A radioactive sample at any instant has its disintegration rate 5000 disintegration per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is
|
(a) 0.8 In 2 |
(b) 0.4 In 2 |
(c) 0.2 In 2 |
(d) 0.1 In 2 |
(b) 0.4 In 2
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The output of OR gate is 1
|
(a) If both inputs are zero |
(b) If either or both inputs are 1 |
|
(c) Only if both input are 1 |
(d) If either input is zero |
Consider an electron (m = 9.1 
confined by electrical forces to move between two rigid walls separated by 1.0 
metre, which is about five atomic diameters. The quantised energy value for the lowest stationary state is
|
(a) 12 |
(b) 6.0 |
(c) 6.0 |
(d) 6 Joule |
A person cannot see distinctly at the distance less than one metre. Calculate the power of the lens that he should use to read a book at a distance of 25 cm
|
(a) + 3.0 D |
(b) + 0.125 D |
(c) – 3.0 D |
(d) + 4.0 D |
Three plates of common surface area A are connected as shown. The effective capacitance will be
|
(a) |
(b) |
(c) |
(d) |
The energy of a photon of light of wavelength 450 nm is
|
(a) 4.4 |
(b) 2.5 |
(c) 1.25 |
(d) 2.5 |
An uncharged sphere of metal is placed in between two charged plates as shown. The lines of force look like
→The ground state energy of hydrogen atom is – 13.6 eV. What is the potential energy of the electron in this state
| (a) 0 eV | (b) – 27.2 eV | (c) 1 eV | (d) 2 eV |
When a radioactive substance emits an a -particle, its position in the periodic table is lowered by
|
(a) One place |
(b) Two places |
(c) Three places |
(d) Four places |
