Blog Log in Get Started Free

Physics MCQs for NEET — Practice Questions with Answers

Practice free Physics NEET multiple-choice questions online with instant answers and detailed explanations. No login required.

All Physics Chemistry Botany Zoology

Chapter Language Difficulty Show only questions I answered incorrectly Register free to filter questions

● ● ● ● ●

The equation ${}_{Z}^{A}X \to {}_{Z + 1}^{A}Y + {}_{- 1}^{0}e + \bar{v}$ represents-

$β$ -emission

$α$ -emission

$e^{-}$ capture

Fission

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(a) It is a $β - d e c a y$ as the atomic number(Z) increases by one.

● ● ● ● ●

The activity of a sample of a radioactive material is $A_{1}$ , at time $t_{1}$ and $A_{2}$ at time $t_{2}$ ( $t_{2}$ > $t_{1}$ ). If its mean life T, then

$A_{1} t_{1} = A_{2} t_{2}$

$A_{1} - A_{2} = t_{2} - t_{1}$

$A_{2} = A_{1} e^{(t_{1} - t_{2}) / T}$

$A_{2} = A_{1} e^{(t_{1} / t_{2}) T}$

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

So $A_{1} = A_{0} e^{- t_{1} / T} \Rightarrow A_{0} = \frac{A_{1}}{e^{- t_{1} / T}} = A_{1} e^{t_{1} / T}$

$∴ A_{2} = A_{0} e^{- t / T} = (A_{1} e^{t_{1} / T}) e^{- t_{2} / T} \Rightarrow A_{2} = A_{1} e^{(t_{1} - t_{2}) / T}$

● ● ● ● ●

Nucleus produced due to $α$ -decay of the nucleus ${}_{Z}^{A}X$ is

${}_{Z + 2}^{A + 4}Y$

${}_{Z}^{A}Y$

${}_{Z - 2}^{A - 4}Y$

${}_{Z - 4}^{A - 2}Y$

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

● ● ● ● ●

The half-life of ${}_{215}{At}$ is 100 $μs$ . The time taken for the radioactivity of a sample of ${}_{215}{At}$ to decay to 1/16th of its initial value is

400 $μs$

6.3 $μs$

40 $μs$

300 $μs$

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(a) The radioactivity of a sample decays to $\frac{1}{16} th$ of its initial value in four half lives.

● ● ● ● ●

The half-life of a radioactive substance is 48 hours. How much time will it take to disintegrate to its $\frac{1}{16}$ th part

12 h

16 h

48 h

192 h

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(d) $\frac{N}{N_{0}} - {(\frac{1}{2})}^{t / T} \Rightarrow \frac{1}{16} = {(\frac{1}{2})}^{t / 48}$

$\Rightarrow {(\frac{1}{2})}^{4} = {(\frac{1}{2})}^{t / 48} \Rightarrow t = 192 hour$

● ● ● ● ●

A radioactive substance has an average life of 5 hours. In a time of 5 hours

Half of the active nuclei decay

Less than half of the active nuclei decay

More than half of the active nuclei decay

All active nuclei decay

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(c) If $λ$ is the decay constant of a radioactive substance than average life = $\frac{1}{λ}$
Also half life = $\frac{0.693}{λ} = 0.693 \times (A v e r a g e l i f e)$
in single average life, more than 63% of radioactive nuclei decay

● ● ● ● ●

Which of the following radiations has the least wavelength

X-rays

$γ$ -rays

$β$ -rays

$α$ -rays

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(b) $γ$ -rays have least wavelength.

● ● ● ● ●

A radioactive sample at any instant has its disintegration rate 5000 disintegration per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is

0.8 In 2

0.4 In 2

0.2 In 2

0.1 In 2

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(b) $λ = \frac{\log_{e} \frac{A_{1}}{A_{2}}}{t} = \frac{\log_{e} \frac{5000}{1250}}{5} = 0.4 \ln 2$

● ● ● ● ●

A nucleus with Z = 92 emits the following in a sequence:
$α, β^{-}, β^{-}, α, α, α, α, α, β^{-}, β^{-}, α, β^{+}, β^{+}, α$ . The Z of the resulting nucleus is

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

● ● ● ● ●

Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called

Gamma camera

CAT scan

Radiotracer technique

Gamma ray spectroscopy

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(c) Radioactive nuclei that are injected into a patient collected at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiation can then be recorded by a detector. This procedure provides an important diagnostic tool called radio tracer technique.

Ready to ace NEET?

Free access · No credit card required

Browse All Questions Create Free Account

Frequently Asked Questions

Yes. You can attempt every Physics question on this page for free without logging in, and check the correct answer with a detailed explanation instantly.

No account is required to attempt questions and view answers. A free account adds bookmarks, personal notes, and progress tracking.

The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.