| ⇦ | 
| ⇨ |
A mixture consists of two radioactive materials A₁ and A₂ with half lives of 20s and 10s respectively. Initially the mixture has 40 g of A₁ and 160 g of A₂. The amount of the two in the mixture will become equal after:
Options
(a) 60 s
(b) 80 s
(c) 20 s
(d) 40 s
Correct Answer:
40 s
Explanation:
Let, the amount of the two in the mixture will become equal after t years.
The amount of A₁, which remains after t years N₁ = N₀₁ / (2)ᵗ/²⁰
The amount of A₂, which remains after t years N₂ = N₀₂ / (2)ᵗ/¹⁰
According to the problem N₁ = N₂
40 / (2)ᵗ/²⁰ = 160 / (2)ᵗ/¹⁰ ⇒ 2ᵗ/²⁰ = 2(ᵗ/¹⁰⁻²)
t/20 = t/10 – 2 ⇒ t/20 – t/10 = 2
t/20 = 2 ⇒ t = 40 s
Related Questions: - A charged particle with a velocity 2×10³ ms⁻¹ passes undeflected through electric field
- A liquid boils when its vapour pressure equals
- The magnetic moment has dimensions of
- When a charged oil drop moves upwards in an electric field,
- If threshold wevelength for sodium is 6800 Å, the work function will be
Topics: Radioactivity
(83)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A charged particle with a velocity 2×10³ ms⁻¹ passes undeflected through electric field
- A liquid boils when its vapour pressure equals
- The magnetic moment has dimensions of
- When a charged oil drop moves upwards in an electric field,
- If threshold wevelength for sodium is 6800 Å, the work function will be
Topics: Radioactivity (83)
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
Leave a Reply