List of top NanoScience Questions

Temperature dependence of electron-hole mobility due to lattice scattering varies approximately as :

During ion-implantation, the impurity atoms entering the crystal, gives up their energy to the lattice via collisions. These impurity atoms come to rest at certain average penetration depth known as :

In quantum well, electrons are confined in :

Which of the following conditions should be met while writing the canonical structures of a resonance hybrid ?
A. The magnitude of resonance energy should be low and the hybrid will be more stable
B. The number of unpaired electrons should be same in all the canonical forms
C. Canonical forms where similar charges develop on vicinal atoms are highly significant forms
D. The positions of the nuclei of each canonical form and the hybrid must remain same
E. Only a pair of electrons should be shifted in writing the canonical forms
Choose the correct answer from the options given below :

The known per-oxoacids of Sulphur are :
A. $H_2SO_5$
B. $H_2S_2O_9$
C. $H_3S_4O_{12}$
D. $H_2S_2O_8$
E. $H_2S_2O_7$
Choose the correct answer from the options given below :

Which of the following compounds have chiral carbon ?
A. 1, 1-Dibromopentane
B. 2-Chloro-2-methylpropane
C. 2-Bromopentane
D. 3-Bromopentane
E. 1-fluoro-2-ethylpentane
Choose the correct answer from the options given below :

According to Born-Haber cycle, the acid strength of Halogen depends upon :
A. Enthalpy of dehydration
B. Enthalpy of dissociation
C. Dipole moment
D. Electron affinity $X^-$
E. Metal ion
Choose the most appropriate answer from the options given below :

A process is spontaneous if :
A. $(\Delta G_{\text{system}})_{T, P} = 0$
B. $\Delta S_{\text{system}} + \Delta S_{\text{surrounding}} > 0$
C. $\Delta S_{\text{system}} + \Delta S_{\text{surrounding}} < 0$
D. $(\Delta G_{\text{system}})_{T, P} < 0$
E. $(\Delta G_{\text{system}})_{T, P} > 0$
Choose the correct answer from the options given below :

Which of the following molecules possess V-shape ?
A. $O_3$
B. $N_3^-$
C. $CO_3^{2-}$
D. $NO_2^-$
E. $NO_3^-$
Choose the most appropriate answer from the options given below :

Which of the silanes are formed by the reactions of $Mg_2Si + H_2SO_4 \longrightarrow$
A. $Si_4H_{10}$
B. $Si_3H_8$
C. $Si_5H_{10}$
D. $Si_6H_{14}$
E. $Si_7H_9$
Choose the correct answer from the options given below :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : $\dot{C}H_3$ behave as nucleophiles.
Reason (R) : Odd electron species where unpaired electron is accommodated in a low energy SOMO also behave as nucleophiles.
In the light of the above statements, choose the most appropriate answer from the options given below :

The correct order of nucleophilicity (nucleophilic reactivity) of the given species is :
A. $EtO^-$
B. $Me_3N$
C. $CN^-$
D. $OH^-$
E. $PhO^-$
Choose the correct answer from the options given below :

Choose the correct sequence by arranging the given ions in the order of increasing size :
A. $Cl^-$
B. $Mg^{2+}$
C. $Br^-$
D. $S^{2-}$
E. $Na^+$
Choose the correct answer from the options given below :

Choose the correct sequence on the basis of number of unpaired electrons present in the given field:
A. $Cr(+II)$ in weak field
B. $Co(+II)$ in strong field
C. $Ni(+II)$ in strong field
D. $Pt(+II)$ in weak field
E. $Ag(+II)$ in strong field
Choose the correct answer from the options given below :

Choose the correct sequence of the elements arranged in their increasing order of atomic numbers:
A. Pu
B. Po
C. Pm
D. Pt
E. Pa
Choose the correct answer from the options given below :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Boiling point of cis isomers is higher than trans isomers.
Reason (R) : The Dipole moment of cis isomers is higher than trans isomers.
In the light of the above statements, choose the most appropriate answer from the options given below :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : The Arrhenius equation predicts that the rate constant of a reaction can be decreased by increasing the temperature or by decreasing the activation energy.
Reason (R) : Changing the temperature of a reaction mixture is easy to do, however reducing the activation energy is more challenging in a reaction.
In the light of the above statements, choose the most appropriate answer from the options given below :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : A gas is confined by a piston at pressure '$P$' and the external pressure is $P_{ex}$. If the $P_{ex}$ is measurably greater than internal pressure, then decreasing $P_{ex}$ infinitesimally will not decrease it below the pressure of the gas and will not change the direction of the process.
Reason (R) : The system is in mechanical equilibrium with its surrounding and the compression is thermodynamically reversible.
In the light of the above statements, choose the most appropriate answer from the options given below :

Predict the % product formation in the given reaction :
$CH_3CH_2CBr(CH_3)_2 \xrightarrow{KOH(alc.)} CH_3CH=C(CH_3)_2 \ (X) + CH_3CH_2C(CH_3)=CH_2 \ (Y)$}

The Carbon atom in singlet and triplet carbene is ____________ and ____________ - hybridized, respectively.

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Diastereomers are achiral molecules have superposable mirror images.
Reason (R) : Diastereomers are compounds have different physical properties.
In the light of the above statements, choose the most appropriate answer from the options given below :

An electric current of 0.50A from a 12V supply is passed for 300 sec through a resistance in thermal contact with water and the water is allowed to boil under a pressure of 1.0 atm. The value of enthalpy change during the process, if 0.798 gm of water is vaporised, will be :

Evaporation of water taking place at $100^\circ\text{C}$ at 1 atm. pressure, the correct choice of change in $\Delta S$ for system and surrounding would be :

The integrated rate law and half-life equation for an first order reaction would be :

The $K_a$ value of acetic acid is $1.8 \times 10^{-5}$. What would be the degree of ionization of 0.02 M acetic acid, containing 0.01 M Sodium acetate in it?}