Ratio of radii of second and first Bohr orbits of H atom is

• 2

• 4

• 3

• 5

India conducted an underground nuclear test at

• Narora

• Tarapur

• Pushkar

• Pokharan

Dual nature of particle was-given by

• Bohr theory

• Thomson model

• Heisenberg principle

• de-Broglie equation

A golf-ball weigh 40.0 gm. If it is moving with a velocity of 20.0 ms^-1, it's de-Broglie wavelength is

• 1.66 x 10^-34 nm

• 8.28 x 10^-32 nm

• 8.28 x 10^-25 nm

• 1.66 x 10^-24 nm

65.

Which is the shortest wavelength line in the Lyman series of the hydrogen spectrum? (R= 1.097 x 10^-2 nm^-1)

• 94.21 nm

• 91.16 nm

• 911.6 nm

• 933.6 nm

Which of the following order of ionisation energy is correct?

• B < Be < N < C

• Be > B > C > N

• B < Be < C < N

• Be < B < C < N

An element 'Y' emits one $\mathrm{\alpha }$-and two $\mathrm{\beta }$- particles to give 'X'. X and Y are

• isotones

• isobars

• isotopes

• isoelectronics

Consider the following pairs of ions:

I. Sc³⁺ and Ti⁴⁺        II. Mn²⁺ and Fe²⁺

III. Fe²⁺ and Co³⁺    IV. Cu⁺ and Zn²⁺

Among these pairs ofions, isoelectronic pairs would include:

• II, III and IV

• I, III and IV

• I, II and IV

• I, II and III

The line spectrum of He⁺ ion will resemble that of :

• hydrogen atom

• Li⁺ ion

• helium atom

• lithium atom

A body of mass x kg is moving with a velocity of 100 ms^-1. Its de-Broglie wavelength is 6.62 x 10^-35 m. Hence, x is :

[h = 6.62 x 10^-34Js]

• 0.1 Kg

• 0.25 Kg

• 0.15 Kg

• 0.2 Kg