[1 Mark Question Answer]

Question 11 Mark

(a) Mention one use and one harmful effect of radioactivity.
(b) Give one source of background radiation

Answer

(a) Useful : Under medical supervision radioactivity is used in curing cancer.
Harmful : Exposure to radioactivity can cause cancer and even death.
(b) Radioactivity in the earth is the source of background radiation.

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Question 21 Mark

(a) Which of the radioactive radiations can cause severe genetical disorders?
(b) Which of the radioactive radiations are deflected by an electric field?
(c) Name the radiation which is used in carbon dating.

Answer

(a) Gamma radiations.
(b) Alpha and beta radiations.
(c) $\gamma$-radiation is used in carbon dating.

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Question 31 Mark

(a) What do you understand by the term nucleons?
(b) Which of the radionctive radiations:
(i) can cause severe genetical disorders,
(ii) are deflected by an electric field?

Answer

(a) Neutrons and protons are collectively called nueleons.
(b) (i) Gamma radiations
(ii) Alpha and beta radiations

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Question 41 Mark

(a) What do you understand by the term nucleus?
(b) A radioactive nucleus undergoes a series of decays according to the sequence
$X \xrightarrow{\beta} X_1 \xrightarrow{\alpha} X_2 \xrightarrow{a} X_3 .$
If the mass number and atomic number of $X _3$ are 172 and 69 respectively, what is the mass number and atomic number of X ?

Answer

(a) The central core of the atom is called nucleus. The nucleus contains protons and neutrons.
(b) ${ }_{69}^{17} X _3 \xrightarrow{+\alpha}{ }_{71}^{176} X _2$;
${ }_{71}^{176} X _2 \xrightarrow{+\alpha}{ }_{71}^{180} X _1 ;$
${ }_n^{10} X \xrightarrow{+\beta}{ }_n^{120} X$
Thus, mass number of $X$ is 180 and atomic number $7 2$;

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Question 51 Mark

Why can nuelear fusion not be possible to generate electricity?

Answer

Nuclear fusion requires a pressure of millions of atmosphere and millions of degree celsius temperature, which is not possible. Furthermore, there is no material available to withstand such high temperature and pressure in which nuclear fusion can be carried out.

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Question 61 Mark

When does the nucleus of an atom tend to be radioactive?

Answer

The nucleus of an atom tends to be radioactive when:
(a) its atomic number exceeds 82.
(b) there is an imbalance of protons and neutrons as compared to a normal stable atom.

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Physics [1 Mark Question Answer]

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