datavorous/entrance-exam-dataset huggingface dataset:
Which one of the following compounds will be most readily dehydrated?

Options:
A

B

C

D

The correct answer is:

Solution:
Dehydration of alcohols involve formation of carbocation intermediate. More the stability of carbocation, higher is the ease of dehydration. The order of stability of carbocation, given by the given compounds, is
Thus, compound given in OPTION (c) readily undergoes dehydration.

Topic: Chemistry, Alcohols Phenols and Ethers, JEE Main
Which one of the following compounds will give orange precipitate when treated with 2, 4 -dinitrophenyl hydrazine ?

Options:
A
B
C
D

The correct answer is:

Solution:
Explanation ⇒2-4-D.N.P test is used for carbonyl compound (aldehyde & ketone)

Topic: Chemistry, Alcohols Phenols and Ethers, JEE Main, JEE Main 2021 (27 Jul Shift 1)
Which one of the following compounds will react with methyl magnesium iodide?

Options:
A $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}$
B
C
D

The correct answer is:

Solution:
due to the presence of acidic hydrogen (hydrogen attached to triply bonded carbon atom) terminal alkyne $(d)$ will react with methyl magnesium bromide.

Topic: Chemistry, Hydrocarbons, JEE Main
Which one of the following conditions in humans is correctly matched with its chromosomal abnormality/ linkage?

Options:
A Down syndrome - 44 autosomes $+\mathrm{XO}$
B Klinefelter syndrome - 44 autosomes + XXY
C Colour blindness - Y-linked
D Erythroblastosis foetalis - X-linked

The correct answer is:
Klinefelter syndrome - 44 autosomes + XXY

Solution:
Downs syndrome $-45+\mathrm{XX}$ or $45+\mathrm{XY}$

Topic: Biology, Principles of Inheritance and Variation, NEET, NEET 2008 (Mains)
Which one of the following conditions of the zygotic cell would lead to the birth of a normal human female child?

Options:
A Two X-chromosomes
B Only one Y-chromosome
C Only one X-chromosome
D One X and one Y-chromosome

The correct answer is:
Two X-chromosomes

Solution:
The sex determining mechanism in case of humans is XY type. Sperms are of two types, one containing X-chromosome and another containing Y-chromosome.
The ovum is of one type only, ie, contain X chromosome. The fertilization of ovum with Y-chromosome carrying sperm results into a male offspring.

Topic: Biology, Principles of Inheritance and Variation, NEET, NEET 2011 (Mains)
Which one of the following conditions though harmful in itself, is also potential saviour from a mosquito borne infectious disease?

Options:
A thalassaemia
B sickle cell anaemia
C pernicious anaemia
D leukaemia

The correct answer is:
sickle cell anaemia

Solution:
Sickle cell anaemia is a genetic disorder caused by a variant form of haemoglobin in red blood cells. Individual homozygous for this disorder die at an early stage. In heterozygotes also the redblood cells with variant form of haemoglobin become sickle-shaped and were unable to bind oxygen efficiently. Even then the natural selection could not eliminate this abnormal allele from the population. This variant is often found in tropical Africa where malaria is common. Since sickle-shaped RBC effectively kills the malaria parasite, the individuals heterozygous for this variant are able to cope with malaria infections much better than normal persons. The natural selection thus maintains this variant form of haemoglobin along with the normal haemoglobin in malaria prone areas.
Pernicous anaemia is caused due to deficiency of vitamin $\mathrm{B}_{12}$. Leukemia is cancer of the body's blood-forming tissues, including the bone marrow and the lymphatic system. Thalassemia is caused by mutations in the DNA of cells that make hemoglobin.

Topic: Biology, Principles of Inheritance and Variation, NEET, NEET 2003
Which one of the following conformation of cyclohexane is chiral?

Options:
A
Twist boat

B
Rigid

C
Chair

D
Boat

The correct answer is:
Twist boat

Solution:
Twisted boat is chiral as it does not have plane of symmetry.
Hence, (A) is correct.

Topic: Chemistry, General Organic Chemistry, JEE Main, JEE Main 2007
Which one of the following constitutes a group of the isoelectronic species?

Options:
A
$\mathrm{C}_2^{2-}, \mathrm{O}_2^{-}, \mathrm{CO}, \mathrm{NO}$

B
$\mathrm{NO}^{+}, \mathrm{C}_2^{2-}, \mathrm{CN}^{-}, \mathrm{N}_2$

C
$\mathrm{CN}^{-}, \mathrm{N}_2, \mathrm{O}_2^{2-}, \mathrm{C}_2^{2-}$

D
$\mathrm{N}_2, \mathrm{O}_2^{-}, \mathrm{NO}^{+}, \mathrm{CO}$

The correct answer is:
$\mathrm{NO}^{+}, \mathrm{C}_2^{2-}, \mathrm{CN}^{-}, \mathrm{N}_2$

Solution:
$\mathrm{NO}^{+}, \mathrm{C}_2^{2-}, \mathrm{CN}^{-}$and $\mathrm{N}_2$ all have fourteen electrons.

Topic: Chemistry, Structure of Atom, JEE Main, JEE Main 2008
Which one of the following coordination entity is chiral?

Options:
A trans $-\left[\mathrm{CrCl}_{2}(\mathrm{ox})_{2}\right]^{3-}$
B cis- $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{3}\right]^{+}$
C cis-[CrCl $\left.\mathrm{C}_{2}(\mathrm{ox})_{2}\right]^{3-}$
D trans- $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right]^{+}$

The correct answer is:
cis-[CrCl $\left.\mathrm{C}_{2}(\mathrm{ox})_{2}\right]^{3-}$

Solution:
Octahedral complex of general formula $\left[M(A A)_{2} a_{2}\right]^{n \pm}$ show optical isomerism. Trans form of $\left[M(A A)_{2} a_{2}\right]^{n \pm}$ does not show optical isomerism due to symmetry.
cis-[Co(NH$\left.\left.)_{3}\right)_{4} \mathrm{Cl}_{2}\right]^{+}$and trans- $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right]^{+}$do not show optical isomerism due to symmetry.

Topic: Chemistry, Coordination Compounds, JEE Main
Which one of the following correctly described the location of some body parts in the earthworm Pheretima?

Options:
A Two pairs of accessory glands in 16-18 segments
B Two pairs of testes in $10^{\text {th }}$ and $11^{\text {th }}$ segments.
C Four pairs of spermathecae in 4-7 segments
D One pair of ovaries attached at intersegmental septum of $14^{\text {th }}$ and 15 th segments.

The correct answer is:
Two pairs of testes in $10^{\text {th }}$ and $11^{\text {th }}$ segments.

Solution:
No Solution Available

Topic: Biology, Structural Organisation in Animals, NEET, NEET 2009 (Mains)
Which one of the following correctly represents the normal adult human dental formula?

Options:
A $\frac{3}{3}, \frac{1}{1}, \frac{3}{2}, \frac{1}{1}$
B $\frac{2}{2}, \frac{1}{1}, \frac{3}{2}, \frac{3}{3}$
C $\frac{2}{2}, \frac{1}{1}, \frac{2}{2}, \frac{3}{3}$
D $\frac{3}{3}, \frac{1}{1}, \frac{3}{3}, \frac{3}{3}$

The correct answer is:
$\frac{2}{2}, \frac{1}{1}, \frac{2}{2}, \frac{3}{3}$

Solution:
The number of each type of tooth varies from one species to another and the convetional way of describing them is by a 'dental formula'. The type of teeth are indicated by the first letter, and the number of teeth on one side of upper jaw is indicated over the number of same type of teeth on the lower jaw. Because the formula is for one side of the mouth, the total number of teeth is the total in the formula $\times 2$. The dental formula for human adult is as follows :
$$
\mathrm{I}-2 / 2, \mathrm{C}-1 / 1, \mathrm{Pm}-2 / 2, \mathrm{M}-3 / 3=16 \times 2=32
$$
where, $\mathrm{I}=$ Incisors, $\mathrm{C}=$ Canines, $\mathrm{Pm}=$ Premolar and $\mathrm{M}=$ Molars.

Topic: Biology, Digestion and Absorption, NEET, NEET 2011 (Mains)
Which one of the following correctly represents the order of stability of oxides, X2O; (X= halogen ) ?

Options:
A Cl>I>Br
B Br>Cl>I
C I>Cl>Br
D Br>I>Cl

The correct answer is:
I>Cl>Br

Solution:
lodine oxygen bond is stable due to the greater polarity of bond and stability of chlorine oxygen bond is due to multiple bond formation with orbital of chlorine atom. Now, Br is not having both characteristics. So, the stability order of oxide is given as I>Cl>Br.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), JEE Main, JEE Main 2021 (31 Aug Shift 2)
Which one of the following correctly represents the variation of electronegativity (EN) with atomic number $(Z)$ of group 13 elements?

Options:
A

B

C

D

The correct answer is:

Solution:
For group 13 elements, electronegativity decreases from B to Al. The decrease in electronegativity from $\mathrm{B}$ to $\mathrm{Al}$ is due to increased size of Al. The remaining three elements are more electro negative than $\mathrm{Al}$ and their electroonegativity increases from Ga to TI.
Thus, the correct order of electronegativity of group 13 elements are as follows.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, AP EAMCET, AP EAMCET 2014
Which one of the following correctly represents the variation of electronegativity (EN) with atomic number $(Z)$ of group 13 elements?

Options:
A

B

C

D

The correct answer is:

Solution:
For group 13 elements, electronegativity decreases from B to Al. The decrease in electronegativity from $\mathrm{B}$ to $\mathrm{Al}$ is due to increased size of Al. The remaining three elements are more electro negative than $\mathrm{Al}$ and their electroonegativity increases from Ga to TI.
Thus, the correct order of electronegativity of group 13 elements are as follows.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, JEE Main
Which one of the following correctly represents the variation of electronegativity (EN) with atomic number $(Z)$ of group 13 elements?

Options:
A

B

C

D

The correct answer is:

Solution:
For group 13 elements, electronegativity decreases from B to Al. The decrease in electronegativity from $\mathrm{B}$ to $\mathrm{Al}$ is due to increased size of Al. The remaining three elements are more electro negative than $\mathrm{Al}$ and their electroonegativity increases from Ga to TI.
Thus, the correct order of electronegativity of group 13 elements are as follows.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, TS EAMCET, TS EAMCET 2014
Which one of the following corresponds to a photon of highest energy?

Options:
A $\lambda=300 \mathrm{mm}$
B $v=3 \times 10^{4} \mathrm{s}^{-1}$
C $\bar{v}=30 \mathrm{cm}^{-1}$
D $\varepsilon=6.626 \times 10^{-27} \mathrm{J}$

The correct answer is:
$\lambda=300 \mathrm{mm}$

Solution:
$\because E=h v=\frac{h c}{\lambda}=h c \cdot \bar{v} \quad\left(\because \frac{1}{\lambda}=\bar{v}\right)$
where $E=$ energy of photon
$c=$ velocity of photon (-light)
$\lambda=$ wavelength of photon
$h=$ plank's constant.
$\therefore$ For $(\mathrm{a})$
$E=6.63 \times 10^{-34} \times 3 \times 10^{4} / 300 \times 10^{-9}$
$E=1.98 \times 10^{-25} \cdot \mathrm{J} / 300 \times 10^{-9}$
$\therefore \quad E=\frac{1.98 \times 10^{-2} \mathrm{J}}{300 \times 10^{-9} \mathrm{m}}$
$(a) \rightarrow E=6.6 \times 10^{-19} \mathrm{J}$
For (b) $E=h v=6.63 \times 10^{-34} \times 3 \times 10^{4}$
$(b) \rightarrow E=1.98 \times 10^{-35} \mathrm{J}$
For (c) $E=h c \times v$
$\because \frac{1}{3}$
$$
E=6.63 \times 10^{-4} \times 3 \times 10^{*} \times 30 \times 10^{2}
$$
(c) $\Rightarrow E=5.96 \times 10^{\circ}$
For $(d) d \rightarrow E=6.62 \times 10^{-27} J$
Hence, highest energy for photon is in (a).

Topic: Chemistry, Structure of Atom, JEE Main
Which one of the following crystals does not exhibit Frenkel defect

Options:
A $A g B r$
B $\mathrm{AgCl}$
C $\mathrm{KBr}$
D $\mathrm{ZnS}$

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

Solution:
$\mathrm{KBr}$ exhibits Schottky defect and not Frenkel defect.

Topic: Chemistry, Solid State, JEE Main
Which one of the following cyano complexes would exhibit the lowest value of paramagnetic behaviour?
(At. No. $\mathrm{Cr}=24, \mathrm{Mn}=25, \mathrm{Fe}=26, \mathrm{Co}=27$ )

Options:
A
$\left[\mathrm{Cr}(\mathrm{CN})_6\right]^{-3}$

B
$\left[\mathrm{Mn}(\mathrm{CN})_6\right]^{-3}$

C
$\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{-3}$

D
$\left[\mathrm{Co}(\mathrm{CN})_6\right]^{-3}$

The correct answer is:
$\left[\mathrm{Co}(\mathrm{CN})_6\right]^{-3}$

Solution:
No Solution Available

Topic: Chemistry, Coordination Compounds, JEE Main, JEE Main 2005
Which one of the following defects in the crystals lowers its density?

Options:
A Frenkel defect
B Schottky defect
C F-centres
D Interstitial defect

The correct answer is:
Schottky defect

Solution:
Schottky defects - This defect is due to vacancy at a cation site accompanied by vacancy at an anion site so that the electrical neutrality of the system is maintained. Due to this defect, density decreases.

Topic: Chemistry, Solid State, JEE Main
Which one of the following depletes ozone layer?

Options:
A
$\mathrm{CO}$

B
$\mathrm{NO}$ and freons

C
$\mathrm{SO}_2$

D
$\mathrm{CO}_2$

The correct answer is:
$\mathrm{NO}$ and freons

Solution:
NO and freons are responsible for ozone layer depletion.

Topic: Chemistry, Environmental Chemistry, JEE Main, JEE Main 2012 (26 May Online)
Which one of the following depresses brain activity and produces feelings of calmness, relaxation and drowsiness?

Options:
A Morphine
B Valium
C Amphetamines
D Hashish

The correct answer is:
Valium

Solution:
Valium is a benzodiazephine (sedative) that gives a feeling of relaxation, calmness or drowsiness in the body. Morphine is the main opium alkaloid that depresses respiratory centre and contributes to the fall in blood pressure. Amphetamines are synthetic drugs and are stimulant in nature. Hashish is a hallucinogen.

Topic: Biology, Human Health and Diseases, AIIMS, AIIMS 2009
Which one of the following diagrams represents the placentation in Dianthus?

Options:
A

B

C

D

The correct answer is:

Solution:
When the ovules are borne on central axis and septa are absent, as in Dianthus and Primerose, the placentation is called free-central.

Topic: Biology, Morphology of Flowering Plants, NEET, NEET 2011 (Mains)
Which one of the following does not correctly represent the correct order of the property indicated against it?

Options:
A $\mathrm{Ti} < \mathrm{V} < \mathrm{Cr} < \mathrm{Mn}$ : increasing number of oxidation states
B $\mathrm{Ti}^{3+} < \mathrm{V}^{3+} < \mathrm{Cr}^{3+} < \mathrm{Mn}^{3+}$ : increasing magnetic moment
C $\mathrm{Ti} < \mathrm{V} < \mathrm{Cr} < \mathrm{Mn}$ : increasing melting points
D $\mathrm{Ti} < \mathrm{V} < \mathrm{Mn} < \mathrm{Cr}$ : increasing second ionisation enthalpy

The correct answer is:
$\mathrm{Ti} < \mathrm{V} < \mathrm{Cr} < \mathrm{Mn}$ : increasing melting points

Solution:
$\therefore$ Order of oxidation states is
$$
\mathrm{Ti} < \mathrm{V} < \mathrm{Cr} < \mathrm{Mn}
$$
(b) $\because$ Magnetic moment, $\mu=\sqrt{n(n+2)}$ where, $n=$ no. of unpaired electrons
$\therefore$ Order of magnetic moment is
$$
\mathrm{Ti}^{3+} < \mathrm{V}^{3+} < \mathrm{Cr}^{3+} < \mathrm{Mn}^{3+}
$$
(c) In 3 -series melting point increases as we move from left to right. But Mn shows low melting point due to its complex formating nature. It is unable to form metallic and covalent bonds.
(d)
$\therefore$ Order of second ionisation enthalpy is
$$
\mathrm{Ti} < \mathrm{V} < \mathrm{Mn} < \mathrm{Cr}
$$

Topic: Chemistry, d and f Block Elements, NEET, NEET 2012 (Mains)
Which one of the following does not exhibit geometrical isomerism?

Options:
A Octahedral complex with formula $\left[M X_2 L_4\right]$
B Square planar complex with formula $\left[M X_2 L_2\right]$
C Tetrahedral complex with formula $[M A B X L]$
D Octahedral complex with formula $\left[M X_2(L-L)_2\right]$

The correct answer is:
Tetrahedral complex with formula $[M A B X L]$

Solution:
All the other three exhibit geometrical isomerism but tetrahedral complex does not.

Topic: Chemistry, Coordination Compounds, JEE Main
Which one of the following does not have a pyramidal shape?

Options:
A
$\left(\mathrm{CH}_3\right)_3 \mathrm{~N}$

B
$\left(\mathrm{SiH}_3\right)_3 \mathrm{~N}$

C
$\mathrm{P}\left(\mathrm{CH}_3\right)_3$

D
$\mathrm{P}\left(\mathrm{SiH}_3\right)_3$

The correct answer is:
$\left(\mathrm{SiH}_3\right)_3 \mathrm{~N}$

Solution:
In case of $\mathrm{N}\left(\mathrm{SiH}_3\right)_3 \mathrm{~N}$ atom is $s p^2$ hybridised, the lone pair is present in $2 p$ orbital and it is transferred to empty $d$ orbital of Si forming $d \pi-p \pi$ bond. Hence nitrogen with $s p^2$ hybridization has trigonal planar shape.

Topic: Chemistry, Chemical Bonding and Molecular Structure, JEE Main, JEE Main 2014 (11 Apr Online)
Which one of the following does not have a pyramidal shape ?

Options:
A P(CH3)3
B (CH3)3N
C P(SiH3)3
D (SiH3)3N

The correct answer is:
(SiH3)3N

Solution:
The Lone pair of electron available on N atom involved in p Ï - d Ï Bonding due to empty d-orbitals available on silicon atoms of salyl groups.
the central N-atom is sp2 hybridisied with Trigonal planar arrangement.

Topic: Chemistry, Chemical Bonding and Molecular Structure, JEE Main
Which one of the following does not represent Arrhenius equation

Options:
A $k=A e^{-E / R T}$
B $\log _e k=\log _e A-\frac{E}{R T}$
C $\log _{10} k=\log _{10} A-\frac{E}{2.303 R T}$
D $k=A E^{-R T}$

The correct answer is:
$k=A E^{-R T}$

Solution:
Its a Endothermic Reaction, So
\(\Delta \mathrm{H}=\left[\mathrm{E}_{\mathrm{a}(\mathrm{f})}\right]-\left[\mathrm{E}_{\mathrm{b}(\mathrm{f})}\right]\)
Given, \(\left[\mathrm{E}_{\mathrm{a}(\mathrm{f})}\right]=15 \mathrm{kcal} / \mathrm{mol}\) and \(\Delta \mathrm{H}=5 \mathrm{kcal} / \mathrm{mol}\)
\(\left[\mathrm{E}_{\mathrm{b}(\mathrm{f})}\right]=15-5=10 \mathrm{kcal} / \mathrm{mol}\)

Topic: Chemistry, Chemical Kinetics, JEE Main
Which one of the following does not undergo disproportionation reaction?

Options:
A $\mathrm{ClO}^{-}$
B $\mathrm{ClO}_3^{-}$
C $\mathrm{ClO}_2^{-}$
D $\mathrm{ClO}_4^{-}$

The correct answer is:
$\mathrm{ClO}_4^{-}$

Solution:
No solution. Refer to answer key.

Topic: Chemistry, Redox Reactions, JEE Main
Which one of the following electrolytes is used in Down's process of extracting sodium metal?

Options:
A $\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}$
B $\mathrm{NaCl}$
C $\mathrm{NaOH}+\mathrm{KCl}+\mathrm{KF}$
D $\mathrm{NaCl}+\mathrm{NaOH}$

The correct answer is:
$\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}$

Solution:
Sodium metal is manufactured by the electrolysis of fused sodium chloride mixed with $\mathrm{KCl}$ and $\mathrm{KF}$.
On electrolysis
At iron cathode.
$\mathrm{Na}^{+}+e^{-} \longrightarrow \mathrm{Na}(s)$ (metallic sodium)
At graphite anode
$2 \mathrm{Cl}^{-} \longrightarrow \mathrm{Cl}_2(g)+2 e^{-}$
$\mathrm{NaCl}$ melts at $800^{\circ} \mathrm{C}$. It is difficult to attain and maintain its melting point. So, $\mathrm{KCl}$ and $\mathrm{KF}$ are mixed to lower the melting point of $\mathrm{NaCl}$ to about $600^{\circ} \mathrm{C}$. $\mathrm{KCl}$ and $\mathrm{KF}$ are themselves not electrolysed under the voltage conditions used for sodium.

Topic: Chemistry, s Block Elements, AP EAMCET, AP EAMCET 2003
Which one of the following electrolytes is used in Down's process of extracting sodium metal?

Options:
A $\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}$
B $\mathrm{NaCl}$
C $\mathrm{NaOH}+\mathrm{KCl}+\mathrm{KF}$
D $\mathrm{NaCl}+\mathrm{NaOH}$

The correct answer is:
$\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}$

Solution:
Sodium metal is manufactured by the electrolysis of fused sodium chloride mixed with $\mathrm{KCl}$ and $\mathrm{KF}$.
On electrolysis
At iron cathode.
$\mathrm{Na}^{+}+e^{-} \longrightarrow \mathrm{Na}(s)$ (metallic sodium)
At graphite anode
$2 \mathrm{Cl}^{-} \longrightarrow \mathrm{Cl}_2(g)+2 e^{-}$
$\mathrm{NaCl}$ melts at $800^{\circ} \mathrm{C}$. It is difficult to attain and maintain its melting point. So, $\mathrm{KCl}$ and $\mathrm{KF}$ are mixed to lower the melting point of $\mathrm{NaCl}$ to about $600^{\circ} \mathrm{C}$. $\mathrm{KCl}$ and $\mathrm{KF}$ are themselves not electrolysed under the voltage conditions used for sodium.

Topic: Chemistry, s Block Elements, TS EAMCET, TS EAMCET 2003
Which one of the following electronic arrangements is absurd?

Options:
A $n=3, l=1, m=-1$
B $n=3, l=0, m=0$
C $n=2,l=0, m=-1$
D $n=2, l=1, m=0$

The correct answer is:
$n=2,l=0, m=-1$

Solution:
The three quantum numbers $n, l$ and $m$ that describe an orbital has integer values of 0,1,2,3 and so on.

The electronic arrangement of option (c) is absurd because
$$
\begin{array}{l}
n=2 \\
l=0 \\
m=0
\end{array}
$$
To sum up, where $n=2, l=0, m=0$ Hence, for $l=0,$ value of $m$ should be zero.

Topic: Chemistry, Structure of Atom, JEE Main
Which one of the following elemental forms is not present in the enamel of the teeth?

Options:
A Ca2+
B P3+
C F-
D P5+

The correct answer is:
P3+

Solution:
Calcium phosphate is the major component of hydroxyapatite crystal that form the inorganic portion of the teeth

Calcium phosphate is a mineral comprising calcium ion (Ca2+) and phosphate ion P+5. It is present in the crown area of the tooth and also in bones. It contain some F- ions too. But it does not contain P+3 ions.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), JEE Main, JEE Main 2022 (24 Jun Shift 1)
Which one of the following elements is unable to form MF63- ion?

Options:
A B
B Al
C Ga
D In

The correct answer is:
B

Solution:
MF63−
Boron belongs to 2nd period and it does not have vacant d-orbital.
It can form only 3 and 4 bond and cannot form 6 bond.

Topic: Chemistry, p Block Elements (Group 13 & 14), JEE Main
Which one of the following elements reacts with steam?

Options:
A C
B $\mathrm{Ge}$
C Si
D Sn

The correct answer is:
Sn

Solution:
C, Si and Ge do not react with water while Sn reacts with steam and forms $\mathrm{SnO}_2$ and $\mathrm{H}_2$.
$\mathrm{Sn}(\mathrm{s})+2 \mathrm{H}_2 \mathrm{O}(g) \stackrel{\Delta}{\longrightarrow} \mathrm{SnO}_2(g)+2 \mathrm{H}_2(g)$

Topic: Chemistry, p Block Elements (Group 13 & 14), JEE Main
Which one of the following elements, when present as an impurity in silicon makes it a p-type semiconductor?

Options:
A $\mathrm{As}$
B $\mathrm{P}$
C $\mathrm{In}$
D $\mathrm{Sb}$

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

Solution:
When silicon is doped with such an impurity valency of which is less than $4, p$-type semiconductor is obtained.
valency of As, P and Sb is +5 and of In is +3 .
Thus, In is the impurity which when added to $\mathrm{Si}$ gives $p$-type semiconductor.

Topic: Chemistry, p Block Elements (Group 13 & 14), JEE Main
Which one of the following elements will remain as liquid inside pure boiling water?

Options:
A Ga
B Br
C Li
D Cs

The correct answer is:
Ga

Solution:
Gallium (Ga) remains as liquid inside boiling water, and the other elements mentioned in options can react with water.

Bromine is a halogen that reacts readily with water to form hydrobromic acid and hypobromous acid, which can further react to form bromic acid. Lithium and Caesium are alkali metals that react violently with water, producing hydrogen gas and the corresponding metal hydroxide.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, JEE Main, JEE Main 2023 (06 Apr Shift 2)
Which one of the following equations does not correctly represent the first law of thermodynamics for the given processes involving an ideal gas? (Assume non- expansion work is zero)

Options:
A Isochoric process : ΔU=q
B Isochoric process : q= –w
C Cyclic process : q= –w
D Adiabatic process : ΔU=-w

The correct answer is:
Adiabatic process : ΔU=-w

Solution:
For cyclic process: ΔU=0⇒q=-w
For isothermal process: ΔU=0⇒q=-w
For adiabatic process: q=0⇒ΔU=w
For isochoric process: w=0⇒ΔU=q

Topic: Chemistry, Thermodynamics (C), JEE Main, JEE Main 2019 (08 Apr Shift 1)
Which one of the following equations of motion represents simple harmonic motion?
Where $\mathrm{k}, \mathrm{k}_0, \mathrm{k}_1$ and $\mathrm{a}$ are all positive

Options:
A Acceleration $=\mathrm{kx}$
B Acceleration $=-\mathrm{k}_0 \mathrm{x}+\mathrm{k}_1 \mathrm{x}^2$
C Acceleration $=-\mathrm{k}(\mathrm{x}+\mathrm{a})$
D Acceleration $=k(x+a)$

The correct answer is:
Acceleration $=-\mathrm{k}(\mathrm{x}+\mathrm{a})$

Solution:
In $\mathrm{SHM}, \mathrm{F}_{\text {restoring }} \propto-\mathrm{X}$

Topic: Physics, Oscillations, NEET, NEET 2009 (Mains)