If the kinetic energy of a particle is reduced to half, de-Broglie wavelength becomes

• 2 times

• $\frac{1}{\sqrt{2}}$ times

• 4 times

• $\sqrt{2}$ times

In an atom the order of increasing energy of electrons with quantum numbers

(i) n=4, l=1      (ii) n=4, l=0     (iii) n=3, l=2 and (iv) n=3, l=1 is

• III < I <IV < II

• II < IV < I<III

• I <III <II <IV

• IV< II <III <I

The number of angular and radial nodes of 4d orbital respectively are

• 3,1

• 1,2

• 3,0

• 2,1

The product of uncertainty in velocity and uncertainty in position of a micro particle of mass 'm' is not less than in which of the following?

• h × $\frac{3\mathrm{\pi }}{\mathrm{m}}$

• $\frac{\mathrm{h}}{3\mathrm{\pi }}$× m

• $\frac{\mathrm{h}}{4\mathrm{\pi }} \times \frac{1}{\mathrm{m}}$

• $\frac{\mathrm{h}}{4\mathrm{\pi }} \times \mathrm{m}$

2p orbitals have

• n = 1; l = 2

• n = 1; l = 0

• n = 2; l = 1

• n = 2; l = 0

126.

Aufbau principle is not satisfied by

• Cr and Cl

• Cu and Ag

• Cr and Mg

• Cu and Na

Neutrons are found in atoms of all elements except in

• chlorine

• oxygen

• argon

• hydrogen

The atomic weight of an element is 39. The number of neutrons in its nucleus is one more than the number of protons. The number of protons, neutrons and electrons-respectively in its atoms would be

• 19, 20, 19

• 19, 19, 20

• 20, 19, 19

• 20, 19, 20

The energy and radius of electron present in second orbit of He⁺ respectively are

• -109 × 10^-18J, 105.8 pm

• -872 × 10^-18 J, 211.6 pm

• -4.36 × 10^-18 J, 52.9 pm

• -2.18 × 10^-18 J, 105.8 pm

Assertion (A): Na⁺ and Mg²⁺ ions are isoelectronic but the ionic radius of Na⁺ is greater than that of Mg²⁺.

Reason (R): The effective nuclear charge of Na⁺ ion is less than that of Mg²⁺ ion.

• Both (A) and (R) are correct but (R) is not the correct explanation of (A)

• Both (A) and (R) are correct and (R) is correct explanation of (A).

• (A) is not correct but (R) is correct.

• (A) is correct but (R) is not correct.