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MODUL • Fizik TINGKATAN 5

(v) Justifikasi jawapan anda bagi (c)(iv). / Justify your answer to (c)(iv).

1 Pada 5 cm, bacaan daripada pengesan meningkat dengan cepat.
At 5 cm, the reading from detector increase rapidly.
2 Dalam skala/bilangan yang besar, menunjukkan kewujudan zarah α.

In large scale/ number, shows the existing of α-particles.

2 Polonium-210 adalah satu radioisotop bagi polonium. Suatu sampel radioisotop yang mengandungi 400 g Polonium-210
mengalami proses reputan. Setengah-hayat Polonium-210 adalah 140 hari.
Polonium-210 is a radioisotope of polonium. A radioisotope sample that contains 400 g of Polonium-210 undergoes a decay process.
The half-life of Polonium-210 is 140 days.
(a) Apakah maksud setengah-hayat? / What is the meaning of half-life?

Setengah hayat ialah masa yang diambil untuk jisim/aktiviti radioisotop menjadi separuh daripada nilai jisim/aktiviti
asalnya.

Half-life is the time taken for the mass/activity of radioisotope to become half of its mass/activity.
(b) Beri satu sebab mengapa Polonium-210 mengalami proses reputan.
State one reason why Polonium-210 undergoes a decay process.
Untuk menjadi lebih stabil. / To become more stable.

(c) (i) Hitung jisim Polonium-210 selepas 420 hari. / Calculate the mass of Polonium-210 after 420 days.

400 g 140 200 g 140 100 g 140 50 g
T 1 T 1 T 1
— — —
2 2 2
Selepas 420 hari, jisim Polonium-210 yang masih aktif = 50 g.
After 420 days, the mass of Polonium-210 that is still active = 50 g.

(ii) Pada Rajah 2, lakar graf untuk menunjukkan proses reputan Polonium-210.
On Diagram 2, sketch a graph to show the decay process of Polonium-210.

Jisim (g)
Mass (g) UNIT 5
UNIT 5
400

300

200

100
Maklumat tambahan:
Additional information: 50
Masa/hari
0 100 200 300 400 Time/days

Rajah 2 / Diagram 2

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