- A10
- B25
- C15
- D22
Explanation:
Atomic number of any element is equal no of electron.
Atomic no. = no. of proton = no of electron.
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In Bohr model of hydrogen atom, the ratio of periods of revolution of an electron in n = 2 and n = 1 orbits is
|
(a) 2 : 1 |
(b) 4 : 1 |
(c) 8 : 1 |
(d) 16 : 1 |
A primary cell has an e.m.f. of 1.5 volts, when short-circuited it gives a current of 3 amperes. The internal resistance of the cell is
|
(a) 4.5 ohm |
(b) 2 ohm |
(c) 0.5 ohm |
(d) 1/4.5 ohm |
A railway compartment is lit up by thirteen lamps each taking 2.1 amp at 15 volts. The heat generated per second in each lamp will be
|
(a) 4.35 cal |
(b) 5.73 cal |
(c) 7.5 cal |
(d) 2.5 cal |
The resistance of a reverse biased P-N junction diode is about
|
(a) 1 ohm |
(b) |
(c) |
(d) |