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- Bhc
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During mean life of a radioactive element, the fraction that disintegrates is
|
(a) e |
(b) |
(c) |
(d) |
The velocity of an electron in the second orbit of sodium atom (atomic number = 11) is v. The velocity of an electron in its fifth orbit will be
|
(a) v |
(b) |
(c) |
(d) |
In a compound microscope, if the objective produces an image Io and the eye piece produces an image Ie, then
|
(a) Io is virtual but Ie is real |
(b) Io is real but Ie is virtual |
|
(c) Io and Ie are both real |
(d) Io and Ie are both virtual |
A man runs towards a mirror at a speed 15 m/s The speed of the image relative to the man is
|
(a) 15 |
(b) 30 |
(c) 35 |
(d) 20 |
When ultraviolet rays are incident on metal plate, then photoelectric effect does not occurs. It occurs by the incidence of
|
(a) X-rays |
(b) Radio wave |
(c) Infrared rays |
(d) Green house effect |