# TN 12TH PHYSICS - Online Test

Q1. In which of the following , NH3 is not used?
Explaination / Solution:
No Explaination.

Q2. Sc( Z=21) is a transition element but Zinc (z=30) is not because
Explaination / Solution:
No Explaination.

Q3. The sum of primary valance and secondary valance of the metal M in the complex [ M ( en)2 ( Ox)] Cl is L
Explaination / Solution:

In the complex [M (en)2 (Ox)] Cl For the central metal ion M3+

The primary valance is = +3

The secondary valance = 6

sum of primary valance and secondary valance = 3+6 = 9

Q4. Graphite and diamond are
Explaination / Solution:
No Explaination.

Q5. For a first order reaction A → B the rate constant is x min1 . If the initial concentration of A is 0.01M , the concentration of A after one hour is given by the expression.
Explaination / Solution: In this case

k = x min−1 and [A0] = 0.01M = 1 × 10−2M

t = 1 hour = 60 min

[A]= 1 × 10−2 ( e−60x)

Q6. The speed of light in an isotropic medium depends on,
Explaination / Solution:

c = vλ, v is independent of medium

Q7. A plane glass is placed over a various coloured letters (violet, green, yellow, red) The letter which appears to be raised more is,
Explaination / Solution:

The refractive index (n) of the glass is different for different colours. For violet n is high. ∴ Violet travel with low speed, so deviation is high.

Q8. Two identical point charges of magnitude –q are fixed as shown in the figure below. A third charge +q is placed midway between the two charges at the point P. Suppose this charge +q is displaced a small distance from the point P in the directions indicated by the arrows, in which direction(s) will +q be stable with respect to the displacement? Explaination / Solution:

Hint: Since V=0 along equatorial line
Q9. The wavelength λe of an electron and λp of a photon of same energy E are related by
Explaination / Solution:

de Broglie wavelength for an electron

λe= h / √(2mE) ;

λe 1/√E ;

λe2 1/E  ------------- (1)

For photon

λp= hc / E ;

λp 1/E  ------------- (2)

From equation (1) and (2), we have So,

λp λe2

Q10. The following graph shows current versus voltage values of some unknown conductor. What is the resistance of this conductor? Explaination / Solution: 