11. Which of the following has a least penetrating power?
A. All have same penetrating power
B. Beta Particles
C. Alpha particles
D. Gamma rays
12. The isotope of uranium capable of sustaining chain reaction is
A. U-235
B. U-245
C. U-239
D. U-238
13. The age of most ancient geological formations is estimated by
A.Ra – Si method
B.Potassium – argon method
C.C14 method
D.Uranium – lead method
14. Who suggested that most of the mass of the atom is located in the nucleus?
A. Thompson
B. Bohr
C. Rutherford
D. Einstein
15. The dark lines in the solar spectrum are due to
A. absorption of corresponding wavelengths by the outer layers of the sun
B. destructive interference between waves of certain definite wavelengths
C. absorption of corresponding wavelengths by the prism used in the photograph
D. absence of corresponding wavelengths from the light emitted by the core of the sun