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Modern Physics

104 Questions Start DPT Test
All Exams DPT (104)
Q101 DPT Radioactivity MCQ
03 Oct 2026
Concept
The amount of active substance reduces to $1 / 64$ of its initial value in $15$ hours. What is the half life?
A.
$1.5$ hours
B.
$2.0$ hours
C.
$2.5$ hours
D.
$3.0$ hours
Q102 DPT Radioactivity MCQ
03 Oct 2026
Concept
How many $\alpha$ and $\beta$ particles are emitted when $_{90}\text{Th}^{232}$ converts to $_{82}\text{Pb}^{208}$?
A.
$5 \alpha$ and $3 \beta^-$
B.
$6 \alpha$ and $4 \beta^-$
C.
$4 \alpha$ and $6 \beta^-$
D.
$7 \alpha$ and $2 \beta^-$
Q103 DPT Radioactivity MCQ
03 Oct 2026
Concept
A radioactive nucleus decays as $X \xrightarrow{\alpha} X_1 \xrightarrow{\beta^-} X_2 \xrightarrow{\alpha} X_3 \xrightarrow{\gamma} X_4$. If mass number and charge number of $X$ are $180$ and $72$ then find these values of $X_4$.
A.
Mass number $170$, Charge number $68$
B.
Mass number $172$, Charge number $69$
C.
Mass number $174$, Charge number $70$
D.
Mass number $176$, Charge number $71$
Q104 DPT Radioactivity MCQ
03 Oct 2026
Concept
The mean life of a radioactive material for $\alpha$ and $\beta$ decay are $1620$ years and $520$ years. What is the half life of sample.
A.
$215$ years
B.
$273$ years
C.
$320$ years
D.
$394$ years