The decay constant of a radio isotope is λ. If A₁ and A₂ are its activities at time

⇦

⇨

The decay constant of a radio isotope is λ. If A₁ and A₂ are its activities at time t₁ and t₂ respectively, the number of nuclei which have decayed during the time (t₁ – t₂):

Options

(a) λ (A₁ – A₂)
(b) A₁t₁ -A₂t₂
(c) A₁ – A₂
(d) (A₁ – A₂) / λ

Correct Answer:

(A₁ – A₂) / λ

Explanation:

Activity is given by A = dN/ dt = -λN
Activity at time t₁ is A₁ = – λN₁
and activity at time t₂ is A₂ = -1 N₂ as t₁ > t₂ therefore, number of atoms remained after time t₁ is less than that remained after time t₂.
That is, N₁ < N₂. number of nuclei decayed in (t₁ - t₂) = N₂ - N₁ = (A₁ - A₂) / λ

Related Questions:

1. If the wavelength of incident light falling on a photosensitive material decreases,
2. An ideal gas is compressed to half its initial volume by means of several processes.
3. Given the value of Rydberg constant is 10⁷ m⁻¹, the wave number of the last line
4. Three capacitors each of capacitance C and of breakdown voltage V are joined in series
5. The innermost orbit of hydrogen atom has a diameter 1.06Å. The diameter of tenth

Topics: Atoms and Nuclei (136)
Subject: Physics (2479)

---

Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score

18000+ students are using NEETLab to improve their score. What about you?

Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.

---

Share this page with your friends