A 25 W bulb emits monochromatic yellow light of wavelength of 0.57 $\mathrm{\mu }$m. Calculate the rate of emission of quanta per second.

• 7.169 x 10¹⁹

• 4.569 x 10¹⁹

• 8.579 x 10¹⁹

• 9.662 x 10¹⁹

12.

The correct set of quantum numbers for the unpaired electron of a chlorine atom is :

• 2 , 0 , 0 , +$\frac{1}{2}$

• 2 , 1 , -1 , +$\frac{1}{2}$

• 3 , 1 , -1 , $\pm \frac{1}{2}$

• 3 , 0 , 0 , $\pm \frac{1}{2}$

Calculate the radius of a water molecule assuming to be spherical (density= 1 g mL^-1) :

• 1.925 10^-8 cm

• 1.925x 10^-9 cm

• 1.925 10^-10 cm

• 1.925 10^-11 cm

When 6 g of a monobasic acid is dissolved in 100 mL solution , it is l N. What is equivalent mass of the acid ?

• 20 g equiv^-1

• 40 g equiv^-1

• 60 g equiv^-1

• 80 g equiv^-1

Each NH₃ molecule has six other NH₃ molecules as nearest neighbours in solid state ; $∆$H of sublimation of NH₃ molecule at the m.p. is 30.8 kJ mol^-1 and in the absence of H-bonding estimated Ml of sublimation is 14.4 kJ mol^-1 .Hence , strength of H-bond in solid NH₃ is :

• 5.47 kJ mol^-1

• 10.93 kJ mol^-1

• 16.40 kJ mol^-1

• - 16.40 kJ mol^-1

Which of the following compounds is the weakest Bronsted base ?

Which one ofthe following is not tetrahedral in shape ?

• SiCl₄

• N${\mathrm{H}}_4^{+}$

• CH₄

• SF₄

When 2.495 g of CuSO₄ · x H₂O (molar mass 249.5) is heated, 0.05 mole of H₂O is lost. Therefore , x is :

• one

• three

• five

• seven

N₂O is isoelectronic to CO₂ and ${\mathrm{N}}_3^{-}$. Which of the following is the structure of N₂O ?

• 

• N-O-N

• N-N-O

• 

Number of lone pair in XeOF₄ is :

• zero

• one

• two

• three