The threshold frequency of a metal corresponds to the wavelength of x nm. In two separate experiments A and B, incident radiations of wavelengths 1/2x nm and 1/4x nm respectively are used. The ratio of kinetic energy of the released electrons in experiment 'B' to that in experiment 'A' is

• 1/3

• 2

• 4

• 3

The minimum values of uncertainties involved in the determination of both the position and velocity of a particle respectively are 1 × 10^-10 m and 1 × 10^-10 ms^-1.Then, the mass (in kg) of the particle is

• 5.270 × 10^-15

• 5.270 × 10^-20

• 5.270 × 10^-16

• 5.270 × 10^-10

The number of electrons with azimuthal quantum number l = 1 and l = 2 for Cr in ground state respectively are

• 12, 5

• 12, 4

• 16, 5

• 16, 4

Which of the following changes in the respective bond order values are caused by removal of an electron from N₂ and F₂ molecules?

• Decrease by 0.5 in both

• Increase by 0.5 in both

• Increase by 0.5 in the former and decrease by 0.5 in the latter

• Decrease by 0.5 in the former and increase by 0.5 in the latter

The correct order of first ionisation enthalpies of the following elements is

• Be > Mg > Ca > Sr > Ra > Ba

• Ra > Ba > Sr > Ca > Mg > Be

• Be > Mg > Ca > Sr > Ba > Ra

• Ra > Sr > Ba > Mg > Ca > Be

The relative strength of trichlorides of boron group to accept a pair of electron is given by

• GaCl₃ > AlCl₃ > BCl₃

• AlCl₃ > BCl₃ > GaCl₃

• AlCl₃ > GaCl₃ > BCl₃

• BCl₃ > AlCl₃ > GaCl₃

The hybridised state of bromine in bromine pentafluoride is

• sp³d

• dsp³

• d²sp³

• sp³d²

In which one of the following, d-d transition involves absorption in the ultraviolet region?

• [Cu(H₂O)₄]²⁺

• [Ti(H₂O)₆]³⁺

• [Co(NH₃)₆]³⁺

• [Co(CN)₆]^3-

The enthalpy change for a reaction at equilibrium is -20.5 kJ mol^-1. Then the entropy change for this equilibrium at 410 K is

• +50 JK^-1mol^-1

• +55 JK^-1mol^-1

• +75 JK^-1mol^-1

• -50 JK^-1mol^-1

The enthalpy of combustion of glucose (mol.wt.: 180 g mol^-1) is -2840 kJ mol^-1. Then the amount of heat evolved when 0.9 g ofglucose is burnt, will be

• 14.2 kJ

• 142 kJ

• 28.4 kJ

• 1420 kJ