In a radioactive change R →-α X &r

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161.

In a radioactive change R -α X -β Y -β Z. R and Z.

  • isotopes

  • isobars

  • isomers

  • isotones


A.

isotopes

RBA  -α XB-4A-2  -β YB-4A-1 -βZB-4A

R and Z have same atomic number, but different mass number, hence these are isotopes.


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162.

nXemit one α and two β- particles. It is converted into

  • nXm - 4

  • n - 1Xm - 1

  • nZm - 4

  • None of these


163.

Increasing order (lowest first) for the values of e/m for electron (e), proton (p), neutron (n) and α-particles is

  • e, p, n, α

  • n, α, p, e

  • n, p, e, α

  • n, p, α, e


164.

A particle moving with a velocity 106 m/s will have de-Broglie wavelength nearly [Given, m= 6.62 × 10-27 kg, h =  6.62 × 10-34 J-s]

  • 10-9m

  • 10-13 m

  • 10-19 m

  • 1 Å


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165.

From the given sets of quantum numbers, the one that is inconsistent with the theory is

  • n =3; l =2; m = -3; s = +12

  • n = 4; l = 3; m = 3; s = +12

  • n = 2; l = 1; m = 0; s = -12

  • n = 4; l = 3; m = 2; s = +12


166.

In the following particle

3Li6 + ? → 2He41H3

the missing particle is

  • electron

  • neutron

  • proton

  • deuteron


167.

Bohr's radius of 2nd orbit of Be3+ is equal to that of

  • 4th orbit of hydrogen

  • 2nd orbit of He+

  • 3rd orbit of Li2+

  • first orbit of hydrogen


168.

The sky looks blue due to

  • dispersion effect

  • reflection

  • transmission

  • scattering


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169.

A radioactive substance disintegrate its 90% in 100 days. How much time it will take to disintegrate its 99.9% ?

  • 100 days

  • 200 days

  • 300 days

  • 400 days


170.

The wavelength of an electron having kinetic energy equal to 4.55 × 10-25 J is (h = 6.6 × 10-34 kgm2s-1, mass of electron = 9.1 × 10-31 kg)

  • 7.25 × 10-7 nm

  • 725 nm

  • 7.25 × 10-7 m

  • 7.25 × 107 nm


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