第五集
CITY HAL
中文中學會考試題預習專欄
敦學科
(廿三)
第廿二次預習試題解答:
·喬仲强。
(1)(a)將一個4吋x2李时×号时的長方体,分割成相同之最大 正方体,間说)正方体每边長?(i)每個正方体立体?(
正方体若干個?
(解)此長方体之三度為4吋,H.CE(最大公約數)意 此即為好求正方体每边長吋數,故体積((立方吋) *** (÷) × (≈£÷†)× (/÷÷)=24×15×10=36001 答:正方体边去时,体積為25立方吋,共有正方体3600個、 忍)某人的收入增加20%,但其入息稅則由每鎊4先令增35 先令問此人之纯收入增加之百分率若干?
(解)每鎊4光令之稅率為20%,每鎊5先令之税率骂 嘉=25%設此人原有收入為100%,則繳稅後凈得鸢 100%×(1-20%)=80%;增加收入後,其收入120%镦税 後凈得為 120%x(1-25%)=90%。
該收入增加後,其纯收入為原来纯收入之號112套90 即增加.12元% (答)
(註)本題不可以 90%-80%—10%為答案,因此百分率係原来 未缴税前之收入(非纯收入)為“母數(100%)故也。
(2){a} 一空心鉄管,其內面直径2号呎,其重量典等長而直徑為 湯之鉄柱相等,問此铁管之厚為若干時?(準確至小數两位) (解)因→32吋,13呎=16吋,
談鉄管厚吋,則其妹面半篤1648吋,長度為见吋,則 ( == π { ( 1b + x)2 = 1 6 *] × & ે‡‡ 4‡ =π × 8 × £ £t.
π [ ( 16+ x)2=162] × l = + x 82 x 7.
(16+ x)*—16* ---- §
16+%=184 -₤320-
=17.89(查平方根
x=1.89
答:铁管 1.89吋
湯)有密度為每立方厘米0.6克及1.1克的兩種液体,混合後密度 為每立方厘米0.75克,求其混合比
(解)設此两種液体各用x,y立方厘米,則天重0.6x+1.14元
依題意
0.6x+1.19=0.75 (x+Y)
0.35y=0.15x
0.35
ONS
答:其混合比為7:3.
(註)本題亦可依混合比舊損蓋成反比之方法求出
(3)64x+ax+82-40x416為完全方式,試求af之值
(解)其平方為x之二次三項式,且其首項為x(但未項可能為 ±4)現假設平方根為200+px+g/其中48文字當數
4x2+ax38x~40x+16=(2x2+px+8),
— 4x2 + 4px + 48 px + 2 p q x + q z
“比較两边係數?a=p
*(2)
AH KIU
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AT PO
明起一連三晚在大會堂演出
浸會學院劇社
演 橋頭遠眺
▶欄專習預題試
化學科 (
J
九
時自由題會,七情六』七。各唆友知識
一饭店。席金-母位十健雅定席苫。〔珧〕
CHEMISTRY (23)
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| 五日假六國店舉行 榮生辦辦館,電話: 「八大會,定期木月十弈,小閣患嘅街二號 中學校友會本年度 獎。售票處-蹴亦 〔舂訊〕金文樂,二元。餘興:幸運抽 十五日般六國酒店舉行 堅-大道店三九號
上 定期同人大會
英
•
王錦釗 •
1.1.An intimate mixture of amimandum chloride and slaked
lime is put into a round-bottomed flask, and the. apparatus is set up as shown in the diagram.
JAMNUM CHLORIDE
To DAY the
When the-flask is heated gently, ammohia gas is given off. The gas is dried by passing it through a drying tower containing calcium oxide as a drying agent. The ls then dollected in gas jars by upward delivery; gas.
Ca(OH)2 + 2NHLCY CaCl2 + 2H2O + 2NH3↑
slaked Time
ammonium chloride
(1) when a gas jar
jar of chlorine chloride are: -action of aEM
8NH= +-3C+
Ammonia
=
ammonia
da is inverted over a gas
cite fumes of ammonium
result of the reducing.
期 金文泰校友會
Q.2(87
日五月四年七六九一层公年六十五國民中
你先·柏怨,符合
元面板老力,本稻越。州
A
,仍年後宣行 師資 加
使費二期大校。院試圖
人數仍擠
(特選} 本年度]餘人,其中三千
·今年共達七千八百餘人
|投考師範|
•今年三開篮學
[本年度報考三批|性,要有超卓的这
四季校青年,才可望有取錄機 是引考試有高飛的胡
• (E)
Test\ (i)Substanceyx
s heated' gently
(ii)Solution or:
x + hydrom chloric acid.
*barium
chloride
solution
Observation
A gas is evolved which turns damp litmus blue/
A white pPLE 19 faman
Hence X is ammonium sulphate]
擠範
"Inference
The gas evolved Is Ammonia since it is
the only common alkline gas.
x is therefore an ammonium salt
The precipitate 19 harium sulphate, which is insoluble)
in hydrochloric acid
Ba
穿
** 504 Ba304
* is therefore at
sulphate
B.2(b)The common drying agents used. in the laboratory are:
CONR
(1) Concentrated sulphuric acid,
(ii) fused calcium chloride ~
(iii) quicklime,
Yiv) phosphorus pentoxide;
(v) ailica gel.
Two ways in which gases" are brought into contact
with the drying material are:
(a) by bubbling the gas through the drying material:
if it is a liquid such as sulphuric acid; . (b) by passing the gas through the drying material,
: contained in a suitable piece of apparatus,
such as a U-tube, if it is a solid such as fused calcium chloride.
NET
GAS
DRY
ÚAS
FUSED
由(4) 得
2pg=-40
2016
代入(3)得本三
-20
5208209.
=4,代入门(2)得
-20 b=41 £ a=20, b=9
(注):其方根萬+(20=50+(4)
(4) 解方程式
+A+&O
(26) £54 ali+ bx)+ f (i+ax) + (a+b) (1+ ax) (1+ bx)
£3 a+abx+b+ab x+ (a+b)+ (a+b) (bx+ax)+(a+b) ab x'= 0
ablars) x2+ { (a+b)+ 2a8]x+2(a+b);
分解 (abx+(a+b)][(a+b)x+2]
=味或
因此两值俱不能使分母為零故為真根。
(5)卷
試証:
at aft
(証)由己設式依反比得其
~ 2 + ( 4 ) = a+b
a+ab+b
(13) when an-aqued
a soluti on of . precipitate of
honia is added to
a brown gelatinous Pride is formed, which
ds insolble in excessor ammonia.
'`3NHOH_A:FeCl>
HONGKONG
Q. E. D..
3NH, C1 + Fe(OH) zł)
COPPARIES
Merric
hydroxide
(111) When an aqueous solution or ammonia is added "drop
by drop to copper sulphate solution contained in
a test-tube, at first a light blue grecipitata sopper hydroxide is formed:
„2NH2OH + CuSO1 = (NHL),30,*+ Cu(OH
gopper.
'If the ammonia Ls added until It is in excess, the precipitate will thesolve and a beautiful deep blu solution of a complex copper salt, cuprammoniuy sulphate, (Cu•4NHz) SOд H0 is formed
'vJWhen a gasjar of ammonia is inverted over a gas
Jar of hydrogen chloride dense white fumes of ammonium chloride are formed as a result of
chemical.combination between the two gases.
NH + HCl = -NH/Cl Thydrogen
chloride..
Suitable Drying Material,
H2S
Fused calcium chloride
Cl2
Fused calcium chloride'a.
cone. sulphuric acid)
NH3
Quicklime
ICO.
Fused calcium chloride.or] conc. sulphuric acid.
Questions?For Next Week!(24)
Q.1.How do the following behave towards,
(a) a solution of ammonium nitrite: (b) Solid ammonium sulphate: (c)
Solid ammonium dd chromate1.
[Chefactionfofi heari
2.2. (a) A salt M on being neated with caustic sodalgave) off a gas which turned red litmus blue.i
(b) Addition of silver nitrate solution to a solution]
of Min water gave a white, precipitate whichiwâg insoluble in nitric acid.
What is M7 Explain and give equational forīthe
· reactions
Q.3.Give lead nitrate crystals.describe now you could
obtain from t them:
(a) oxygen; (b) dinitrogen tetroxide: c/leadisulph ate; (d) metallic lead.
Describe the reactions whicn.take, place between nitrogen dioxide and (1) water, (ii), moist, sulphuri dioxide.
(註)本題亦可依下
依更比得哦
(6)描绘,y=(x+1)(x-4)图解(X取值由-2至+4),並利用之
以解 33x8-48+4=0(答案須準確至小數後一位)
(解)先製成下表:
14249
y== x(x+1)(x-4)
3. 42
012-24-24|| 012220
然後選擇適當之單位(维横軸均為一吋表一單位)描出各卖 依次連结之得·吉x(x+1)(x-4)曲线,因製表時當==-1及。
時,你有相同之值,故需再設...............
因绘曲线為5y=x338 15g+4=0.故於同一图中加终 即為求之根
之代入求解方程式得 (4)設0萬△ABC内任意点遇口作 DGHABEHI BC, FKII CA 若之直线,其交奌之横坐
EHFK
AB AC CA
由图中得 x=1.5 0.7或3.8(答)
(5)設如右下图: P笃△ABC 外接园之AB弧、 (註)由根與係數關係,可知方程式三根和*數之变号好上任意点 PELAB PF1BC(F在BC线上) 此值可利用之算
PF之延线交 ABC园於G. 試証 - EFI AG.
D
4£=== X(X+1)(x-4).
̇第十三次預習試題 {1) AB马d园直径,CD典AB交於P
過P作AB文垂线交ACAD(或其延线). 拎E及F試証CE DF共园
|2) 0為△ABC 外接园园心, AO延线!
交 BC柊KAHL BC交BC於H
"AH BH-CH...
AKL
BK CK
(3)以沈:△ABC之 三边向形外作諸 正方 ABDE. BCFG 及 ACHK. 则者三角形,
\AEK_BDG=CFH ¥IŤ (LBACŹ11r
H
(6) ABCD為任意四边形一直线
AB BC CD 及DA (或其延线)各於E
AE
LEB
DH GDWHAS