﻿ A 25 W bulb emits monochromatic yellow light of wavelength of 0.5

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# 11.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

A.

7.169 x 1019

25 watt = 25 Js-1

E = NHv = $\frac{\mathrm{NHc}}{\mathrm{\lambda }}$

25 =

N = 7.169  x 1019 quanta s-1

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 , $±\frac{1}{2}$

• 3 , 0 , 0 , $±\frac{1}{2}$

13.

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

14.

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

15.

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

16.

Which of the following compounds is the weakest Bronsted base ?

17.

Which one ofthe following is not tetrahedral in shape ?

• SiCl4

• N${\mathrm{H}}_{4}^{+}$

• CH4

• SF4

18.

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

• one

• three

• five

• seven

19.

N2O is isoelectronic to CO2 and ${\mathrm{N}}_{3}^{-}$. Which of the following is the structure of N2O ?

• N-O-N

• N-N-O

20.

Number of lone pair in XeOF4 is :

• zero

• one

• two

• three