頁四第張六第 日七十月三年辰丙夏
WAH KIU YAT PO
郭日僑
五期星
7.& 8. Both of them applying
'Fleming's right hand ru
新數科 (廿二)
女長波
Since P(of
(11)/
日六十月四年六七九一圈公年五十六國民载中 青教備藐
=
The en-ordinates of 0 are ( !!
is the point on ellipse
(i) Assume the main current
x2=25(1
flowing through the circui be. I.
-MODERN MATHEMATICS
(22)
OQ⚫OR=
From the voltameter
Solution to exercise 6 Section A
9x25(1
1976中學會考試題預習專欄
化科(廿二)
李國榮
1V 10 Ω
0.1A
(current) x (Total R) 0.1 x (10 + 3 + 2) 1.5V.
(ii) (Potential) - (current)
Intemal resistance
2cos e + 3sin ə =
- Zain 0 + 38in 0 0
(Pain + 1)(sin 0 - 2) 0.
sin -- or 2 (impossible) 200 or 3300
210g x =
10g
log
.16.
31og 210g. 1000 x-2
生物科(廿三) 卓唐慕
#23
BIOLOGY
CHEMISTRY (22)
14. Explain, the following observations
with appropriate equations.
(1) When hydrogen sulfide gas is
bubbled into concentrated nítric acid, a yellow precipitate, is ob- served, while a brown
ved..
(ii) When a piece of
is evol
re platinum
wire is put over a concentrated solution of ammonia, brown fumes are observed near the platinum. wire,
(ïïï) When a piece of zinc metal is
put into silver nitrate solution white crystalline solid is slowly formed on its surface:
B. When 7.95gm of a compound X were heated, the residue weighed 6.15gm. At the game time 0.49dm2 of a gas were obtained. If the gas volume was mea¬ sured at S.I.P. find the relative mo- lecular mass of the gas.
24. A current of > amperes was passed.
through a solution of copper sulfate. using copper electrodes. The time
used was 2hr.30min. Find the mass. change in the cathode.
#
B. Acetic acid is mixed with ethanol
and warmed in the presence of sulfuric acid. An oily substance is slowly formed and the reaction seems to be slowering down. Finally it reaches a point where no further reaction is ob- served,
(1) Has the reaction stopped at this
point?
(ii) If the oily substance is removed from the reacting mixture, what effect would this have upon the reacting mixture?
A mixture of sodium carbonate and sodium chloride weighs 4.00gm. The mixture requires 4c.c. of 0.1 Molar. hydrochloric acid for neutralization (i,s, no more carbon dioxide is evoly- ed). When excess silver nitrate is adred to the resulting solution, 8.61. gm of precipitate are obtained. Find the percentage by mass of the two com-
8 in the mixture. pounds
B. Explain the following by giving app:
ropriate equations:-<
(1) A stream of ethene gas ouickly
decolorizes a tert-tube of bromine water
(ii) When a piece of phosphories pen- tachloride is added to a little glacial acetic acid, misty fume gas formed.
When hat ethanol vapor is passed over heated copper oxide, the re-. aulting vapor turns a piece of damp litmus paper red.
(i) A compound is either sodium sul-
fite or sodium sulfate, how would you ascertain which it is? (ii) A solution contains either pota-
ssium chloride or potassium bromi de, how would you ascertain which it is?
B. Describe, with the help of aporoori- ate equations, how the following pre- parations are achieved.
(i) Sodium metal from sodium chlori
de.
(11) Iron from iron oxide. (iii) Sulfur trioxide from iron disul-
fide.
(iv). Oxygen from water.
0.1 x 2 =0.2V
(e.m.f.)-(V
drop (1.5 0.2) V 1.3V
Ans.
or terminal)
voltage
(current)
External
resistances
0.1 x (10 + 1.3V
(iii) Power = I. V = I2. R
(v)
Ans.
(Power dissipated) - 12.R2
the wire R
(0.1)2 x 3
= 0.03 W→
Energy
work done
Ans.
(power) (time)
(0.03) (1000 x 60)
1800 J ------- Ans.
0.199
0.1 x (60 x 1000)
0.000033. g/c
Since Area of nuad. ABCD 2-AC-BD-sin @
350-x70x20sine
sine
0 = 300
In AAPD
tan APD
6000
APD In APBC
tan KA
CPB
6602*
LDPC
=180
I suhere
of cylinder r2(25)
Suggested answers contd.
4A.
(1) To ensure successful cross
pollination flowers have:
a. colourful and conspicuous
petals to attract insects, scent which draws insects to it,
nectary glands producing nectar, which are the food of insects; and,
d. stamens and pistil enclosed
within corolla so that the insects would sure to brush past when trying to reach the nectar.
(ii) a. Dichogany: maturing of
anther and stigma occurring at different times in the same flower...
4B.
6. Since PQ//BC and PR/
AR
·RA
3 x (6x10
Question for next week
Ly and L are two similar
electric bulbs.
AQ
RC
Ans
AR
RC
(a) Explain if they would give
the same brightness when they are connected
(1) in parallel as shown in
fig. 3;
(ii) in series as shown in
Fig. 2.
φ
· Fig. 2
(b) Compare the brightness of
the bulbs in the circuit of fig. 1 and that of fig. 2. (1) if the voltage sources
V1 and V2 give the same terminal voltage;
(ii) if the voltage source V
gives a terminal voltage which is 2 times of that given by V
(c) The terminal voltage of V1
is 6V and that of V is 12V. The current through the electric bulb L, in the circuit of fig. 1 i 15 an (3) Calculate the resistance,
of each electric bulb.. (ii) Determine the current
through L în fig. 1 and that in fig. 2 respectively.
(d) A resistor is installed to
the circuit in fig. 1 to reduce the brightness of Show in the diagram how resistor is installed."
Since f(x)
T(2)
SINGING
1 is not the number in the domain.
Since p and a are the roots of
"-6x+k = 0.
=2, p
pa = 8
p+n=6 and posk a+2+h = 6
The payment in the fifth year
$10000 x (1+7%)
10. Since y tan A
sin A
800
n(n-
(r+1) 1
P(O)
P(1)
the
P(2)
10: P(3)
(v) Ethane from ethene
2. A galvanometer. having an internal.
resistance of 1002 gives a
4. B
2. 83. B 4B 9.1
full-scale deflection for a
X
10 3
O
5. D 10. C
current of 0.1 mA. Explain with
P(x).
14. D 15. E
the aid of diagrams how it may
·P(X)
Answers to last week's huestions
6. D 7. ARE
11. E 12. D
物理科(廿三) 何耀明
FHYSICS (23)
Solution for last week
·(1) 1. D 2. A. 3. B.
56. E
Explanation
4. (internal
It
::음
oven
closed
current 12.4 12 10:
0.04 ohm
x: (4 x 3600)
4800 coulombs.
Ans.
be converted into
(a) an ammeter having a range
0-20 amperesi
(b) a voltmeter having a range
0-100 volts.
(c) If the modified galvanometer
in (a) is used to measure the current through a certain branch in a circuit, the pointer is stopped at the 0.06 mA-mark.
12. Since the enuation of ellipse ABCD
What is
18 25+
the current flowing through the galvanometer? (a) The modified galvanometer in (b) is used to measure the potential difference between two points in a circuit. The pointer is ~ deflected to the 0.08 mA- mark..
Calculate the potential difference between these two points.
The co-ordinates of B and D are (0,3) and (0,-3) respectively
Equation of DP is
+3
1. dy+3d
Bx+3x
The co-ordinates of Rare.
Enuation of DP 183
ie. Protendrous: stamens mature before stigma Protogynous: pistil:: matures before stamens. b. Self sterility: ie, pollens
cannot germinate on stigma of the flowers of the same plant.
(3)
(1) A fruit may be defined as a
structure which encloses and protects the developing seeds. and sometimes aid its dispersal. It is formed by a ripened ova- ry or group of ripened ovaries. (ii) A true fruit includes only the
gynaecium. eg. cherry
A false fruit includes one or more additional structures of the flower, such as the receptacle. c. apple.
(4)
(iii) Some of the advantages of the
seed habits' cret
a. embryo is protected within
the seed,
b. can remain dorment during
adverse conditions;
stored food in seed enable embryo to pass through the early stages of its deve- lopment; and,
d. adapted for dispersal.
(2)
5A. Enzymes are soluble organic
compounds, protein in nature, made in small quantities by living protoplasm, but they are very powerful.
58.
They are biological catalysta. Their action is specific, pro- ducing specific by-products. Their effectiveness is affect- ed by temperature, pH and often the presence of an inhibiting agent and the concentration. of the reacting substances, Extracellular enzymes, eg. digestive enzymes are dischar-(2) ged from cells.
In the mouth, salivary amylase
changes starch to maltose, but has no effect on fat or protein, and needs a neutral or slightly acidic medium, In the stomach, proteases. convert proteins into pep- tones and need the acidic medium lipase digests some fat, while rennin coagulates caseinogen into casein, "Pancreatic juices is alkaline
and the proenzyme, trypsinogen is converted to the enzyme trypsin when it meets with enterokinase from the intes- tinal juice and continue further protein digestion. Erepsin converts peptones to amino acids, maltase converts maltose to glucose. (N.B. Many other examples
of enzymes may also be used, provided the substance on which they work upon and the products are clearly listed.)
(9).
(1) The porous nature of the egg
shell serves for exchange of the necessary, gases be- tween the developing embryo and the surrounding air. (2) (ii) 'a' is the albumen, its
functions are to protect the ovum from mechanical injury and serve as source of water during development of the embryo.
of (L)
·(4)
(iii) Yolk consists of fat and
protein, which provide food for making tissues.