1971-05-13 — Page 15

育教僑華頁三第張四第二日九十月四年

AH KIU YAT PO

報日僑華

香僑

T

wwwwww

1971 英文中學會考試題預習專欄

新光出版社主編 SUNLIGHT PRESS

化學科

CHEMISTRY

LESSON THENTY-SIX

FINAL TEST

CONVENTIONAL SECTION (Continued

(a) that is meant by: (1) water of crystallisation,

(ii) hardness of water?

(b) Give the names and formulae of three salts containing.

water of crystallisation..

(a) If the formula of lipsom salts is MgSO x Hㄣd and the

percentage of water is 51.22, what is the value of x?

(8 = 1, 0 - 16, Mg - 24, S - 32.)

State the law of multiple proportions and describe how the truth of this law could be illustrated in the laboratory in a particular case.

(b) 5.60 gm of a metal combine with chlorine to form 16.25

gn of a chloride which, on reduction, gave 12.70 gm of another chloride of the metal. Show that these resulta illustrate the above law.

(a) State (i Gay Lussacts Law, (in) Avogadro's hypothesit

(law)

Calculate the volume of carbon dioxide, measured at

20°C and 75 na pressure, which would be obtained by

the action of excess dilute hydrochloric acid on 10.00 gm.of calcium. carbonate.

If the Farbon dioxide so obtained was passed through large quan ity of red-hot carbon, what gas would be formed, and what would be its volume measured at 20°C and 750 mm pressurefe

(C = 12, 0 - 10, Ca = 40. One gran-molecule of a gas occupies 22.4 litres at M.PA

Define the: "equivalent weight" of an element. D, E, and Fare three oxides of a metal as

(1) 200 gm-of D contained 40.am of oxygen..

(11)18 gm of when completely reduced in a stream of

hydrogen, left a residue of 16.W

(iii)When F wasconverted to a solution of the correspond

-ing neutral salt and 6.5 gh"of eine was added 6.4

gm of metal A was deposited.

Calculate the equivalent weight of A in each oxide. If the formula of Dix AD, what are the formulae of Cano FI (Equivalent weight of zinna (22.5)

(a) Explain'what is meant by: (1)Jion, (ii) electrolys

(iii) anode.

(b) Describe and explain how eledtrolysis. may.be used

(1) to purify copper, (11) to produce sodium hydroxide on a large scale.

(a) Describe an experiment by which you could deter

with reasonable accuracy the equivalent weight of either zinc or magnesium.

(b) 3.36. gm of ametal on oxidation gave 4.80 am of meta:

oxide.

During electrolysis a certai

caused ti osition of 8.40 liberation of 0.30 gm of hydrogen.

of electricity:

fa same metal and

Calculate the equivalent weight: indicated in each case and explain the results obtained,

What is a reducing agent?.

Describe ONE reaction for each of the followingu which shows that the substance can act as a reduczo agentr

(i) hydrogen, (11) ammonia, (iii) hydrogen chloride, (iv) hydrogen sulphide, (v) aulphur dioride.

(a) Describe:in detail the laboratory, prepareation andy

collection of dry ammonia.

Ch) How is ammonia converted into (3) ammonium sulphate

(1) nitric acid?.

(c) What is the reaction of ammonia with (1) chlorine,

(ii) ferric chloride solutionT

(a) Describe how hydrogen sulphide is usually, prepared ana

collected in the laboratory. State its main physical properties.

(b) Describe the reactions which take place when hydrogen

sulphide is passed through aqueous solutions of (i) copper sulphate, (ii) sulphur dioxide, (iii) Terrac chloride.

Descrita one method for the preparation and collection of a reasonably pure sample of sulphur dioxide in the Laboratory.

(b) State the conditions under which sulphur dioxide reacta with (i) litmus, (ii) lead dioxide, (iii) magnesium, (iv) chlorine, and explain and describe the reactions

which occur

13.(a) Describe in detail the, laboratory preparation of a

specimen of nitric acid. Outline how you could obtâl from your specimen (1) nitric oaide, (ii) ammonium nitrate,' (iii) sodium nitrate.

(b) Give one chemical test by which you coula distinguish between dilute nitric acid and dilute avdrochlori

I. (a) Give a brief account of the manufacture of sulphuria

acil, starting from sulphur.

(b) Desr ribe the reactions of sulphuric acid with (i)

sod un nitrate, (ii) iron, (iii) crystalline copper sul, hate, giving the relevant equations and indicatin in rach case the appropriate temperature and con- centration of the acid.

15. (a) defie (1) an element, (ii) a compound.

芭

08

How would you show experimentally (i) that air is aizture, (11) that both air and water are necessary for the rusting of iron? (iii) that water is an acide of hydrogen?

How would you prepare in the laboratory a diluta solution of hydrogen peroxide?.

(b) Describe what takes place when hydrogen peroxide is

added to (1) manganese dioxide, (ii) lead sulphide, (111) acidified potassium permanganate solution, Give equations for the reactions (1) and (ii)

·中小組學生徵文

BA

利用郊外旅行-

賓知

B:寫日記的好處

比一碗雄。因此,正家育在各方面

嚴,另抵對地址及生帶轉進。 林安五十元,明威四十元,全車三十,傣路若干,希各䴙十元, 辦法·斯迎至湾及以下同鞑終加,八小路五六然说亦可取退一千五百,五月廿二日

美初級機制造, 蓋的假畫區課,其中不少一

| 愅否有專門的需要。 一等。而在治造會提報之前,此好亦已在者世 |一個永女性的越快,在車計劃號工来跳等

自由畫比賽

·幼稚園組 H丽湖图:B我最喜低的小帕物·C我們世行去D我的家庭成自由變 我

·初級組 吉恩谢 - B渺的夏日生活缪R寫的工作, D嘢就没过同:可自由设 (ETHER)

B虓己我愛小野物,D自由平 的戲

即日起软件,至五月廿二日上敵,以聽爲證,難不婭.6, 所有各組貓次班,應戴者號另紙鶴訊地址、仡名及班後,以便所你。 一批尺度身勿小干十五科版十一时,勿大于二十四計四十五吋... 西第四十元,季出世元。熱門各罪多業務共一百名以上,薄

四期星日三十月五年一七九一曆公年十六國民中

及及

港府檢討教育發展近況

小學普及教育已達成目標 繼將施行免費強迫教育

將學教

-

計達

專

科在

狩入歷的小宝在站上十六节三百九十七名 活,直调价小學族奇的減。一方正,年內小濕度位上關的學生,現世界至11千九百九十名。中文大 ◎年的雾迷」!小册子中指出圈多年來,一元,作增望設為常開銷的費用,安浩大韩

雄、福建的另一所工班學校都伴入體所新

發實強!

中教

學育

日卅、九廿院書西中 會晚娛文模規大

人兙発売受接仍現試學入行盛日五十

店綸界知名人士。

月的至变小學高骨可。父母的人亦有染 大打進步。被价也将之正本西裤殊的阿树上的限

·生交唔晚會,使學生在

活動道

創四子

華僑日報 四十六週年舉辦

創刊紀念

湏壽山ㄤ至一夜,小 用一字方丽有的,變中

【助惠政賀。此,工作將分也強,希望第一 正北橅在心而製的對「壓品,少演得之年的

下一個主要登體,於推行山烈心此育,

的斯政策,到一九六年彜榮學位十蓏 世至三年版的瓷助燃位,但行寺助中總教臂 政府補助學校之內,已有六萬二千億由中一年 力征壓生在適當的棋立學校就讀。目雲及 太,陶缓由疾榨利學校提供,甚食可以代交學費 立和政府補助學 直接拉供,亦可以粉予輔助方

·直洲樂取教育北宫止。然學位可由官 「六歲的水壓生,在百分之十,十得安助

發啓者:六月五日落僑日報何符四十六週年,雲稱念夢,博大算解,桅印特刊,同時

·乃無生持影比安茲將純攻及供顯日及難出刊如下,各校图斯與參加, 舉行公開,工友,茲女應大謀,中學,中小,幼稚園區生微文及自由爽,然亞書公開

學生兒童徵文徵爾比賽啓事

大專學生徵文 ).

B.A

BA

A 學生運動面面观

B.深入社会正確認識社會

佢,到附宫,另坻諧地址及無生醫院,

·辦法?野们大旗生(UPPER SIX亦可)塔,字数很兰予,五月坎11日截

二軍成金三百元,返眾一百五十元,季第一百元,另學優良者半個,如各四十

A 對香港勤節目的建

高中組學生徵文.

信,男無附地址及麟生證號碼。,

普及康樂活動鼓勵青少年參加..

概..幂百五十元,軍一百元,實五十元,優麗的花,號為各&三千元!

1971 英文中學會考試題預習專欄

新光出版社主編, SUNLIGHT PRESS

物理科

HYSICS

LESSON TWIENTY-NINE

ANSWERS TO REVISION TEST CONVENTIONAL SECTION

See 12 (e)

(b)

(二十九)

With an Illuminated object in front of aconvex: lens, the image. I is obtained on the screen. The convex mirror is placed between 1 and the lens until, the reflected image falls on the object. This happenis when the raye "Incident on the mirror are perpendicular to the mirror qurface so the ways will be reflected along their original incident ray. This means I is centre- of curvature of the mirror, sa M Ij (c) (1)

By using lens equation

-8 cm

--- (Real is positive).

Image being 8.cm from the lens and is on the same side sa the object. The image so formed is virtual, (ii)

By applying lens equation - + - - -

13

cm (the image

spending wis

lgular col

soft van care

(b) When current is passed through the coil, equal, and opposte

forces acting on Ad and CD (by Flemine?s left hand rule) since the coil is in the magnetic field produced by mugnet. This constitutes a couple and the coil will be deflected. A point and spring are attached to the wire, so the angle. of deflection is indicated by the pointer. It has been found that the deflection depends on the magnitude of T current, So the instrument is used to muasure current. In order to have more sensitive galvanometer(i), a soft! iran core is mounted inside the apiland (is) the aurface of the magnet is made concave so as to make the magnetic. field radial and greater in magnitude. fili) The number of- turns in the colls 'should be more but not too jouch otherw wise the resistance of the galvanometer is increased con- siderably, (iv) The area of the coil should also be large,

名報生新级各

二百保生日按及收

*院

月下

(c) Since G and the 512 resistance is in

parallel, the equivalent

sistance

good

resistance in the circü

-200

I. Since

$2x20

4095, 40

amps.

Sensitivity means the current flowing per division; of deflectione.

*Sensitivity

(a) See 18 (a) (

B

罩

4095 50 amp. division"

0098 milliamm, ner division

Since when I Faraday of electricity is used, the weight deposited is the chemical equivalent and when 1 coulomb is used, the corresponding weight is the electrochemical equivalent z. Thus, consider 2 élementa A and B.

From Farada

Faraday: (Since £ -

coulomb im gonstant)

In the given problca, Tet A stands for A B. for Cu.

The currents through the voltameter are not the same. eince they are in parallel (ie, the same p.ds)

'nce the time t for each case is the same

2

B.

where R. and voltameters)

are resistances of the corresponding

0.6

•I (G+R +D} Reading on V IG

quivalent resistance of G and

The

*G+R+ H

and T:

án

Reading on

the readi

R.

case is the axis.

G

RA

Page 15Page 16