1965-05-22 — Page 20

六、

日二十月五年五六九一群公年四十五國民辉中

T弍題預習專欄

四第張五第

B二十月四年巳乙解室

WAH KIU YAT PO

一九六五年度中文中學會考

華僑教育

物理科

(廿四)

英中會考化學科答案

Answers for H.K.E.S.C.E.71955. In Chemistr

1. (a) Name four substances which liberate oxygen on heating

1. potassium chlorate

iii. mercuric oxide.

11. potassium nitrato.

ive red Head:

(b) Give equations to show what happens whens

carbon dioxide is absorbed in caustic soda.

d zinc oxide is treated with dilute sulphuric acid,

iii. aluminium oxide is treated with caustic potash.

iv. calcium oxide reacts with water.

v. sulphur dioxide is reduced by hydrogen sulphide.

Answers:

4. CO2 + 2NaOH = NázCOg + H2O

Li ZnO + H2SOj .Zn30% +$20

111. A120, 2KOH = 2XA102 + H2O

iv. 502 + 2H25 * 2820 ** 351.

2. write equations for the reactions between the following pRING

of substances, and state whether the substances underlined havë

been oxidised or reduced.

1. Hydrogen and chlorine.

iii. steam and red hot iron.

Answere: 1. 2 =

+ CL2 11. Nf3 + 301

51. AMORIS end chlorine,

iv. ferrous chloride and chlorine. reduted)

6NHACI + N2 【 oxidised ) Fe30% EX reduced)

iv. 2FeCl2 + 012→ 2F6G14

3. A colourless, mobile Liquid is alleged to as wafer. Nans the TestD

you would make to ascertain that it

(a) contains water..

(b) contains nethink but water.

Answerst (a) It will turn white annyarena Copper sulphate King.

(b) 1) Its density at 4°C. ds.1 gram per.c

(ii) Its freezing point j50°C

state briefly how you would obtain samples of

(a) normal sodium sulphate,

(b) sodium BiSniphate,

from solutions of N-sodium hydroxide and N-gulnhizie scia.

【a) Sodium sulphate:

Add equal volumes of the two solutions to each other, the

resulting solution will contain sodium sulphate which may be

obtained in the solid state from the solution by crystallisation.

(b) sodiom bisulphates..

To a given volume of N-sodium hydrozide, add twice the V9IUDIJ

of N-sulphuric acid. The solution will now contain sodium hydrogen sulphate which may also be obtained in the solid stata from the solution by crystallisation.

5. Name. in order, the elements whose atonte numbers range feat 1 to 6.

1. Hydrogen

Lv. beryllium

11, helium.

boron

praw diagrams of the shell (2.0. örb hydrogen, carbon, sodium, calcium,

carbon

stracture or atoms of

Hydrog

Carbon:

陳樹邦 - 編者按:此稿原應於本週四升出,是日籍作者有事,未能執筆,故於今日

·福

物理科試題預習

(Wheatstone bridge) 2.

可測出一未知電阻數值 建諗時好像陳 依有图之形式裝

、、數值之電阻

量图中投1馬

的

電阻的為已知 G与 - 微量電流 E亏電池.

當電路接通时,希

有電流流向口 或由D流向則G上

的指针即行擺動中學時調節電阻和 在存或有上的電阻,使微量電流計 G上指针约费数与零即表示♀電流由 B. 洗白 6

當BD線上點電流时,即B美的電位与D $ € 13 #13 Up VaR. VAD VAC - Vic

流必再由 流向。

再由口流 同理,由A流向Di笔流

芳

I

代入即得

則未知龟阻之數值可由

一式中求之

普通宴验室中做惠斯乔電橋電睑時喜 装量多採用滑線電橋而不用電阻箱因 滑線電橋較易調節之投

固是一電阻捧(或均小的電阻绿) Ac 之間是可移動的接觸键即成一 滑線電播電拾好,将未知電阻量數。 因足数値的電阻 我移動滑你上的接觸鍵,使微量電流 計上指針的工讀數嗎零然後纍出AD為 DC = te z bik l1 BJ DAP & DC M 的電阻356是成正比則依 惠斯太電橋樣之原理,未知電組:数值

la

物理科假想試卷

~

(skide were Bridge) 测是未知電X,已知當電輪平衡時 導線被滑動接頭所分的西政各長 40及60厘米,電阻箱車打64厘米導線

1 的一方若其上所示的電阻為3歐 姆 求x的值

(二)(Q)試述電流所生的研效应(Magnetic

effect of current) a q t l U 試建電鈴;構造及厚埋

(2) cas in ef 12 13 8 (Faraday)

定律

(6)欲将-面板為250平方厘米的金书

電鍍上銅若所用電流

7154吃時則需若干分鐘始能鍍

0:01厘米厚的銅,

光知

(七知 铜的電化當量与0.0003295/0

4/12 15 8.93)

38姆的電阻線圈,投入Jom 治原 米的水内通55岁坛的電流設水 原來的溫度為10°C时通電10分鐘後 水的强度盘马君干後·

1 £ 12214 ( Lenz Low) (b)试述支厨器(Themefineon)的構造

及原理

Excalienatione

6. (a) erines

Answers

1. electrolyte“,

Galer

MILF WOAR Acid,

LI CATHOGS,

1. An electrolyte is a compound whion when molten

or when dissolved in a suitable solvent (usually water) will conduct an electris current. 0.g. common salt

11. The electrode connected to the negative terminal

of the battery da called the cathode

iii. a weak acid is one which when dissolved in water.

is only partially ionised, and is as a result B poor conductor of electricity.

.. acetic acid.

[b] The same current is passed for the same time during the

electrolytes of. a solution of a silver salt and acidulated water respectivaly. In the former, a deposit of 2.16 yms of silver was produced; in the latter there was an evolution of 224 ces, of hydrogen at N.T.P. Calculate the equivalent of silver (OR the atomic weight of silver), and exciein tha used in the calculation.

Calculations- SIIver deposited

2167

Hydrogen evolved

224 do at H.T.P.

ov 22.4 litrén]-

216 gua

1.08. gue

Equivalent inigi DigiLTE2 = 108

The calculation is based on

Fevaday's 2nd Law of fleetobysis which states that

shop the sake quantity of electricity is passed through a number of electrolytes, the weights of the various

elements Liberated and propertional to their chemicato

of all races at N.T.P.

1. normal solution.

11. molar solutjen.

A normal solution is one which contains one gram equivalent (ice, the equivalent weight in grams) in one litre of: solution.

11. A molar solution is one which contains one gram molecule (1.8. the molecular weight in grams) in one litre of. solution.

(b). How many grams of sulphuric acid, acetic acid (CH3COOH), or

sodium hydroxide are contained respectively ins

2

litrs of 0.5M sulphuric acid.. 11 1 litrs of decimolar

acetic acid.

iii 100 cos. of ZN sodium hydroxide – iv | litre 4/2 sulphuric

acid.

Cálculations:

32

Equivalent weight of Hg804 **49 Weight of sulphuric acid in

litre of 0.5N ácid 49.x

¥ 12.2500元

11. CH3COOK 12 + 3 + 12 + 16 + 16 + 1.

1 gram molecule of CH COOF - DO gain.

Weight of acetic mold in 1 litre of decimolar acid

- 60 - 10 gas,

Lii. •NaOH/23+16+3

❤40

6 gada.

Equivalent weight. of N1015 - 40.

Weight of sodium hydroxide in 100 0.9% of 20 solution

-40 % 2-10gms.

19. molecular WBIENT OF H-50, - • 98

Feit of sulphuris moid in 2 litre H/2 act

24.05.

8. That Is the effect or prolangea exponsure of a clean Iron surface

11 humid air, 511 rain water,

to

dry ass

y pure water. £.e. containing no dissolved substance.

Answers?:-1-NO SITOLU

IL-TRE FTON -Fusta

Lli The iron rusts

Lv No effect

What conclusion do you drax zom the results of these experimentat

Answerá: Both air and moisture must be present

for iron to rust,"

9. Rame the metate present in the alloys belows

brass..

迷

Bolder

Anst: Copper and zinc

Ans: Lead and tin

What special properties of the alloy known as "type metal” make ID especially suitable for use in the printing industry?

Answers: The Lead(70%)melts ieasily and can therefore be cast

cheaply; the antimony(20%)makes the alloy hard; the tim (10%) makes the alloy flow more freely into the mould. in addition, the alloy expands on cooling, making it especially useful for casting twpe..

10, made the series represented by the general formulaes

ames L. Fatty aciwa

11V Alcohols

What is meant by (a) unsaturated compound, (b) additian scompounar Arpt (a) A daturated compound is one in which the valencies of

all the carbon atoms are satisfied. For example, methane. C

(b) `An unsaturated compound as one in which the carbon

valencies remain unsatisfied, giving rise to double and triple bonds:

a.g. ethylene, C2H)

An addition compounù 19 obtained when certain atoms or groups of atoms add themselveson to the unsaturated carbon atomein an unsaturated hydrocarbon. e.g. chlorine peadts with ethylene (an unsaturated hydrocarbon) to for the addition compound ethylene dichloride,

(98

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