13. Nuclei - CBSE STD 12 Science Physics Questions

871

Questions

1

Question groups

5

Question types

01

M.C.Q (1 Marks)

871 Q→

Sample Questions

13. Nuclei questions

One sample from each question group in this chapter. Select any group above to see the full set with answer keys.

Q 1M.C.Q (1 Marks)1 Mark

${ }_{82}^{290} X \xrightarrow{\alpha} Y \xrightarrow{e^{+}} Z \xrightarrow{\beta^{-}} P \xrightarrow{e^{-}} Q$

In the nuclear emission stated above, the mass number and atomic number of the product $Q$ respectively, are

A
$286,80$
B
$288,82$
✓
$286,81$
D
$280,81$

Answer: C.

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Q 2M.C.Q (1 Marks)1 Mark

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

✓
$80$
B
$20$
C
$40$
D
$60$

Answer: A.

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Q 3M.C.Q (1 Marks)1 Mark

A nucleus of mass number $189$ splits into two nuclei having mass number $125$ and $64$ . The ratio of radius of two daughter nuclei respectively is:

A
$4: 5$
✓
$5: 4$
C
$25: 16$
D
$1: 1$

Answer: B.

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Q 4M.C.Q (1 Marks)1 Mark

Given below are two statements :

Statement $I:$ The law of radioactive decay states that the number of nuclei undergoing the decay per unit time is inversely proportional to the total number of nuclei in the sample.

Statement $II:$ The half life of a radionuclide is the sum of the life time of all nuclei, divided by the initial concentration of the nuclei at time $t =0$.

In the light of the above statements, choose the most appropriate answer from the options given below :