Assume that the radius of the first Bohr orbit of hydrogen atom is $0.6Å$. The radius of the third Bohr orbit of $He^+$is _______ picometer. (Nearest Integer)
Correct Answer: 270
Solution and Explanation
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Identify the correct statements about alkali metals
A. The order of standard reduction potential $\left( M ^{+} \mid M \right)$ for alkali metal ions is $Na > Rb > Li$.
B. $CsI$ is highly soluble in water.
C. Lithium carbonate is highly stable to heat.
D. Potassium dissolved in concentrated liquid ammonia is blue in colour and paramagnetic.
E. All the alkali metal hydrides are ionic solids.
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Electrons in a cathode ray tube have been emitted with a velocity of $1000\, m s ^{-1}$ The number of following statements which is/are true about the emitted radiation is _______ Given : $h =6 \times 10^{-34} J s , m _e=9 \times 10^{-31} kg$
(A) The deBroglie wavelength of the electron emitted is $66667 nm$
(B) The characteristic of electrons emitted depend upon the material of the electrodes of the cathode ray tube
(C) The cathode rays start from cathode and move towards anode
(D) The nature of the emitted electrons depends on the nature of the gas present in cathode ray tube
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