For an electron , if the uncertainty in velocity is $∆$v , the uncertainty in its position ($∆$x)  is given by :

• $\frac{\mathrm{hm}}{4\mathrm{\pi }∆\mathrm{\nu }}$

• $\frac{4\mathrm{\pi }}{\mathrm{hm}∆\mathrm{\nu }}$

• $\frac{\mathrm{h}}{4\mathrm{\pi m}∆\mathrm{v}}$

• $\frac{4\mathrm{\pi m}}{\mathrm{h}∆\mathrm{\nu }}$

The K_sp of Mg(OH)₂ is 1 x 10^-12 , 0.01 M Mg(OH)₂ will precipitate at the limited pH :

• 3

• 9

• 5

• 8

Equation of Boyle's law is :

• $\frac{\mathrm{dP}}{\mathrm{P}}$ = -$\frac{\mathrm{dV}}{\mathrm{V}}$

• $\frac{\mathrm{dP}}{\mathrm{P}}$ = +$\frac{\mathrm{dV}}{\mathrm{V}}$

• $\frac{{\mathrm{d}}^2\mathrm{P}}{\mathrm{P}}$ = -$\frac{\mathrm{dV}}{\mathrm{dT}}$

• $\frac{{\mathrm{d}}^2\mathrm{P}}{\mathrm{P}}$ = +$\frac{{\mathrm{d}}^2\mathrm{V}}{\mathrm{dT}}$

A radioactive sample is emitting 64 times radiations than non-hazardous limit .If its half-life is 2 hours , after what time it becomes non- hazardous ?

• 16 h

• 10 h

• 12 h

• 8 h

A metal surface is exposed to solar radiations :

• the emitted electrons have energy less than a maximum value of energy depending upon frequency of incident radiations

• the emitted electrons have energy less than maximum value of energy depending upon intensity of incident radiations

• the emitted electrons have zero energy

• the emitted electrons have energy equal to energy of photons of incident light

Which of the following transitions have minimum wavelengths ?

• n₄ $\to$ n₁

• n₂ $\to$ n₁

• n₄ $\to$ n₂

• n₃ $\to$ n₁

Orbital is :

• circular path around the nucleus in which the electrons revolves

• space around the nucleus where the probability of finding the electron is maximum

• amplitude of electron wave

• none of the above

Which of the following sequence is correct as per Aufbau principle ?

• 3s < 3d < 4s < 4p

• ls < 2p < 4s < 3d

• 2s < 5s < 4p < 5d

• 2s < 5s < 4p < 5f

Ionic compounds are formed most easily with :

• low electron affinity , high ionisation energy

• high electron affinity , low ionisation energy

• low electron affinity , low ionisation energy

• high electron affinity , high ionisation energy

The enthalpy change ($∆$H) for the neutralisation of M HCl by caustic potash in dilute solution at 298 K is :

• 68 kJ

• 65 kJ

• 57.3 kJ

• 50 kJ