關於中二I.S. 題

Chan

2008-06-06 8:22 pm

以下全部ＭＣ題:
(1) Why is hydogen preferred as fuel fo rockets?
(i) Liquild hydrogen is lighter then solid fuel.
(ii) Burning hydogen does not contaminate the air
(iii) Hydrogen is odourless

A. (i) only B. (ii)only
C. (i) and (ii) D. (iii)only

(2)Why is liquid oxygen used in some rockets?
A. Burning hydogen requires oxygen and there is no oxyen in space
B. Burning oxygen can produce a large pushing force for the rocket.
C. Liquid oxygen is odourless.

回答 (1)

Uncle Michael

2008-06-06 9:33 pm

✔ 最佳答案

(1) The answer is C.

(i) correct
Because hydrogen is lighter than solid fuel, the rockets using hydrogen as fuel is lighter than that using solid fuel.

(ii) correct
Burning hydrogen gives water as the only product. Water does not contaminate the air.

(iii) incorrect
Since hydrogen is almost completely burned, the odour of hydrogen is not a major factor concerned.

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(2) The answer is A.

A. correct
Hydrogen must be burned in oxygen (or air containing oxygen). Furthermore, sufficient supply of oxygen can make hydrogen completely burned.

B. incorrect
Oxygen cannot burn. Oxygen supports burning only.

C. incorrect
Since oxygen is almost completely used in burning of hydrogen, the odour of oxygen is not a major factor concerned.

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