NEET 2023 | Atoms and Nuclei Question 12 | Physics

The half life of a radioactive substance is 20 minutes. In how much time, the activity of substance drops to $$\left(\frac{1}{16}\right)^{\text {th }}$$ of its initial value?

40 minutes

60 minutes

80 minutes

20 minutes

NEET 2023

MCQ (Single Correct Answer)

-1

In hydrogen spectrum, the shortest wavelength in the Balmer series is $$\lambda$$. The shortest wavelength in the Bracket series is :

$$4 \lambda$$

$$9 \lambda$$

$$16 \lambda$$

$$2 \lambda$$

NEET 2023

MCQ (Single Correct Answer)

-1

The radius of inner most orbit of hydrogen atom is $$5.3 \times 10^{-11} \mathrm{~m}$$. What is the radius of third allowed orbit of hydrogen atom?

1.06 $$\mathop A\limits^o $$

1.59 $$\mathop A\limits^o $$

4.77 $$\mathop A\limits^o $$

0.53 $$\mathop A\limits^o $$

NEET 2022 Phase 2

MCQ (Single Correct Answer)

-1

Let R₁ be the radius of the second stationary orbit and R₂ be the radius of the fourth stationary orbit of an electron in Bohr's model. The ratio $${{{R_1}} \over {{R_2}}}$$ is :

0.25

0.5

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Human Health and Diseases Body Fluids and Its Circulation Locomotion and Movement Neural Control and Coordination Reproduction in Organisms Reproductive Health Structural Organisation in Animals Digestion and Absorption Excretory Products and Their Elimination Chemical Coordination and Integration Human Reproduction Animal Kingdom Breathing and Exchange of Gases Evolution