1967-11-08 — Page 13

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箕一第張四集

日七初月十年来丁屋買

1968

英文中

中學會考試題預習專欄

化學科

·王錦釗

Chemistry (2)

CITY

明星

「爲優秀的人材.. 大辦理因好質素的學校,培養未滿一代

[#44-W-HEEL € 115km - sR ||-HAKEER-HKTE-DE-HR 【高校,黃灣上午學校 校一九六六年度計 全完三校下午,眞光學校,基養上午校 -HEL RECHER ,全一校,全第二校,全完三校上午,

· 故育族素小學:拔臣基校,在侦校

赫针衮,所列學校如下, MEKENDURENTSKKBED.

| 小學校,故實起茨爾本身些協命,尤算方

協和學後,軌服務百一十七名。 華雲院、英幫女座等選一九六六年, ELIIKE* * *******

英兵貴院等四間● 幼貔園生一千四百分 陕會有關學校;"二名,小生二年八 學、蓋協實用中寧、二百四十九名,其中一 何福堂書院、基智中上述一生八姁共四千 MNKARI*--• 校等簡稚園,上水堂幼稚 | 荔灣午校,羞爾上午,無無機,全完堂 一夜校,英秀上午校,幼雅區,望堂孽校 一,大婆學校,大篙a聖光堂學校,元朗堂

WAH KIU YAT PO

生質名

蛮界計九 述召十小五十 用八共六學八九生于尤

校十名一八名:

製

用該校 七慈十萍全。雅干九中千校

足尾政府駅校

A 莫九百四十六元...

會津貼齊用於八十七 中學問,問

茶

NEKUR (E)

支持强大,並顯示談港獨奇然在港

「會倒狁穿其業而妙用 套斉的進步

校糕

,將心

日八月一十年七六九一层公年六十五國民中

̇會教督基華中

要需會社應適 展發育教重特

家一十學中家一卅學小有辦 家入小中成完年三建興劃計

(1) A reduction involving a loss of oxygen:

The reduction of cupric oxide to metallic

copper using hydrogen as the reducing agent. Equation: CuO •

H2

* Cu + H2O

(11) An oxidation involving a change in valency of an)

i element:

The oxidation of ferrous chloride to ferric chloride using chlorine as the oxidising agent,

Equation:

2F6C2, + C1, * 2FeCl3

(111) An oxidation involving a loss of hydrogen:

The oxidation of hydrochloric acid to chlorine using manganese dioxide as the oxidising agent. Equation: 4H01 → MnO2 MnCl2 + 2H2O + ca2t

(iv) A reduction involving a loss of a non-metallic

element other than oxygen:

1968

英文科

題額習書舖

TENSES

何玉柱・

II. Generally speaking, tenses tell us the time of the action or state expressed by the verb. Let us put tenses in indicative mood into four catagories and discuss them one by one: Simple tenses, which include simple pre- sent, simple past and simple future, indi-

Or, we may cate the time of the action.

1.

say, they express facts taking place at different times. Here are some examples: 2. He is healthy because he goes to bed

early and rises early. (now)

b.

He broke the dish yesterday.

C.

lle will have an examination to take

S/

The reduction of ferric chloride to ferrous- chloride using hydrogen sulphide as the reducin agent

• 2HC1 +

2FeCl2 + H2S - 2FeCl

2. When mercuric oxide is. heated strongly in a long

hard-glass test-tube, it first of all changes colour from red to black. The black mass gradually becomes smaller in volume, but, at the same time, a silver- like layer will be formed at the cooler parts of the tube. When a glowing splint is placed at the mouth of the test tube, it will be rekindled. If the heating is continued for a sufficient length of time, the black mass will disappear completely. Small globules of a silver-coloured liquid. (mercury) will run down the sides of the test-tube, if the test-tube is gently shaken.

Equation:

24g02Hg 02

+

3. An oxidising agent is one which is capable of causing

substances to be oxidised and is theref ble

(a) to impart to them oxygen, chlorine, ectronegative radicals, etc., (b) to remove hydrogen, metal or electropositive radicals from them, or (c) to remot electrons from the

Hydrogen

(ii) Bed lead

Chlorines

Reducing agent

(1)

Oddising agent

(iii)

Oxidising agent

(iv) Carbon monoxide

teducing agen

(1) When hydrogen is passed over red-hot cupric oxide

the uxide is reduced to

CuD H2 Cut metallic copper.

When concentrated nyarochloric acid is added

red lead, the red lead will oxidise the nydrochloric acid to chlorine,

8HC1 P5303FbC12

C12• WH2O

111) When chlorine is passed into an aqueous

solution of ferrous chloride #pale green solution), the ferrous chloride is oxidised to ferric chloride (a light brown solution).

¿FeCl2 + Cl2 • 2FeCl3

(iv) When carbon monoxide is passed over red-hot

cupric oxide, the oxide is reduced to metallis copper

a) First carry out a test to des if the subatanes is.

an oxidising agent.

Heat a little of the substance with concentrated hydrochloric acid. If the substance is an oxidising agent, chlorine will be evolved which will turn staron paper dipped in potassium iodid golution blue,

UG

from

oxidising #gent)

01

lodine turns starchi blue in colour)

(b) If the substance 19 not an oxidising agent,

out a test to see if it is a reducing agent, Warm a little of the substance with a small quantity of concentrated nitric acid. If a large volume of brown nitrogen dioxide is evolved, the substance le a

reducing agent,

2HNO3 - 0 2NO2

2K010

2(39435.5+48)

(given to

the reducing"

agent)

2K 01

Heat

3x32

245 m

96 20.

(22,413 litres at N.T.E)

Volume of oxygen, obtained at 17°C and 765 mm, pressure,

265 0.0.

tomorrow.

Usually there is an adverb or adverbial phrase or clause to show the time, unless it is an action that always takes place as a habit or is always true. Let us look

tell

at a. again: "He is healthy" tells us his present state, we use present tense "he goes to bed early and rises early us what he usually does. Going early and rising early are his habits.

Perfect tenses generally express the. Completion but not the time of actions.

He has done his duty.

C.

He had had his share or rood before She started to have hers

The building of the school will have been comp

November next year.

I'd take etely to

from

expresa the resu tences:

Sect tenses separ

des express-

seg

tion

In this etion was

the result

is different fuse simple past e action, not

following sen-

(1) He bought a car two years ago, (11) He has bought a car.

3.

pletion

by now, but past perfect tense

must not be used alone in a single sen--]

tence without an adverb to show a comTM arison.

(1) He has gone.--correct

(ii) · He had gone.--incorrect.

But (iii) It had occurred many times;

yesterday. is correct as it means it

had occurred many times before vestër- day ended.

111) Future perfect tense. 'snows the comës

pletion of an action by a future time e.. In July next year, we shall have

vaken the school certificate exam., Continuous tenses emphasize the progresa, ing of action at a certain time.

a.

b.

C.

She is teaching composition now,

He was singing loudly when his teacп87. came.

He will be going to school tomorrowį morning 7:30.

a. means the action of teaching is going un. It is different from "She teaches composi- tion.", as the latter tells us the fact what she teaches, she may be at the time doing something else while a. tells us what she is actually doing; she may teach other sub- jects.

5. also differs from "He sang when nis tea- cher came." The latter tells us when he sang, while the former, what he was doing, singing had begun before his teacher came and it was still progressing when the tea- cher came.

c. means at 7:30 tomorrow morning he will be on his way to school. If you say "He will go to school tomorrow morning 7:30. you mean he starts going at that time. 4. Ferfect continuous tenses are used only when you want to give others a deeper in- pression of an action's having been done"/ through a period of time and still being performed. Hence, it is all right to use perfect tenses in place of perfect contin- uous, I'll pick out present perfect and present perfect continuous tenses to dis- CUBS.

a. It nas rained for a monta. b.

It has been raining for a month. When you write a sentence like a.. you are not considering whether it may still rain

à, but by b., you tell us it is still rain ing and may rain for a longer time. "Practice makes perfect.". Let us practise. Ing the above tenses correctly.

EXERCISE ONE ‹

BRARI

In (1), whether he still has the car out of the question; we only want to know the fact about what he did two ye ago while in (ii), we do not care when he bought the car, we only know that he still has the car--this is the result of the action buying. Therefore, when you face a sentence or a paragraph to decide what tense to use,

consider whe- ther the fact or the result is to be know

11) Past perfect tense expresses the com-

pletion of an action before a past time, or a past action. From example b. we understand that when the girl started to eat, the boy had nothing to eat because he had eaten his before the girl ever began. However, we have no idea when the boy ate his food.

This past perfect tense is unlike pre- {sent perfect because we can use present

perfect tense alone is a sentence with-3

out

Ouf, any adverb to show time as we are

thinking of the result of_the_com-

Voluma of this orgen at N.T.P.

760 275

X 765 * 290 × 0.265 litra Thus weight of potassium chlorate an

required to produce)

* 2452m.'

this volume of oxygen

760x27300265

322

Weight of mixture of potassium chlorate and manganese!

dioxide 1.330 gms.

of potassium chlorate in the mixture

760x273x0.265x245 x 100

68.2

90x22.4x3x1.330

show that manganese dioxide serves as a catalyst in this reaction

(a) Heat (gently) some manganese dioxide by itself

a hard-glass test tube, no gas will be evolved. Manganese dioxide does not give off oxygen at low temperatures,

(b) weigh the manganese dioxide before it is mixed with

potassium chlorate. At the end of the experiment,

When a 11

Lower--Fut_the_verbe in their proper

tenses.

The business (1) De

letter got there.

Isettled when the

(2) you prepare the lessons_that_the] teacher assigned'

They (^) take)dinner in the next roomi now.

14.* I (5) understand — what you say.

5. No aeroplanes (65) fly to Japan tomorron Higher--In the following passage, put

1.

the verbs in their proper tensest

One night, a few days after my brother (1) go abroad..I (2) eat my dinner and

(3)lle in bed fast asleep, when I (4) be suddenly awakened by my mother. She (5) call out, "Get up, Rose, little Tom, (6)be sick, go quickly to fetch the doc- tor! Before I (7) can think, she (8) pu the overcoat on me. She then (9 run out leaving me the order that I should put on

I (10) To my shoes as soon as possible. out as if in a dream, feeling very afraid, as I (11)be out at night alone.

Mother (12) wait at the door. Sne take out my bicycle and (14) push me the total darkness before. I

can ever) express my unwillingness and fear.

potassium chloride, and undecomposeu prcassiuli chlorate (if any) will dissolve. Filter off the solution and the insoluble manganese dioxide is left behind in the filter, Rinse, dry and weigh the manganese dioxide. It will be found that the weight of manganese dioxide is the same as that used at the beginning of the experiment.

Questions for next weer (3)

1. Outline the manufacture of oxygen from air. How, and}

under what conditions, does oxygen react with

(s) Sulphur dioxide, (b) carbon monoxide, (0) nitric oxide?

2. State what you understand by the terms

(a) acidic oxide; (b) basic oxide; (c) amphoteric oxide. How would you show that (a) sulphur dioxide is an acidis oxide; (b) magnesium oxide in a basic oxides (o) zinc oxide is an amphoteric oxide?

By reference to the relative case of the formation and stability of their oxides, arrange the following metals in their correct order in the electrochemical aeries:" magnesium, copper, lead, mercury, zine, iron, sodium, potassium, calcium,

Mention three types of reaction whereby hydrogen is roduced, Give one azamysle de