Ca2+<K+<Ar

Solution:
In isoelectronic species atomic radius â1Zeffâ1charge on cation
M >  M + > M 2+
Hence, increasing order of radius is Ca2+<K+<Ar .

Topic: Chemistry, Classification of Elements and Periodicity in Properties, NEET
The species composition that invades a barren area and drives the succession is called

Options:
A a climax community
B a pioneer community
C the keystone species
D the standing crop

The correct answer is:
a pioneer community

Solution:
Gradual predictable change in species composition of an area is called as succession. The community which starts the process of succession in bare area is called as pioneer community and the community which at the end becomes stabilized is called as climax community.

Topic: Biology, Ecosystem, NEET
The species confined to a particular region and not found elsewhere termed as:

Options:
A Alien
B Endemic
C Rare
D Keystone

The correct answer is:
Endemic

Solution:
New species entering a geographical region are called exotic or alien or non-native species.

The species confined to a particular region and not found elsewhere is termed as endemic.

Keystone species are the one that drive major ecosystem functions.

Topic: Biology, Organisms and Populations, NEET, NEET 2015 (Phase 2)
The species having bond angles of 120° is

Options:
A PH3
B ClF3
C NCl3
D BCl3

The correct answer is:
BCl3

Solution:
The hybridisation is sp2.and for this hybridisation shape is trigonal planar in which bond angle is 120°.

Topic: Chemistry, Chemical Bonding and Molecular Structure, NEET, NEET 2017
The species, having bond angles of 120° is

Options:
A CIF3
B NCl3
C BCl3
D PH3

The correct answer is:
BCl3

Solution:
As BCl3 is planar molecule so have 120°

Topic: Chemistry, Chemical Bonding and Molecular Structure, NEET
The species having tetrahedral shape is

Options:
A [PdCl4]2-
B [Ni(CN)4]2-
C [Pd(CN)4]2-
D [NiCl4]2-

The correct answer is:
[NiCl4]2-

Solution:
Here [NiCl4]2- is tetrahedral as Ni2+ has sp3 hybridisation here. Rest other are square planar complexes with dsp2 hybridisation.

Topic: Chemistry, Coordination Compounds, NEET
The species: \(\mathrm{H}_2 \mathrm{O}, \mathrm{HCO}_3^{-}, \mathrm{HSO}_4^{-}\)and \(\mathrm{NH}_3\) can act both as Brönsted acids and bases. For each case give the corresponding conjugate acid and base.

Options:
A \(\mathrm{H}_2 \mathrm{O} / \mathrm{H}_3 \mathrm{O}^{+}, \mathrm{HCO}_3^{-} / \mathrm{H}_2 \mathrm{CO}_3, \mathrm{HSO}_4^{-} / \mathrm{H}_2 \mathrm{SO}_4, \mathrm{NH}_3 / \mathrm{NH}_4^{+}\)
B \(\mathrm{H}_2 \mathrm{O} / \mathrm{H}_3 \mathrm{O}^{+}, \mathrm{HCO}_3^{-} / \mathrm{HCOOH}, \mathrm{HSO}_4^{-} / \mathrm{HSOH}, \mathrm{NH}_3 / \mathrm{NH}_4^{+}\)
C \(\mathrm{H}_2 \mathrm{O} / \mathrm{H}_3 \mathrm{O}^{+}, \mathrm{HCO}_3^{-} / \mathrm{HCOO}^{-}, \mathrm{HSO}_4^{-} / \mathrm{HSO}_3^{-}, \mathrm{NH}_3 / \mathrm{NH}_4^{+}\)
D \(\mathrm{H}_2 \mathrm{O} / \mathrm{H}_3 \mathrm{O}^{+}, \mathrm{HCO}_3^{-} / \mathrm{HCOOH}_2^{+}, \mathrm{HSO}_4^{-} / \mathrm{HSO}_3^{-}, \mathrm{NH}_3 / \mathrm{NH}_4^{+}\)

The correct answer is:
\(\mathrm{H}_2 \mathrm{O} / \mathrm{H}_3 \mathrm{O}^{+}, \mathrm{HCO}_3^{-} / \mathrm{H}_2 \mathrm{CO}_3, \mathrm{HSO}_4^{-} / \mathrm{H}_2 \mathrm{SO}_4, \mathrm{NH}_3 / \mathrm{NH}_4^{+}\)

Solution:
Correct Option is : (A)
\(\mathrm{H}_2 \mathrm{O} / \mathrm{H}_3 \mathrm{O}^{+}, \mathrm{HCO}_3^{-} / \mathrm{H}_2 \mathrm{CO}_3, \mathrm{HSO}_4^{-} / \mathrm{H}_2 \mathrm{SO}_4, \mathrm{NH}_3 / \mathrm{NH}_4^{+}\)

Topic: Chemistry, Ionic Equilibrium, NEET
The species present in solution when CO2 is dissolved in water are

Options:
A CO2,H2CO3,HCO3-,CO32-
B H2CO3,CO32-
C CO32-,HCO3-
D CO2,H2CO3

The correct answer is:
CO2,H2CO3,HCO3-,CO32-

Solution:
CO2+H2O⇌H2CO3⇌H++HCO3-⇌H++CO32-

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
The species that come to appear in bare area are called :

Options:
A Pioneer species
B Invasive species
C Competitive species
D Species of seral community

The correct answer is:
Pioneer species

Solution:
During process of succession, the species which occupy bare are first time is called Pioneer species. It is the species with least adaptation and highest environmental resistance.

Topic: Biology, Organisms and Populations, NEET, NEET 2022 (Phase 2)
The species that invade a bare are to start the process of succession is called

Options:
A Climax Community
B Pioneer community
C Ecological species
D Standing crop

The correct answer is:
Pioneer community

Solution:
Gradual predictable change in species composition of an area is called as succession. The community which starts the process of succession in bare area is called as pioneer community and the community which at the end becomes stabilized is called as climax community.

Topic: Biology, Ecosystem, NEET
The species which acts as electrophile in the bromination of benzene is

Options:
A Br2
B Br-
C Br+
D Br*

The correct answer is:
Br+

Solution:
In the bromination of benzene: Br+ is the electrophile.

Topic: Chemistry, Haloalkanes and Haloarenes, NEET
The species which undergo disproportionation in alkaline medium is/are

Options:
A Cl2
B MnO4-
C NO2
D Both A and C

The correct answer is:
Both A and C

Solution:
The species which undergo disproportionation in alkaline medium are Cl2 and NO2
Cl2(0)+2NaOH→NaCl(-)+NaOCl(+1)+H2O
NO2(+4)+2NaOH→NaNO2(+3)+NaNO3(+5)+H2O

Topic: Chemistry, Redox Reactions, NEET
The species–area relationship represented by the equation log S = log C + Z log A is graphically seen as

Options:
A rectangular hyperbola with Z as its slope
B straight line with Z as its slope
C rectangular hyperbola with C as its slope
D straight line with C as its slope

The correct answer is:
straight line with Z as its slope

Solution:
On a logarithmic scale, the species area relationship is a straight line described by the equation log S = log C + Z log A,
where S= Species richness, A= Area, Z = slope of the line (regression coefficient) and C = Y-intercept. Ecologists have discovered that the value of Z lies in the range of 0.1 to 0.2, regardless of the taxonomic group or the region.

Topic: Biology, Biodiversity and its Conservation, NEET
The specific conductance of a 0.1 N KCl solution at 25°C is 0.015 ohm-1cm-1 . The resistance of the cell containing the solution at the same temperature was found to be 60 Ω .The cell constant (in cm-1) will be

Options:
A 0.9
B 4×103
C 2.5×10-4
D 1.11

The correct answer is:
0.9

Solution:
Cell constant = k×R
=0.015×60=0.9

Topic: Chemistry, Electrochemistry, NEET
The specific conductance of a 0.5 N solution of an electrolyte at 25°C is 0.00045 Scm-1 . The equivalent conductance of this electrolyte at infinite dilution is 300 S cm2eq-1 . The degree of dissociation of the electrolyte is

Options:
A 0.66
B 0.03
C 0.003
D 0.3

The correct answer is:
0.003

Solution:
Λv=K×1000CN=0.00045×10000.5
=0.9Scm2eq-1
α=ΛvΛ∞=0.9300=31000=0.003

Topic: Chemistry, Electrochemistry, NEET
The specific DNA sequence in which EcoRI cuts is

Options:
A GATTCG
B GAATTC
C GTTCAA
D TTCCAA

The correct answer is:
GAATTC

Solution:
EcoRI identifies a specific palindromic sequence GAATTC and cuts at specific site within the sequence making staggered cut.

Topic: Biology, Biotechnology - Principles and Processes, NEET
The specific DNA sequence recognised by EcoRI is

Options:
A 3' GAATTC 5'
B 5' GAATTC 3'
C 5' GTTAAC 3'
D 3' GTTAAC 5'

The correct answer is:
5' GAATTC 3'

Solution:
EcoRI recognizes the sequence 5' GAATTC 3' in double-stranded DNA. This recognition sequence is a palindrome with a two-fold axis of symmetry because reading from 5' to 3' on either strand of the helix gives the same sequence.

Topic: Biology, Biotechnology - Principles and Processes, NEET
The specific heat of an ideal gas varies with temperature T as

Options:
A T1
B T2
C T-2
D T0

The correct answer is:
T0

Solution:
Specific heat of an ideal gas does not depend upon temperature

Topic: Physics, Kinetic Theory of Gases, NEET
The specific heats CP and CV, of a diatomic gas A are 29 J mol-1K-1 and 22 J mol-1K-1 respectively. Another diatomic gas B, has the corresponding values as 30 J mol-1K-1 and 21 J mol-1K-1 respectively. Which among the following is correct?

Options:
A

A has one vibrational degree of freedom and B has two vibrational degrees of freedom

B

A has one vibrational degree of freedom and B has zero vibrational degree of freedom

C

A and B both have one vibrational degree of freedom

D

A and B both have two vibrational degrees of freedom

The correct answer is:

A has one vibrational degree of freedom and B has zero vibrational degree of freedom

Solution:
If f is the degree of freedom of a gas molecule, then

CPCV=f+2fCPCVA=2922=fA+2fA⇒fA=6CPCVB=3021=fA+2fA⇒fB=5

So A has one vibrational degree of freedom and B has none

Topic: Physics, Thermal Properties of Matter, NEET
The specific palindromic sequence which is recognized by EcoRl is

Options:
A 5' - GGAACC - 3'
3' - CCTTGG - 5'
B 5' - CTTAAG - 3'
3' - GAATTC - 5'
C 5' - GGATCC - 3'
3' - CCTAGG - 5'
D 5' - GAATTC - 3'
3' - CTTAAG - 5'

The correct answer is:
5' - GAATTC - 3'
3' - CTTAAG - 5'

Solution:
Palindrome in DNA is a sequence of base pairs that reads the same on the two strands when the orientation of reading is kept the same. These sequences may range from 4-8 nucleotides in length. For example, the restriction site for EcoRI is between G and A residues in the palindromic sequence given below.

↓5'- GAATTC -3'3'- CTTAAG -5' ↑

Topic: Biology, Biotechnology - Principles and Processes, NEET, NEET 2020 (Phase 1)
The specific property attributed to gibberellins is

Options:
A Shortening of genetically tall plants
B Elongation of genetically dwarf plant
C Promotion of rooting
D Yellowing of young leaves

The correct answer is:
Elongation of genetically dwarf plant

Solution:
Gibberellins are weakly acidic hormones having gibbane ring structure which cause cell elongation of intact plants in general and increased internodal length of genetically dwarfed plants (i.e., corn, pea) in particular.

Topic: Biology, Plant - Growth and Development, NEET
The specific rotation of a pure enantiomer is +16 o . The observed rotation, if it is isolated from a reaction with 25% racemisation and 75% inversion is

Options:
A + 12 o
B − 12 o
C 4 o
D − 4 o

The correct answer is:
− 12 o

Solution:
Specific rotation of inverted isomer =â 16 o
Angle of rotation =(Specific rotation of inverted isomer)Ã(Fraction of inversion)
=−16× 75 100 =− 12 o

Topic: Chemistry, General Organic Chemistry, NEET
The spectral emissive power E Î» for a body at temperature T1 is plotted against the wavelength (see figure) and area under the curve is found to be A. At a different temperature T2 the area is found to be 9A. Then Î» 1 / Î» 2 =

Options:
A 3
B 1 3
C 1 3
D 3

The correct answer is:
3

Solution:
E1E2=19=T1T24
λ1T1=λ2T2⇒T1T2=λ2λ1
19=λ2λ14⇒λ2λ1=13
λ1λ2=3

Topic: Physics, Thermal Properties of Matter, NEET
The spectral energy distribution of the Sun has a maximum at 4753 Aâ. If the temperature of the Sun is 6050 K, the temperature of a star for which this maximum is at 9506 Aâ is

Options:
A 3025 K

B 2785 K

C 3240 K

D 4015 K

The correct answer is:
3025 K

Solution:
Let T and T' be the temperatures of the sun and the star respectively.
If λmax and λmax' are the corresponding wavelengths of maximum emission, then
T ′ = λ max λ max ′ × T = 4753 9506 × 6050 = 3025 K

Topic: Physics, Thermal Properties of Matter, NEET
The spectral energy distribution of the Sun (temperature = 6050 K ) has a maximum at 4753 â« . The temperature of a star for which this maximum is at 9506 â« is

Options:
A 6050 K
B 3025 K
C 12100 K
D 24200 K

The correct answer is:
3025 K

Solution:
Let For Sun Î»m1= 4753 â« and T1= 6050 K.
For Star Î»m2= 9506 AÂ° and T2= ?
From Wien's law
Î»maxT = b where b is Wien's constant.
Î»m2T2=Î»m1T1
T2=Î»m1Î»m2Ã T1
T2=47539506Ã6050=3025 K
Temperature of Star =3025 K .

Topic: Physics, Thermal Properties of Matter, NEET
The spectral series which corresponds to the electronic transition from the levels $n_2=5,6, \ldots$ to the level $n_1=4$ is

Options:
A Pfund series
B Brackett series
C Lyman series
D Balmer series

The correct answer is:
Brackett series

Solution:
The spectral series which corresponds to the electronic transition from the levels $n_2=5,6, \ldots$ to $n_1=4$ is Brackett series.

Topic: Physics, Atomic Physics, NEET, NEET 2024 (Re-NEET)
The spectrum of an oil flame is an example for

Options:
A Line emission spectrum
B Continuous emission spectrum
C Line absorption spectrum
D Band emission spectrum

The correct answer is:
Continuous emission spectrum

Solution:
Since spectrum of an oil flame consists of continuously varying wavelength in a definite wavelength range, it is an example for continuous emission spectrum.

Topic: Physics, Atomic Physics, NEET
The speed of a boat in still water is 15 km h-1 and the rate of current is 3 km h-1. The distance travelled downstream in 12 minutes is

Options:
A 1.2 km
B 1.8 km
C 2.4 km
D 3.6 km

The correct answer is:
3.6 km

Solution:
Speed downstream =(15 + 3) kmph=18 kmph
Distance travelled =18×1260 km=3.6 km

Topic: Physics, Motion In One Dimension, NEET
The speed of a body moving with uniform acceleration is u. This speed is doubled while covering a distance S. When it covers an additional distance S, its speed would become

Options:
A 3u
B 5u
C 11u
D 7u

The correct answer is:
7u

Solution:
As v2=u2+2as⇒2u2=u2+2as⇒2as=3u2
Now, after covering an additional distance s, if velocity becomes v, then,
v2=u2+2a2s=u2+4as=u2+6u2=7u2
∴ v=7u

Topic: Physics, Motion In One Dimension, NEET
The speed of a particle moving in a circle of radius r=2 m varies with time t as v=t2 where t is in second and v is in m s-1. Find the net acceleration at t=2 s.

Options:
A 80 m s-2
B 90 m s-2
C 120 m s-2
D 70 m s-2

The correct answer is:
80 m s-2

Solution:
The linear speed of the particle at t=2 s is
v=22=4 m s-1
∴ Radial acceleration ar=v2r=422=8 m s-2
The tangential acceleration is at=dvdt=2t
∴ Tangential acceleration at t=2 s is
at=22=4 m s-2
∴ Net acceleration of at t=2 s is
a=ar2+at2=82+42
Or a=80 m s-2

Topic: Physics, Laws of Motion, NEET
The speed of a swimmer in still water is 20 m s-1. The speed of river water is 10 m s-1 and is flowing due east. If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which he should make his strokes with respect to the north is given by

Options:
A 30° west
B 0°
C 60° west
D 45° west

The correct answer is:
30° west

Solution:
For reaching just apposite bank of the river the net velocity at the river should be zero that means

vsinθ = velocity of river

sinθ=velocity of rivervelocity of swimmer

sinθ=1020=12
θ=30°
30° west of north

Topic: Physics, Motion In Two Dimensions, NEET, NEET 2019 (All India)
The speed of a wave in a string is 20 m s-1 and frequency is 50 Hz . The phase difference between two points on the string 10 cm apart will be

Options:
A π2
B π
C 3π2
D 2π

The correct answer is:
π2

Solution:
Δϕ=2πλΔx=2πv.n.Δx
Δϕ=2π20×50×10100
Δϕ=π2

Topic: Physics, Waves and Sound, NEET