三期星日九月四年九六九一公年八十五國民華中育教僑華
真二第張六第日三廿月二年酉己曆夏 WAH KIU YAT PO.
郭日僑
1969TFUL?
化學科
廿三
三九六九市中文栄会考試題預コ
英文科
王淑方
(#)
王錦釗
CHEMISTRY (22)
LESSON TWENTY-THREE
Although chalk is insoluble in distilled water, but it is soluble in rainwater, This is because.
A
rainwater contains dissolved carbon dioxide.
B rainwater contains dissolved hydrogen sulphide. Crainwater contains dissolved sulphur dioxide
D distilled water is not a good solvent
E rainwater is purer than distilled water
In the reaction 2KC103 ZKG1
302
the addition of manganese dioxide will
A have no effect
B cause less oxygen to be produced
cause more oxygen to be given off at the same temperature.
produce more
is raised oxygen, provided that the temperaturi
produce the same amount of oxygen at a lower temperature
Copper may be obtained from brass by
removing the other metal by dissolving it in hydrochloric acid
B removing the other metal by dissolving it
nitric acid
fractional distillati on
D melting the brass and separating the copper from the other metal by fractional crystallisation
E heating the brass in a current of chlorine to
remove the other metal
Sodium hydroxide solution is added to ferrous sulphate solution and the product is heated in contact with air. This results in
A a brown precipitate which undergoes no change
B a brown precipitate which turns green on contact
- with air.
a green precipitate which turns brown on contact with air E
a green precipitate which turns brown throughout a green precipitate soluble in excess sodium nydroxide solution
Copper sulphate solution is electrolysed between platinum electrodes for a long time, until there no copper left in solution. If the charged electrodes are allowed to remain in the solution, what will occur at the cathode?
A Copper is deposited
Hydrogen is liberated
Oxygen is liberated
Copper is first deposited; finally hydrogen liberated
Copper 18 first deposited; finally oxygen is liberated
5. When sulphur dioxide is bubbled into a solution of
potassium dichromate, the solution turns
colourless
green, with the formation of a yellow precipitate green, but with no precipitate yellow, with the formation
E yellow, but with no preci
yellow precipitate
When a white crystalline golid, I is heated in a test tube, it first gives a crackling noise, then it decomposes with the evolution of dense brown fumes. When a glowing splint is put at the mouth of the tube, it is re-ignited. When no further action occurs, a yellow residue remains in the test-tube. When I is dissolved in water and ammonium hydroxide is added, a white precipitate is formed which is insoluble in excess ammonium hydroxide,
X is probably
lead nitrate
lead oxide
C sodium nitrite
zine nitrate
zinc oxide
The same electric current is passed for 1 hour through solutions of copper sulphate and sodium sulphate in separate voltameters connected in series The electrodes in both voltameters are made of platinum. If 0.635 gm. of copper is deposited in the first voltameter, what volume of hydrogen (measured at N.T.P.) is liberated in the second? (Cu 63.5)
0.224 litre.
8 1.120 litres
102,240 1itres
4.480 litres
B The volume cannot be calculated, as it depends
on the concentration of the solution.
When a drop of concentrated nitric acid is added to
a concentrated solution of ferrous sulphate contained in a test-tube
a brown precipitate is obtained
E the solution turns brown, and a brown precipitate.
is also produced
the solution turns brown, without any precipitate the solution turns deep blue
a green precipitate is formed
10. A solution containing 10 gm. of lead nitrate is
mixed with a solution containing 10 gm. of sodium chloride. What is the weight of lead chloride formed?
A10 gm.
B B.4 8.
16.8 8
D 23.8 g. E 47.6 gm.
LUTIONS
SECTION FIVE
TEST PAPERS
Answers to Exercise 33
(A)
(B)
Once there was a man who sold shields and spears in the State of Ch'u. He usually praised his shields and said, "My shields are so strong that nothing can pierce through them." After while, he praised the spears and said, "My spears are so sharp that they can piece through all vi kinds of things in the world." Then someone aske ed him, "What would happen by using your spears to pierce through your shields?" He had nothing to say. In fact, a shield which cannot be pierced and a spear which can pierce through anything, cannot exist simultaneously.
Once upon a time, a tiger was searching for his prey and eventually he caught a fox. The fox said to the tiger, "You dare not devour me, for I am authorized by God to rule all beasts in this world. Now if you devour me, you are doing it against His will. If you do not believe, please follow me and you will observe that all the beasts will scatter immediately." The tiger consented and thought that it was quite reasonable so he followed the fox. When all the beasts saw them coming, they ran away. The tiger did not realize that they were really afraid of him and
In fact, he thought that they were ran away. { afraid of the
Answers to Test One
(I) (1) (A (6). (S
(II) (1) E (6) $
(III). (a) (1)
E
(5) C
(10)
\(5)
(8)
(9) S
(10)
My mother asked me if I would go to the library at about the same time the next morning.
(ii) She told him not to bother to type the letter
and she would type it herself when she got: back.
(b) (1) John asked his brother, "Is it true that Jane
is leaving Hong Kong for Canada?" (11) My mother asked me, "Have you fed the cat
before you go to bed?".
(111) The boy said, "I must have made a mistake
my composition."
[IV) {a}) He was so badly hurt by fire that they decided
to rush him to hospital
(b)
She went home as soon as she heard that her aunt had come.
As the thief was afraid of being caught, he ran away quickly,
She kept on working as though she was very tired.
It is quite natural that little boys are. usually naughty.
Rainwater contains dissolved carbon dioxide, Chalk will dissolve in this very dilute solution
*carbonic acid' to form calciim bicarbonate.
CaCO2+ 140 • CO2 -Ca (HCO3)2
2. E A fixed weight of potassium chlorate can only
produce a fixed weight of oxygen. The addition of manganese dioxide will only cause the potassium chlorate to decompose more rapidly at
Lower temperature.
Brass is an alloy, consisting of 30% sine and 70% copper. The zinc may be removed by dissolving it in hydrochloric acid.
2HC1 ZnCl
Zn
Cooper will not react with hydro
ic acid)
When sodium hydroxide solution is added to ferrous sulphate solution, a green precipitate of ferrous hydroxide is formed,
Na So
Fe(OH),↓·
50% 2NaOH = Heating the mixture causes convection currents to be set up, thereby bringing all the ferrous hydroxide into contact with the air. Finally the precipitate turns brown throughout.
Fe(OH)2
[f] Jack was such a good
medals.
(g). He is one vi
that he won five
Enjoy work
(h) we like oranges because they are good for
health.
I have not seen him for three weeks The sum was too difficult for her to do it.
TEST ONE:
ส
TEST PAPER II (Continued)
For each of the following sentences, choose the best of the alternatives given.
The manager raised his salary and made him an assistant.
(A)
accounting. (C) accountant
(E)
accounts
(B) account
accountancy
Blind people use their hands to read
they also use them to make baskets.
(A)
brail
(C) brain
(E)
bray
(B)
(D)
braille braise
(}} The troops were ordered to try to destroy the
and heavy guns were brought up.
(A)
investigate.
(B)
(C) invalid
inversion investment.
(E) invaders
(4)
Does she know this
if she refuses?
(A) consequences
(B)
sequences
(C) frequency
(D) frequent
(E) frequentation
(5)
The master gave rewards to auch men as
them.
(A)
preserved
(C)
reservėd
(E) conserved
served (B) (D) deserved
(6) The passage 19 so difficult that I cannot
(P)
express (R) Compress
comprehend
no
expect
(7) Though life has few enjoyments, we still
to it.
(P) clink
(R) clip
(T) cloak
00
00
[
cling climb
:(8)
Be careful in your healthy.
and you will keen
(P) die
(R)
Q) dietetics (5) dielectric.
(1)
adored her -proud husband, but she was
fear of his fierce temper.
in
~{P) mortal
(R) immortal
(T) mortality
moral immoral
[10) The soldiers were poorly armed, our
offered a stubborn
2140 -
brown ppt.
When there is no copper left in solution, the remaining solution is simply a dilute solution or sulphuric acid. When the electrolysis is continued, therefore, hydrogen will be liberated. at the cathode.
10.
Sulphur dioxide reduces potassium dichromate to potassium sulphate and chromium sulphate. It is the chromium sulphate which gives the resulting solution its green colour.
3302 = 8230 + 6721004/2
• 4H2O
▲ is lead nitrate. When lead nitrate is heated, decrepitation takes place, brown fumes of nitrogen peroxide are given off together with oxygen and a yellow residue, litharge, remains.
(P)
assistance
(B) instance
(T)
insolence.
2Pb(NO3)2 -2P60
ANO
resistance insistence
山
With ammonia solution lead nitrate will give & white precipitate of lead hydroxide, which la insoluble in excess ammonia solution.
Po(NO3)2
2NH CH - 2NH NO, • Fo(OH)2V
According to Faraday's 2nd Law of Electrolysis, the weights of the different elements liberated or deposited are proportional to their chemisal equivalent s
C.E. of Hydrogen C.E. of copper
1.e. when 63.5 gm of copper are deposited in the first 2 voltamter, 1 grm of hydrogen will be Liberated in the second.
or when 63.5 gm. of copper are deposited, 2 gram of hydrogen will be liberated
1.6. vol. of hydrogen liberated at N.T.P.
22.4 litres
Hence whan 0.635 gm. of copper 13 nepošilea Tolume of hydrogen liberated at N.T.P.
0.224 litre
Nitric acid will oxidise ferrous sulphate to ferric sulphate. At the same time, nitric oxide is evolved which reacts in turn with more ferrous sulphate to form a brown compound with the formula Fe30 NO
6FOSOL
2HNO3 + 3H2SO,
Feu NO
NO
3F02(SO4)2 + 2NQ • 4820
(brown compound)
PD(NO3)2 2N9C1
207+2(14+46):
331
PBCL, • 2NaNO
2(23+35.5) 207+71
117
278
When 10 grams or NU1⁄2 are allowed reacu with 10 grams of NaCl, the NaCl will be in
exces9.
kt. of Fool from 331 gm. of 101N0312 - 210 8.
. of PbCl2 from 10 gm. of May 2
278 I
8.4 809.
gms.