1976-04-12 — Page 22

一期星 日二十月四年六七九一曆公年五十六國民牶中有教備

water reacts with sulfuric acid to precipitate sulfur.

真二第張六第日三十月三年辰丙歷

WAH KIU YAT PO

報日僑華

夏僑

C. III D. IV

E. none of the

above

Ind. I

B. there is difficulty in measuring

water accurately.

C. the reaction is andothermic.

D. two layers can be formed which are

completely immiscible.

water is less dense than sulfuric acid..

12. Magnesium can be burned in carbon

dioxide, because

there is carbon in the pas.

B. magnesium is very electropositive C. the process is very rapid.

D. the amount of energy evolved is very

great.

1976中學會考試題預習專欄

A.

II. As the

shown below:

物理科 (廿二)

何輝明

PHYSICS (22)

Solution for laat week

(c)

Cap at zero:

potential insulator

Both leaf and cap are in the same potential.

Conclusion: The leaf-divergence of a

gold-leaf electroscope indicates that there is a potential diff- erence between the leaf and the

care.

A is correct.

Dis

correct.

Question for next week

T. Multiple Choice Question

1. Local action in a simple cell is due

*toś n

A the sulphuric acid is too dilute

B. the sulphuric acid is too concentra-

.ted

C. the formation of a gas layer on the

olate

the presence of impurities in the plates

E. the presence

acid

impurities in the

2. Depolarisation in a simple cell can

be effected by

A. the addition of a dichromate

8. using a mixture of acids

C. the addition of chalk

D. the a addition of sodium hydroxide

6. the addition of sand

polarization in, the Daniell cell is eved, by

oxidizing the gas evolved: replacing the hydrogen gas metal

C. allowing the gas to escape.

D. stirring the solution

E. storing the hydrogen

A storage battery exhibits an noen- circuit terminal voltare of "^2.4 volts. 'hen loaded as th ́t 10 ammeren of cuITF- ent flows, the terminal voltage dropa: to 12 volts. Find the internal resist- ance of the battery. 4.1.2 ohm

D. 0.4 him.

5. Find the

A. 0.02 ohm C. 0.04 ohm To-0.24 ohm.

uantity of electricity which passed through a lamp taking a current of ampere when it is used for.

4 hours

A coulomb

B. 200 coulombs

C.: 4800 coulomba. E."none of the above:

2400. coulombe

6. A spark is produced by an induction

coil although the input e.mf. is low. Which of the following is responsible

for this high voltage in the secondary coil?

I. the secondary coil, has a large

number of turns.

II. the primary and secondary coila

are wound round, a core of soft iron. wires.

III, the 'make-and-break' device creat- es a very rapid change in the flux at the break.

AI only B. II only C. III only D. I and II only E. all of the above

7. Metal bar BA is aliding along two

steel bars with velocity V as shown in figure, the

if any, induced current through R,

A. alternating

B. produced by backe.m.

D. Iz

E. cannot be determined

Direction of magnetic flux, into paper

In

9. A brass rod XY is suspended horizon-

tally between the pales of a horse-shot magnet by two thin copper wires which are. connected to a galvanometer. order to produce an induced current flowing in the rod from X to Y, the roc should be moved in the direction

A. I

*B. II

R

100

Ri 312.6

men-inductive. winding cast

battery of e.m.f. E and internal resistance ? £is connected in series with a voltameter R1 of internal resis- tance 10 ohms and a piece of wire R2 of resistance 3 ohms,

The potential difference across the voltameter is measured to he volt.

(1) Calculate the e,m,f," of the

battery E.

(ii) Calculate the terminal voltage of

the battery: E.

(iii) Find the power dissipated in the

wire R2.

(iv) What would be the amount of ener

gy used up in the R2 when the circuit is connected for 1000 minutes.

If 0.193g of cooner is deposited

on the cathode of the voltameter

in 1000 minutes, what would be

the value of the electrochemical equivalent of commer? .

(vi) If the resistivity of the wire is

1100-m and its crOSS-

ction area is 6 * 107

calculate the length of this wire

化學

科(廿一) 李國榮

CHEMISTRY

How many grams of sulfur are present in the makeup of mole of sulfuric ad2;

Afgm2 B. 32gm

. What is the oxidation number of nit rogen nitric acid? 4.43

B. +5

3. What is the

bon monoxide

D.

at S..P. of car- can be produced from

12.5gm of a crystals

(020, H2 *2K20) by the addition of an ex- cers of concentrated súlfuric acid? A.2000e.c.. B. 22476.0, MC, WA80c.c. D. 20 liters E. 2 liters

4.1 black novder is either conner (LI) oxide or iron (TI) sulfide. This can be found out by the addition of:

A. dilute sodium hydroxide solution..

B. dilute hydrochloric acid.

C. dilute sodium carbonate solution.

.D. dilute amonium hydroxide.

oxygen gas.

·E

5. Tn the brown ring test, the brawn sub

stance formed is..

'A

a complex of coprer nitrate and ammonia.

B. a complex ion of metal ion and hydro

xide ion from water.

с

D

a complex from iron(III) sulfatė

and nitrogen dioxide.

a complex from iron (II) sulfate and. nitric oxide.

E. partially dissolved nitrogen dioxide.

6. When 4 Faradays of electricity are:

passed through a couper sulfate solut- ion using: copper electrodes, the mass.. of couper metal deposited on the catho-

de is approximately A. 64gm. A, 22gm.

D. "PERm. B. 47gm.

7. If one mole of sulfur (Sq) contains v atoms, then the number of stoms in one mole of nitrogen was (N) is

A. I B. ZO.

D.

E. Y

A. Which of the following compounds can be produced by the addition of bromine to ethener

A. CH CH Br

D.

CHBr CHBr

B. CBr Br

E. CH BYCH, Br

G..

CH_CHBг,

9. Which of the following compounds is most likely to förm aniónìc solution when dissolved in water?

A

hydrogen chloride

C. nitrogen, sanoids

5. iodine vapor.

710

B. carbon' mqxide. D. xvgen

47. Alenhols are me thers of a homologous

family because

A. they all give hydrogen chloride

-vanor when a piece of phosanhorus

pentachloride is added.

B. they are all soluble in water. C. they can be represented by the same

general structural formula.

7. they are all covalent compounds.

E. they are compsed of only carbon,

hydrogen, and oxygen.

Water is not added to sulfuric acid

in diluting the acid because

E, carbon dioxide forma a covalent com-.

pound with magnesium.

13. The electron arrangement of a sodium

ion is similar to that of a (an) neon atom B. argon atom

C. argon fon - D. helium-atom-

neon ion

Ak. Which of the fillowing is a mixed

acid anhydride?.

A sulfur dioxide C. zinc oxide

E. carbon dioxide.

3. sulfur trioxide nitrogen dioxide

15. In order to dissolve

ium, the amount of m ric acid needed is VAL: 250c.es B. 300c.C.

E. 1 liter D. Boncic.

gm of magnes- olar hydrochl

Answers to last week's nuestions:

2 E

數學科

(#

葉柏芳

(21)

TRADITIONAL MATHEMATICS.

Exercise 6

Attempt ALL nuestions in Section A and any SIX Questions in Section B.

Section A (Answer ALL questions in this section. Each question carries 5 marks. Show your working briefly; geometry the- orema need not be nuoted when used).

1. In the figure, AB is

a diameter of the circle

and CB is tangent to the

circle. IT AD=13,

DC

1

Find AB.

2. A tradesman fixes the selling price of goods at 30% above cost. He sells half his stock at this price, one-. quarter of his stock at a discount of 15% on this price, and the rest at a discount of 30% on it. What is his gain percent on the whole transaction? 3. Simplify:

COS(45

- cos(45+x) sin(450+x) – sin(45°-x

2 4. If 3x2+ax-3x-1

find the values

a. and

5. ABCDEFGH is a rect-

angular block with sides 3x5x2. Find cos e í.e. cosine of

FAG

6. Simplify: | 28+2 (27 −13- £48.

7. A's income is 50% of 8's income, and AE exvenditure is 70% of B's expendit- ure. If As income is 75% of. B's ex- penditure, find the ratio of A's saving to B's saving.

8. Let . 8 be the

Show that

of

Section B (Attempt any SIX suestions. Each cuestion carries 10 marks),

9. Find in terms of n the values of and b which satisfy the identity. (x-n+1)-(x-a)2 = 3x +ax+b.

By adding enuations of this form for x=0 and n=",2,3,.............k, find an expre- asion for

10. PABC is a tetrahedron with ABC an equilateral triangle of aïde a. \"If PA-PB-PC=2a, find the angle between planes PAB, PAC.

11. AB is a diameter of a circle, and CD

is any chord parallel to AB If Pis any point on AB, oro ve CF2+DP2

=

that

12. The normal work in an office was

done by A,B,C, each working 6 days a week. A did 42% of the work and B did 40% of its In a certain week, the work was suddenly doubled; C did no more than usual, A increased his daily amount of work by 150% for 4 days and then fell ill and could do no more. By how much percent did B have to increase his week's work to get everything done?"" 13. (1) If x=p2+2po-q2, y=q2+2pq-p2.

2 2

find the value of

(ii) Simplify

2b

E is

AC

14. ABCD ia a sduare. the mid point of AD. cuts BE at. F. Prove that

AEFEFCBCF=1:2:4.

15. (1). Prove the identity

(sech BeeB+tand tang) (secA tanB+tant secB)2

..

(ii) Solve the enuation

ܚ sinoܢܐ

7sin@coa☺. + 30

for 0.0360°

(1) Show that for real x,

always positive.

(11) Hence, or otherwise, solve the

inequality:

2

7x+12

C=3x+2.

新數科 (廿一)

MODERN MATHEMATICS

Exercise 6

交長波

(21)

Answer ALL cuestions in Section A and

any SIX questions in Section B.

18

Section A (Each nuestion carries 4marks)

1. Find all values of 0, 0°£ 0 ≤ 360°

satisfying the equation:** 2cos20+3sin 90

2. Find the value of x if 2log x=

3+310g 2-1og5, base of logarithm

being 10.

3. In figure, the area of quadrilateral "ABCD is enual to 750ad.mp

and AC=2cm.; BD=7cm.

the intersecting angle

between AC and BD.

Find A

B

P is a point on the side AB of square ABCD such that AP-5cm and PBcm, Using four figure tables, find the mea-

of angle DPC.

Bure

A sphere of radius r metres can just be fitted into a cylindrical box whose diameter and height are each 2r metres,

If the empty space between them is 20 cubic metres, find r.

..

6. In figure, AP-2PB,

PO//BC and PR//BQ,

find the ratio

to RC

7. If f(x) =

find f(2). What

number is not in the domain? A. If and are the roots of x-6x+k=0 and o=q+2, find k.

9. The cost of living increases each year by 7 of that of the previous year. If a man lives on $in000 in the first year, how much will be pay for the same living in the fifth year? Give your answer correct to the nearest: hundred dolláre?.......

10. If x =

and y tan A, find the COS A: relation between x and y. Section B (Each nuestion carries 10marke

11a) Prove that __.

+1

b) 3 balls are drawn without replace-

ment from a bag containing 4 black and 6 white balls. If x is a randon variable which denotes the total number of black marbles drawn, com- plete the following table.

* P(X).

.0

1.

→

3

..

Hence, plot » grach with x against the probability P(x),

12. In figure, Ellipse

2

1 cuts Y-axis

9.

at B and D. P(x, B)

is a point on the ellipse. BP and DP cuts the axis

at Q and R respectively.

a) Find the co-ordinates of ✪ and R in

terms of and

b) Show that OQ OR = 25

13. Three numbers are in the ratio:

1:5:19 If 3 is added to each of the numbers, the resulting numbers, will form a geometric progression. Find the original three numbers.

14. In figure, p, a and 7 denotes the vectors AB, BC and CA respectively, find'

a)p-o, d-r and T-p in. terms of the area of

AABC(A), tanh, tan

and tanc

b) Hence or otherwise, if peQ=@•r=r•p

show that ABC is an equilateral tri- angle.

*5, Two kinds of food for horse, Type I

and Type II contain the number of units of protein and carbohydrate per kilogr- ?. am as shown in the table.

Unit of Unit of Car-Cost per Protein bohydrate

kg.

Туре 1 Type II Minimum daily

4 6

16

11

34

$5

If the daily intake from these two foods is to be at least 15 units of protein and 14 units of carbohydrate, what is the most economical way of sat- isfying the condition?

16. In figure, circle CDE

inscribed in the nuard circle AOB, radius 10cm. Find

a) the radius of circle

CDE.

b) the area of the

shaded portion.

17. The cost of digging a hole varies partly as the depth and party as the scuare of the depth, A hole 35m. deep costs $2275 and a hole 50m. deep costs $4000. How deep a hole would be dug for $3375: