WAH KIU YAT PO
頁四第張三第日四初月五年子甲厩夏
衣比
五日在長會會所舉辦 有見及此,特別於六
一,現代新式的比色檢定 的高整成表礼堂之精
·投靠進人生乐性素優越 〔卷[ ]在香港 | 部份文化設施 製衣商會辦研討會 方法之威用亦漸受重魄
·端陽照常開放:助。
·評劉事各事表演之一
(4)5(B)
往熺端午閨公眾假期,月八日止,市民可在大 」
| 觑暪訂瘓現正開始至大
大會堂活紀念花園照
伯悯育館及香港體育館
展代土色方法之運用, 扃研討會,民主題後,博物館片李诚玉分館, 由十元至卅五元不等 香港藝學館、香港、索取訂票捆子上,各場
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Se
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人上,歡迎致電香港製 比色方法有興趣的各界 宙個比色核心系統。對 並提供會中示範的最新 衣業總商會查詢,該會
十度。在昨日二十四小時內,本港天文共錄 得三點二毫米雨
「雲,有客散驟雨及局部地區性狂風雷暴,並 預料日問短暫時間有陽光,最高氣溫約爲三
·本港今日天氣預測:吹和緩西南風,多
、+ 山西南向東北沿著華南海岸伸展。但
局部狂風雷暴
◎ 多雲零散驟雨
港天文台.
在低壓槽
1984
中學會考試題預習專欄
化學解答建議
明德出版社朱宏林提供資料
SUGGESTED SOLUTION TO
CHEMISTRY
(i) Zo(s)+2H* (aq)
Zn2*(aq) +2(5)
(ii) The set-up is shown
in the following diagram.
cork gas syringe.
small test-tube
gine granules hydrochloric acid
(iii) n(Zn) reacted
(iv)
-65.0
=0.0154 mol
According to the following equation.
Zn+2H
Imol
melting point.
(i) The presence of TEL
usually increases the
octane number.
This is to increase.
the anti-knocking
effect.
(ii) Pentane.
(iii) Yes. It is because
the octane number.. of a hydrocarbon increases with decreasing number of carbon atoms in the molecule. Lead compounds would be present in the car exhausted gases. The health hazard is lead poisoning.
(iv)
(ii)
He should remove the delivery tube from water first. This is to prevent the sucking back of water into the hot test. tube so, as to cause any cracking.
(1) Decolourization of
24
+H2
(2) 1
n(H) finally
obtained n(Zn)
reacted
0.0154 mol
final volume of gas
p.-24.0x0.0154
at r.
-0.369 am
-369 cm
(1) Same. It is because
the hydro-chloric acid used is of the same concentration in tests 1 and 2.
(2) It is faster in test
3 because. the concentration of
-hydrochloric acid used in test 3 is greater.
(v)
Vol. of
gas
evolved
Test
(ii)
Time (5).
A: iodine or bromine
(in solid state).
B: sodium chloride C: diamond
(1) B: it is ionic
bonding (2) C: it is covalent
bonding.
(iii)
(1) The constituent
particles in A are held together by the weak intermolecular forces while those in B by the strong electrostatic attractive forcés. Thus, B has a higher melting point. (2) The constituent
particles in Care joined together by the strong covalent bonds while those in A by the weak inter- molecular forces. Thus, C has a higher
bromine solution.
is an alkene such as ethene ..
(3) CH=CH2+Br2
報日僑華
日期星
日三月六年四八九一曆公年三十七國民華中 育敎聞港
一
.梅窩公共圖書館的
本港新聞
「至下午一時,
「下的其他公共圖書館, 包括流動書館在內,將
市政院文化署
開放時間則爲上午十時
福 週二接受報名 旅協學生大使
一於該日休息。
年「平時未必戈沒有可能有 港介紹給外地同學認識二辦理,
儒利等的講座;參觀旅 四 |地方,很多都是同學們,名若格。但 [正確及更具自信地把香 香港旅遊協會總辦事處 月,此機會,-
實有關香港|連同已與安的申請表格 的知識,以便能在日後,於辦公時間內親自到
機會可到訪的。:..名時,蒗类问海外學校 參加的同學將可藉「入學證件或1-20 表格,
|樂活動如營等。這些銀行教育輔導組索取報 一及製衣廠,以及參加康教育協台辦事處及恒生 「系統、電子廠、食品 學生質獎學金組 國際 ,貨櫃碼頭、公共交通 事處、教育司署海外留 :政府部門例如房屋署 五樓香港旅遊協會總辦 洋公園、宋、太空前一百前往中環康樂大廈州 公,遊機構如各大酒店,海,可於六月五日至二千 此外,申請者在報
,有興趣參加的同學
有關香港工商業及社會、澧。.
镪辦第十七間「學生】 一協會又即將於今年財務 ||| | 同學將被安排出席多個|四周活動者將獲發給經 | 外深造本港學生參加。三日舉行,費用全免, 使一活動,歡迎前赴洲,饒定核七月五日至八月 一如過花,參加的[惟名額限一名,完成
〔港訊〕香港旅遊」,負起「學生大使」任 ,今年的學生大使活
首日行主席博全(左二),接受捐款。
舞蹈節的演出! | 日於行之香港國際青年 七月十三 | 市政局之邀,行將來港
現代比色方法運用
REFEREECE ,該團月在英國費 【時等地说出,獲得好評
一年前]辦而成。兩足 跡遍及全球,僅前往怎
[總監安 賀嗯於大 現代舞選團,由該團的
KEEYE
12-
永愛風航空公司 「兩祟,是次來港演出,
灣大會堂演 | 日在上水北區大會堂及
一,又於七阿廿一放 【堂劇院演兩場,此外
| 丹十八几及甘且在大會
希律王之歌 |
傲欣舞蹈期將於七
「哈地取材自著名数
40332 gr
[來客的赅門、「路
「括「天外來客」
咸宜,今次表演川
安寧的社會正面臨大外
「鬆兼而有之,可說老幼
| 演出案材豐富,嚴肅性
AE
出
can be obtained
from air.
(iv) A: oxygen
B: hydrogen
C: nitrogen
2H2(g) +02( g ) ——H20(L)
201 1mol
2vol
1vol
100cm3 3
? em
vol of On reacted
vol of
x 100
50 cm3
reacted
vol of the remaining gas -vol of 0
1000
=0.005 x
23
0:217 mol da
Dilute sulphuric acid.
(11) The iodide ions were
oxidized to free iodine. Which imparts a brown colour to the solution.
It is because iodine is reduced by sulphur dioxide.
2-
in excess:
~(100–50)
-50 cm
(or, I,+S03
cm
21 +21 +80, ~~)
changes from +4 (in S02) to 46.
(in S
II: No(8)+302(g)→→2VH,(g) | (iv) 0,N. of sulphur
1mol: 3mo'l i.e.1 vol.
3vol
co
100cm3
2o1 2vol
?cm
vol of N,, reacted
x 100
2
(v) The set-up is shown
in the diagram below.
-333 cm
NH3 formed
100 cm
=66 cm3
dilute hydrochloric acid
the
vol of the remaining. gases
sodium sulphite
CH BY CHB
It is because gas collected in the first test-tube consists of mainly. air.
(iv) The porous pot acts
a catalyst.
(v) The thermal cracking
can be used in industry to break down large molecules into smaller ones.
(b.)
(1) This is to remove any
metal oxide on the metal surface.
(ii) is less reactive
than copper. It is because copper loses electrons more readily than“ X:
iii) The order of
decreasing reactivity is. Y>W>Z>X.
(iv) Y dissolves and
reddish-brown powder of copper is deposited. The solutions turns from blue to pale-blue.
2+ -Y(s)+Cu ́ ̄(aq)
2+
Y(aq) +Cu(s).
In this case, the voltmeter would not register any reading because methylenzene. is a no-conductor and there is no current flowing.
B is hydrogen gas.
It gives a "pop". sound on applying flame to it..
(ii) It might be water.
(iii)
It would turn anhydrous blue cobalt(II) chloride. paper pink or white anhydrous copper(II) sulphate blue.
Cis nitrogen which
-vol of Ng in excess-
vol of NH3 formed (100-33)+66
= 133 13 em
2
White precipitate o barium sulphate is
-seen.
(2) Both barium ions and
hydroxide ions
decrease in number.
This is because. Ba ions are precipitated as Ba§0, and OH ions are combined with Ho
ions to form
water.
(ii) Starting from B, there will be no more reaction and any further addition of acid will introduce more ion's into the solution, thus increasing the. electrical conductivity. (iii) Vol of 50
required=23.0cm3
(iv) n(Ba(OH)2)
50
1000
polfacted
*
=0,005 mol
According to the following equation F2SO+Ba(OH)2 →BaSO imol mol.
n(H2SO) reacted =A(Ba(OH)2) reacted =0.05 mol
concentration of
H2SO
· Pyrex test-tube.
-delivery.
tube
brown. Solution
The OH(aq) from sodium hydroxide solution reacts with ][ ̧0* to form water,
thus shifting the equilibrium to the right, so, more solid: acid (HA) dissolves. (ii) The addition of
hydrochloric acid increases the concentration of
HO
0 thus shifting
the equilibrium to the left, so, more solid acid (HA) appears.
Effervescence takes.
place as
H30
Co with sodium
carbonate to give CO. This will shift the equilibrium to the right and more solid acid (HA). will dissolve. (i) (1) The family is known
as the halogens. (2) p=2, q=8_and_r=7 (3) E; because it is the largest of the three elements in size and
mass,
thus having the largest inter- molecular forces,
(ii) The electronic
structure is:
A
D
B; because it is small in size and has a strong tendency to gain
to an electron attain an octet. (iv) C: magnesium
D: chlorine E: bromine (1) X is MgCl and
is
KOREKYZE
·港來月七團蹈舞欣歡英
場四演節蹈舞年靑際國 地哈路羅及客來外天括包自項
MgBr2*
Add silver nitrate. solution, acidified:
with dil UNO,, into the aqueous solutions of X and Y
separately: X would give a white precipitate of AgCl while. Y would give pale-yellow precipitate of AgBr. (2) Melt the compound X
and electrolyse the molten X. D would be deposited at the cathode.
Tube A acts as
cold finger and condenses any escaping
(ii) It is a solvent. (iii)
(1) The waxy solid is
polystyrene- (2) The equation is
C=C
-H
(iv) The kerosene vapour
might catch fire. This hazard could be: minimized by heating the test-tube.
containing styrene and kerosene in an oil-bath.
(v) The bottles are made by blow-moulding method.
i) Magnesium carbonate. solid dissolves and gas bubbles are
(ii) MgCl,(s)+2}!* (aq)—
seen.
Mg2 * (aq)+R20(L)
+CO2 (g)
Molar mass of MgCO=84 g
(MgCO),) added
=0,060 mol
(H,S0,) present
25 1000*2
=0.05 mol
1 mol of H2SO
reacts completely with 1 mol of MgCO3
n(Mg€0z) >n (1,504) MgCU, is in excess
iv) This is to
8
concentrate the solution by
evaporating off some water NOR slow cooling gives large crystals.
(2) Rapid cooling `give:
5.
(a)
small crystals.
(1) A: nitrogen(11) oxide
B: nitrogen(IV) oxide (11) (NO2)
(1) Platinum can be used as the catalyst. 4NH+50,→→4NO+6K2O
(2) Since the reaction is
exothermic, so, some of the catalyst may be vaporized and hence lost in the due
course
In stage II, 0, in
air combines with No to give NO. However, at high temperatures NO
A decomposed
to give
back NO and
02. Thus, cooling is necessary before the reaction takes place.
(iv) 4N02
(v)
(1) The yellow colour is
due to the presence of dissolved NO2 in the
nitric acid. (2) The yellow colour can be removed by blowing air through the acid, thus carrying away any dissolved NO gas.
(vi) Nitric acid could
be used f
(1) for making
fertilizers; and:
(2) for synthesizing.
organic nitro- compounds.
(vii) He should first
wash his affected hand with plenty of water.
(b)
(1) Two of the reasons
are:
(1). To allow the water
vapour to escape; (2) To prevent any loss
of the anhydrous solid.
(ii) Mess of water of
crystallization. the sample
(22.96-21.93
-1.05 g
and
(iii) Mass of anhydrous
cobalt(II) chloride =(21.93-20.63)
1.30 g
(c).
Molar mass of CoCly
-130 g
18x 1.03 130 1.30.
x=5.7
It is probably that the water of crystallization has not been completely driven out
(i) Detergent II is a
soapless detergent. (ii) Sodium hydroxide and
Fats/oils.
(iii
(1) White foam is formed
dirty white precipitate is obtained
(2)
Little foam is obtained No precipitates obtained'.
(iv) It is this par
(vi)
0
) Detergent []) is non- biodegradable, thus causing pollution problem.
(1) The detergent can the oil, it to be dispersed in water. |(2) Detergents may be
Loxic and hence kill the fishes.