1975-02-17 — Page 21

(b) Heat:o: neutralization. This' is the beat change when one gue equiulent of sold, is neutralized: by one gm. equivalent of a bas, the

ENCE LIBRARI

17 FEB 1975

#8 CITY HAM! 報日僑R

育教偡 頁一第張六第

日七初月正年卯乙巨变

WAH KIU YAT PO

育教僑

華

The mizzor has to be rotated through an angle, a, such that, the raya AD and A10 from window

are reflected into the eye

ein r

in 609.

1 = 359161

·AOBO

JA +

a cyolio quadrilatex

1800 #% = *83

1975

600

中學會考專欄

KIDEMIA

化學科(十四) 陳湛杰

CHEMISTRY (#14)

Solutions for Chemistry (#13) Nultiple Choice Questions

Conventional Questions

1. Le Chatelier's Principle states

when conditions under which that

a. aystem operating in equilibrium. and changed, the systen will shiri its equilibrium position in a way

will reduce the affect of the that change. In a chonice syetem, the variable conditions include. temperature, pressure and volume. (a) For the system FCP1+01 * In the vapour state, phospho- bus pentachloride diggociated to ar equilibrium mixture containing phosphorus trichloride and chlorine

he process la endothermic. The Coward

d-reaction (the reaction. towards the right side of the equation) ban the affect of loubling the volume without change

in masn. Under given experimental conditions all the three”

the three componente

behave no gxaea and conform to Avogadro's hypothesis. Applying Le onatelier's Principle would indicate that "a diminution-in- precaure must bring about a grate degree of dissociation.. Increasing the temperature of the system would

Increase, the dissociation of nhosphorin pentachloride since..thi io au endothermic process.

For

the

Oyatem

+ Hy

At experimental con

conditions, all the four components exist as gages. Since the total number of gaseous Iolecules on the left hand side equals to that on the right hard side there

zo change

is no

mylime the reactions eith

either way. in Pressure

dufore changes.

WALE

affect the equilibrium position

However, the forward reaction is ac

reaction sing carried out in very

digute aqueous solution. Thus for hydrochloric acid with sodium

liydroxia, the value is 1377Kon1

en gu aquilent.

na

HC1 (34) Nachfog)

•7001 (ay) - 10(1) + 13.7Koel.

It is found that for strong acidg

l stay bases, the values

obtained are very close to 13.7,

this is due to the fact that for

all muli neutralization reactions, basically is:

H* (áq) + OH (ay) —

H20(1).

(c) Heat of formation. This is the heat change when ous mole of a compout is formed from its element under given conditions. The formation of water from guaecuɛ hydrogen and oxygen is found to be 68.3 Konk per mole at 2500 and

atmosphere pressure.

H2 (B) + ± 02 (8) →

20(t) + 68.3 Koal

(1) Heat of atomization. This 13 the nest required to convert one ga molecule of an element from ita normal state at 25°C and 1 atmosphere pressure into free atoms (a) + 103.4Kcal = 2H

(6) deal of hydrogenation. an important information for

This is

It

astunted organic compounds, is the neat change when one mole of an unsaturated compound is cont pletely converted into the corner

ording saturated compound by reaction with gaseous hydrogen

(g) + H2(g) =

;

[[C2H2 (e) + 32.61a7

(r) Other specific hente of react- “ion include dissociation, crystal-

lization and ionization. Heat charges are 2160 usá002ated with changes that are not reptions, e.g. dilution, solution, sublimat- ion. Heat changes that involved only physical changes of state include atont heat, af. fusion and Tatent

heat of vaporization. Questions for Next Week"

The questions in this issue a re

bad to 5. Chemistry in Society; 5-1 sources of raw materials and energy 5.2.Synthetic polymers and naturally occurring macromoleculca; 5.3 Chemical" imustry.

What

at are the energy resources available to man? Indicate which. ones are most Convenient for use.

as fuels.

themic process, implying that a 2. Describe one method for the

higher temperature will favour a shift of equilibrium towards a greater concentration of carbon monoxide and water vapour. (c) For the synten Me 02210

The equation indicates that similar to (b) the number of molea of gases at the right and left-hand. veidā, rowning the same. Thus change

O pressure will have no effect

industrial preparation of chlorina What are the reactions of chlorine with

ith (a) potassium iodide solutior (b) ammonia (0) Istus solution

Water (c) hydrogen (e)sulphurt. 3. What do you wiErstand by

ollution? Indiente the chemical basis of air pollution with. referende to Hong Kong.

Klong the samo ray, OB, A

By geometry,

ZAON

= (complementary to GE) = [ION (Z1 = 20)

A ON FOR' (/1/1)

Zhou - /.OE - LAQA 2/BON! - 2/BON - LAJOR 2 (BON ·FOR) = LASDA

2/100 = 20

20420

tan. =210480

Mohayen maxímún field of view through window 2, the mirror ehould rotate 27648*: (11).

Focal length of lens, f. 20 om Object distance, u 10 am- Image distance v cm with Jens equation,

1

2010-20 cm:

A pacified, treat, sal virtual iunge in foxmish window 1, 20.oa on the left side of the leuc.. -(0)

behind

O is the image of 0.on, the

It is (15+15+10)am fro mirror.

the lens,

With D' as the object: focal length, f 20 cm object distance, u 20. Image distance v en

+

real,..

=

inverted, and diminished image is formed at a distance of 40 cm from the lens on the samĘK side as the observer.:

2(s) u: object distance

va image distance

.

u(om) 30 40 50 60 70 80 90 100 V(cm) 30 40 32 30.5 28 26.7 25 21F

upon the equilibrium.. Eowover, 25.

on

endo thermic process, the proportion

中學會考專

10

3.3 2.5 2.1.67.14 1.25 L1 1 167.25 29.3.3 36 3.7 3.8 4

the oxidation of nitrogen is, an

of nitric oxida et equilibriu

Loreases with a ride in temper- ture.

(a): For thu ayutem

- 2502 + 02

250

Here two molen of sulphur

dioxide gas mouli combing with one

volume of oxygen yielding two mo198

of sulphur trioxide gas. Therefore

there is a reduction in volume for

The

forward reaction. According to

Le Chatelier's. Principle, an ine

Crease, in pressure would

cause

shift in the equilibrium position

trioxide.

towards sulphus the process is

Tir the las T. RE

物理科(十四) 陳永熾

exothermle for the forwarû reactior 1(a)

the reveres change wou

would be

dother10.

Thus the decomposit-

ion of the sulphur trioxide would

become more and more significant Re

the temperature risés..

(e) For the system

Caco,

Ca + 002

This is an example or a haterogenous reaction involving two: solida and a gase In the case of a

closed system, ie. in the Line Foomponents are all kept in a closen

Can Brit Youls be

VeRsol, an

catablished.

solids occupy a much smaller, Volume (in relation to the mumber of molecules) when

in

with gases.

increase

fe would inhibit the forward reaction to a greatior The necomposition of arbonate. is an endothe mic

process, so that the formation or Galaium oxide and carbon dioxide would increase with increasing temperature.

Chemical processes invariably involve energy changes. The most common types of reactions that fooour included combustion, Bolution

dilution, neutralization, atumi- isstiva and hydrogenation. Any Chemical stuly of a chemical system shwuld not only include the trans- formation of reactante into pro- ducts, but should also involve a considemtion of the energy changae during the pruusss. A study of the kind

of energy ohanges involved

öflen gave some information as to the detail mechanian of the procese involved.

The simplest kind of study is concerned with the evolution cỡ

· absorption of heat and is known as thermochemistry.

However, 10

should be noted that in special:

other fome of energy changes may be important.

Thus in a battery, chemical reactions would release electrical energy; during. photosynthesis, light energy la absorbed and tinuaformed into chemical bargy; in reactions involving an increase in volunio (ong, gas evolution), mechanical work 18 done in expansion.

Reactions that give heat do the aurdunding are known se exothemic processes, those that absord heut from the Burivandings are known as tendothermic procasa. Heati

ohangoe arexpressed in teme of Foalories cr kilocalories, heat Folangas for a gwn renation fo constant under a fixed set of physical conditionst

crisphere are many types of haste of

action, the more important unene. tated below="

(s) Heat of combustion.

Thin 10 the heat changs when ore mole of a substance is completely burnt in OXYSAL. For the complete combust- lon of methane the value in 21320) per mold.

OH, (8) + 202 (x)= | 00,(6} + 210(1) + 13 Real

PHYSICS

(1) For mirror M-3

Limitation of raya re- flected into the eyes of ob perver la between C, and OA, They are the reflection of Xo, and YO, respectively.

For mirror Mat

Limitation de between OFA and "A. They are reflection of Wo* und 30" JA

Conclusion: The parson can't gon Aimselt from either of these mirrors at position A.)

(a)

Sitting at position B, observer

at position A can sec inages. from-

Mirzor Ma

1. Image position of 1:

I ie as far behind the clitor as the object is in frozE,

2. Image size:

3.

Images of plane miriors are of the same size as the object. Nuture of images, t

It is virtual, ereot, and lebelly inverted,

Mirror M

Image: I, direct reflection from

H:

1. Iie og far behi

object in in front

as the

2. same size as object is in front

3. virtual, erent, laterally

inverted,

100.69 12, Becond reflection:

Flot a graph with 1/u against 1,

and

A straight line graph is drawn. Produce the graph to cut x y-axis at A and B ruspectively. At A, == 0:

therefore

A roads 5 x

ལ

1

+

At R,

0; 100

20 am.

the fo cel Length of the cones mirror is 20 cm. 2(b)(1)

5: lateral dis

placement

20 om.

The incident rev A0 18 refracted towards the no mal DC. When it mes be the lower surface, it is again refracted. This time the emerged ray 0A is away from the

The lateral displacement is. measured by:-

Sd sin A

where X is 45° and

sin i = - oin 24°44a

380521 12

the deviation is measured =2x 0.4184 ·0,6276:

60° 12

38°521

(this problem can be solved foy. drawing in actual Boale and angle Die measured.):

(125)

A0 incidents at 90°, there is no refractionA It hits the other face.

which is

at 50

greater than the

critical ang18 D

(= sin

Total intemal reflection takes plane. The reflected may OB energ emorgaa normelly out of the prism.

(iv) as in (iii),

critical angle c

the c

(egin.

less than 45°

AO.

is totally internally. reflected twice, and emerges as 0*8 out of the Frdam.

Questions for this week

1. (a) Explain the meaning of

critical angle and total inter- bel reflections ja tahu

(b) You are provided with a cubical thin-walled, transpar ent tank; some liquid, opticai pins, and a short ruler. Describe a simple method of determining the critical angle of the liquid. Calculate

(c) How would youl

the refractive index from your meant?.

Source:

from a

(a) on the Lower face of a rectan- gular glass slab of 1.603 re- fractive index, and 2 cm thick, strikes the upper surface and the totally reflected rays out- line a circle on the lower face.. (i) What is the diameter of this.

circle? ·

(11)IF

slab of another glass refractive. Index 1.43 and 1 cm thick, is placed on the upper suface of it, what will happen?

2. (a) Make a table of three col- wans to compare the parts of a camera and an eye. In one col- umn list the various functiona to be ferformed, and in the other two identify the that perform each function

account of the com

and explain men eye defects how their effecta ted..

Give an

may be correc-

(c) An object. 4 cm high ie pla- ced 6 cm in front of a thin cor- vex fena which has a focal Leng th of 4 cm and produces a real

Find the height of the inage. image. Also find the distance the object must be moved along the axis, to give a virtual ima➡ ge of the game height.

(d) A painting consists of:-

elements

flower pot.

1daves

·colour

"yellow

flowers

green red

table cloth

peacock blue

background.

What will the painting appear if it da-illuminated by, first,

light, white

and then, by red light, and finally by green

116 what will it appear, if

observation is made under (i). a yellow filter, (ii) a blue filter, (111) a green filter.

新數學(十四)・國農

MODERN MATHEMATICS ($14)

Coordinate Geometry II.

The straight line

a. Elope-intercept forms y··¤x+b

b. Gneral form: Ax+By+ 0 0.

c. Paint-elope for: -y-

a. Two-point form: y-y1

e. Intercept form:

++

f. Nomal (polar) form:

K GOB, W:+y sin

Notice: when p=0,

the positive

direction on CN is the upward direction.

g. Normal form:

Ja Ax+ By + O

The mdioal sign is opp eita fo that of constant 0.

h. The perpendicular distance from

a line to a point..

Equation of line: Ax + By +00

or * 009 W + y sin w p≈ 0

paint: (1)

tB

real thickness -

apperent thickgra

th

Distance:

Ax¡ + By + 0

d.

EN AS

+ B

น

real thickness apparent thickness

1. is as far behind My an I iad t(1-2), ≈ 8(1 − 3) = 8 × ↓

iá front of it.:

2. same size au object

3. virtwil, erect, no later inversion with rospect to object.

(b)(1)

window !

20cm

Visw

in 450

(This problem can be solved by scale drawing and measurement.): (ii)

1.8

-Ray domes out from the prism after

being refracted twice,

Bin 1.

ain

=

009 Y, einw-p

When the given point ana the origi are on the same side, disabi Regative; when the given poirt and the origin are on the oppositive side,

dis positive..

When the given líne AB pas809 through the origin, the positive direction on the nomal ON le the upward direction.

i. System of straight lines.

System

of lines passing through the point of intersection of two given lines is given by Aqx+Bq3+0q+ K(Aq*+B¿y+Oq}

J. Condition that three linee

¡Conourrent.

If Ax+By+C, then A, B, C

A2x+B23+020

Ax+B37+0=0

= 0

日七十月二年五七九一层公年四十六国民兽中

1. Find the equation of the aira *through the print P, (-1, 3)

perpendicular to the line

5x - 2y+3)=0·

The alors of 1, is. Hence, the slope of the required line oqaule. By point-slope for.

-3x-(x +1)

or 2x + 5y -13 = 0 (Ane.) 2. Find the equations of the

bisectors of the angles formed by the lines 1 x + 376 0

L2 3x + y + 20

Let: P(xy) be any point on the bisector. Then, P is equally distant from the given lines. d distance from L to P, and d =distance from L to Pthen and are numerieally equal.. Since however, P is on the same pide of both sides as the origin,. dy and d are both negative. Hence

3+3+2

Aftar

d ruduging we got Xj+ (Ann) x + y = A For the external angle bisectorip djm

after reducing we gat

(Ans)'

0:00

of the line:

3. Find the bush P1(3.1) and the

30ing through P

Foint of intersect of L.': 31-5310 and 1x+y+1]

If

then

The system of lines is reprosented by 3x-2y-10+k(x+y+1) = 0 en

(2,1) lies on this line, X-23-1 must satisfy this equation. Hence 6-5-10+k(2+1+1)=0 whom k

Substituting this value of kaŻYT simplifying we have 21-11y4:310 Solution to exercina 13′′

1.

Ans,

ABC A(x,y; } B(xy »¥2) C& Die the mid-point of BC D= [* (= + xy ); ? (32+Y3 ·}} |

Let G be the centroid of AEC, then AG: GD = 2:1

{+2+Yzz j

2

+

2. The area of (2,3), (~3,-4)

(5.

(2,2) is

8+3+10+5

31 unit squares. Exercise 14

1. Find the equations of thờ ta

sent to the circle with the origin as centre and radius 4. which touch at the anda of the diame eter whose inclination is 150° 2. Find the gentre and the radius

of the circle inscribed in the triangle whose sides are 2x+ya12, 27-y=-4, X-23-4-0

3. Find the equation of the line

Laying through the point of

ersection of L: 2x+y+1 = 0

inte

and L1 x-2y+1 = and parallel' to

- 4x-3y-7 - 0

數學科(十四)

文長源

ADDITIONAL MATHEMATICS (#14) ·

Solution to exercise 13

1. The coefficient of x in the

expansion of (1+x)* ia

•·+(−1){} −2)••••(*_5+1)

[1(-1) (3) •*•*(-2x+3)

(2) 1

(((2) (4)16) ►*** (21)

• * • (1+x)==1+dx=jx2

Put x=0.02 then J.02

=1+0.01 (0.0004)+ + (0.000008)

1.01-0.00005 0.0000005 =1.00995 Since 225 = 152

√226 15(1 + 225)

15(1

+

-15 + 30.

450

8 (225)

8(15)(225)

-16 (225) -

15.03333 0.000037 + **

15.0333 (correct to six signifi cant figures)

2. The orthocentre i is the point

of intersection of the lines

through A,B,C perpendicular to CA AB, respectively.

Any

For

Any

given by

0.

given by

"4x+y=6+k" (11x+73+9)= 0. or (4+11kc2)x+(1+7k )y+9k!−6 = These lines are perpendicular to BC and CA respectively

= and

k- and k!= -1

The equation of AH and BH are therefore

x-4y+240 and 5x-3y-33

4y+240

Solve

1.5x-3y. 330.

x= 12 y = 9.

The co-ordi

dinates of

are (129)

orthocentre

3. tan 30 = tan 20 + tan D' tan 20 = tan 30 – tan @

gin3900se – sinecos30 tan 20 m

G083000 Be sin 20

or

sin 20 coe 29.

сов. 30 сове Hence ofther sin 29: when 20-n|

or coa 20 = COR 30 COB

a a (cos 40+ con 24)

COB 20 = 008 40

40 2n77. +

± 29

20 = 2017 or 60 = 2077 The general solution of e are.

ny,(The form

is included in the form and

x4

kx. + 1 le a factor of 22x+5x + 2

x4 - 22x2 + 5x + 2- (x2 + kx + 1)(x2 + k!x + 2)

The coefficient of x=10 ko-k*

The coefficient of x=5 2k+k 5 1.0. k5 Hence, x4

2. How many different numbers dI Ə digite may be formed with 01234567 How many of these will be event, 3. A cup is in the form of a hollow hemisphere of internal radius 400. with its top horizontal. Water le

into it at the rate of

poured

At what rate de the rising when the depth of in the cup ie Jom? :-

4. The inscribed circle of the triangle ABC touches 30,CA,AB at F,Q, respectively. Express the -RPQ in terms of the angles of the

Prove that, it denotes the area:

the area of the APQR 18

+

英文科(十四)·阮士仲

ENGLISH (#14) -

2. Composition How to tell a

By and large, # short story bas to be short (Suppose that we agree ho short da shart) and is normally written in the past- tenge. It may be written in the first person narrator or in the

third paraón Tarrator or in both.. And it contains. Zour essential Farba:

(a) Beginning (a) Climax

Developmont Ending

To begin a short story, we must introduce our characters and explain what has happened, when it has happened, and where the event has taken place. These are to be done in the first or the first two But each of the above. paragraphs. has to be developed to certain extent, paving the way for a climax, the highest point of the

the story. After the climax, atory should be finished as quick- ly as possible.

As an illustration, let us con- sider the Samson's Riddle story from the Bible:RMA

Samson, son of Hanosh, went down. to Timnath and encountered a young lion growling in the vineyardo. He fought bare handedly and tore the

Ha than went down lion in pieces. to see the Philistine woman ha

When loved and proposed to her. Samson turned aside to look at the caroase of the lion, he saw a

hones swarm of beeg in it and some hou He scraped the honey into his hands and went on, eating as he went.

When he came to his parenta

he gave them some honey and they ate it. He did not tell them from where he had

Samson obtained it. gave a wedding feast and had thirty young men as his beetmen, He asked them a riddle and if they could answer it during ·

the seven days of the feast, promised th them thirty lengths of liner and thirty ohanges of clothing.

middle went as follows;

At

The

ething

Cut of the eater came some

to eat;

Out of the strong came something

aveet.

the end of the third day they

failed to get an answer. Then they, threatened Samson's wife to get the answer for them. She was forced to

coax her husband with tears and

tander words. S seventh

day

She succeeded on the Before Samson entered the bridal chamber, the men said to him:

What is sweeter than honey?

What is stronger than a lion? To which Samson replied, "If you had not ploughed with my heifar, you would not have found out my The story above 20

dly above le analysed as

riddle,

follows:

rom. Samson, son of

(a) Beginning: From

(b)

Manoah to and proposed to her!

Development From When Sanson tumed aside to 'Out of the strong came something sweet. (c) Climax: From 'At the end of the

third day to What is stronger than a lion? 1

a) Ending! From To which Samson

replied to found out my tziddle*.

英文科 (十四)

ENGLISH (14)

Choose the baut wer

in the brackets.

Exempler 111e bread.

·Breakfast,

Write the LETTER

then rice for

(c)

the better ·B1012 C. better D. best E. the bout)

to lock after

1. Foutu brother do

hindelt.

(á old B, se old

C. mough old

3. old andìgh': 'F. `oldent)

4. He in hospital for the past two

will be B. in 0% xên. D. is being

3. The man said he was not a thief,

<A», wasn't he "B.didn't he 0. van he

D. did he B. wouldn't he)

4. One of the teachers in our

false teeth.

hool

(4. have 3. having C. 10 having

1. will be having B. has):

when the lesson wan

5. The girl fell

on.

(&. asleep 3. sleeply 0. slept.

D. sleeping E to sleeping)

Choose the answers which best completa

the following pasange.

Tony Chan likes fishing. Testerday afternoon he 5, (F. decide C. decides R. decided 3. deciding to decide) to" (try his luck at the seaside, near

his house, His brother, Sex A. wanted 7.(F. go Q to go going Sent F. gone) with, him. "8. (Would Q. Will R Rave 5 Mar T. an] I go?" he B.[ naked. "I can carry the 9.[P.

ball Q. pen R. cege S. fishing rod T. medicine) for you," Tony agreed. Soon they 'wore at the seaside. Although the fish 10. (P. that Q. whom R. what 5. who. T. where) they 10.(. caught were small they went base bappily.

42 32 2 =0 | A3 B3 03

Xo

22x2 or (x2 + 5x + 1}{x2

--5 +

→

5x

} = 0

5 ±

or

Exercise 14

AMATERA

1. Fim the equation of cirole which touches x2+у2-15x+5y=0 at (1.2) and passes through (0,2)

1. D

2.

3. B

6. R

7. Q

8. 3.

9.5

is the condition that three linės concurrent.

Examples:

5.

10. P