第張四藥
九六六年度
日九初月三年午丙曆复
英中會考試題預習專欄
HYATI
英中試題預習專欄
化學科
(十三) ·王錦釗•
物理科 (十三)
陸永熾,
THEMISTRY (13)
(PHYSICS KIN
PURNACE
COMPRE
by Mr. Lux Wing Chee
for resale
You'
ELAQ Fathis
7400°2
DIGALE CUP
વધ
WAS
The sum of reciprocals of the spot distance tuj and the
1.7ge distance (v) 18 equal to tre reciprocal of the focal Lengin of the lens. ~
$
0.23 2.30 25 2.22
2
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x 10 ICA
1.07
2.68
32 3.82 4.13 4.44
4.61
1300
[Ra=> MELTS
1公年五十五國民中
日十三月三年六六九
[HZ-DERHE-EE
對於地公共圖智館,都不斷注會發展公 (按)年來本港,所以,進步的國家,和有關方面自
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提高文化水平
周覺識獲勛街.
公開式供人使用,一
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記
希
VIENO ÁMÉ O MOR!
Path o
0.1 (5). The reactions which take place in a blast furnace z T
summed up as follows:
in the
(1) The oxygen in the blast combines with the ooka
hottest part of the furnace forming carbon monoxide.
2002 - 200 (11) This carbon monoxide rises and reduces the iron oxides'
to rion
70203 300 = 2F* • 3002
Безон • 4CO - 3P + 4002
(111) When the limestone is heated to a temperature above
550°C., it decomposes to form quicklime and carbon dioxide, most of which is reduced by the hot coke to form more carbon monoxide, which in turn reduces more ore to iron.
CB003 • C&O- **
CO2 • C = 200
(iv) The quicklime reacts with the sand and other earthy
material in the ore to form the molten slay, calcium, silicate, which floats on the surface of the molten
fron
(b) Steel is made mainly by two processes: (a) The open hearth' in these processes, 'process, and (b) the Bessemer Process.
the impurities in the cast iron, such as carbon, sulphur, phosphorus and silicon ars converted into oxides, which are them removed as slay by the addition of Limestone. Steels are alloys of iron, The different types of steel are made by adding varying amounts of other metals to th iron, either during the process when the impurities are removed, or subsequently.
(c) Type of Steel
(1) Stainless
steel
(11) Manganese
steal
ii) Tungsten:
steal
Property
Does not rust and of considerable strength.
Very tough
Hard and abrasion- resisting, Remains
"strong and hard"
even at high tem peratures.
Used for making cutlery, and in surgical instru- ment.
Used for making salmiera? | helmets, and in machinery for grinding
Used for making nigh-speed cutting tools,
4.2 is in ure Solvay orocess, salt and limestone are converted indirect,
ly into sodium carbonate and calesum chloride. The process
depends upon the fact that sodium bicarbonate, is only slightly soluble in water.
In practice brine 10 lirat saturated with argonia gas, and carbon dioxide is then bubbled through the solution,
#
NaCl NHLнCO * NaHCO *NHẠC...
(1) (2)
The sodium bicarbonate is precipitated and separated from
the mixture by filtration, and sodium carbonate is then obtained
by nesting the sodium bicarbonate.
• CO2
.(3)
The Limestone is heated in kilns to produce, carbon aloxide
*-**- 2NaHCO3 *
Na2C0; H20
►
and quick lime
CaCO2
CAO 202
(14)
The carbon dioxide obtained in reactions (3) and (4) 20
The quicklime is slaked with water to form slaked fine.
(5) Cao + H2o Ca(OH)2- This slaked lime is heated together with the ammonium »♬ chloride obtained from reaction (2) to produce ammonia.
.(6)
2NHдC1 + Ca(OH)2 CaC12+ 2NHz + 21120....
A constant supply of ammonia is therefore obtained and consequently, after the original charge of ammonia, no other materials are needed, except for salt and limestone.
(b) Put a sample of the salt in an evaporating dish in a desiccato to dry. After a day or two, the dish and its contents are removed from the desiccator and weighed. The dish and its contents are then heated for about fifteen minutes, after
The dish which it is transferred to a desciccator to cool. and its contents are again weighed.
If there is a loss of weight, the sample contains/ sodium bicarbonate..
M
2NaHCO 3 Na2CO3 + CO2 • H2O
The loss of weight is due to the carbon dioxide and water vapour which is given off when sodium bicarbonate is heated. (1)«Putea amall-amount of each solution into four separatemon
test-tubes, and add a little dilute, hydrochloric acid to each. A white precipitate will be formed in one of the test tubes. This test-tube contained the solution of the lead salt. The precipitate formed being lead chloride, PbC12, which is soluble in hot water. but insoluble in.... cold, water. (14) Take, the acidiried solutions of the other three metallic salte, and pass HS into each. A black precipitate will formed in one of the test-tubes. This test-tube contained the solution of the capper salt. Another indication is the colour of the original solution which is blue, copper Balts forming blue-coloured solutions in water. (111) Put a fresh sample of each of the two remaining solution:
into two separate test tubes and add ammonia solution to each. A green or brown gelatinous precipitate will be formed in one of the test-tubes. This test-tube contained I the solution of the iron salt.
(iv) Take the other test-tube and pass Has into the solution in 1
the tube. A white precipitate will be formed, indicating that the test-tube contained the solution of the zing, salt, Questions for next week,
AS
"(8)" "DI WIRE TUNGUMENTAT DETCTelesis atatem,thought-to-be-built up
and how do these differ in mass and electrical change?
(b)) Using calcium chloride and armonia as examples, explain simply
song the difference, between electrovalency and covalency........
(c) What are isotopes? Explain the existence of isotopes in the
the rusting of iron and the means used to prevent t anfict pure anhydrous ferric chloride be made by the the oremation of mast chlorides? How Kasih specimen?.
Reciprocal of Object distance (1 × 10′′)
and I
A = 1.5.
Ano.
The angle of emergence is 40 The lateral displacement is 1.5 cm)
al length of lens
fft.]
bject distance
y ft.
mage distance
v ft.
3
Reciprocal of Image distance {
་
102
ka tha”graph is a straight line, It confirms the relation of
•
The Cool length of the lens Le 15 cm.
- be the sõject distance in om. 1
•
be the. Usage distance in om.
f be the focal length in da.
the limge is daminished to one-third of the object
Я
(1)
In moving the lens 4 ft, towards the wall, a sharp image
As also götäined.
1
•
1
f
1
(2)
V – L
12 - V
Equating (1) and (2)'.
KAME
20 PUBLIC THR
•
3v
and
M
U 30 - V
3v
* 30 - v
3v
- 301
*
☐ 25
W
*
ν
f
નામ મામ
Ans. The focal length of the mirror is 11.25 cm.
refractive index from air to glass
3.
All w
refractive index from air to water
H
2
?
&
3
ell x all m
Aris The refractive index of glass to meter la
Ε
12
V - 4
3
(8 - V). V
-49 →
164 -
J
2
- $1
- 167 43
Substitute into (1)
Ans. The focal length of the convex lens is 15 ft.
Que st Lona (14)
1. (9) Aray of fight travelling in air strikes the surfa
block of glase. It is observed that the angle of ia 27 5. when the angle of Incident is 46° 30% Calculate the refractive index of glase.
(b) another ray makes an incident angle or 60 with the glass block. Calculate the angle of refraction.
() Find the angle of refraction when a ray of light trave 11
on the block makes an angle of 20 at the interface (refractive index = 13)
(d) What is the critical angle for this glass7-
(a) What is the critical angle for glase-water? ·
2. (a) In an experiment to find the refractive index of water
the real and apparent depth method using a vergier microscope, the following readings were obtained a
(1) Reading of microscope focused on coin at bottom of
empty beaker
11.95 cm.
(2) Reading of microscope focused on coin at bottom of
beaker containing water - 9.49 cm..
(3) Reading of imcroscope focused on saw-dust floating on
surface of water.
-$2.11 Co
Calculate the refractive ind
---Light-from-a-luminous-point-on-the-lower-face-of-a-rectangular
glass elab 2 cm, thick strikes the upper face and the totally »»reflected«rays-out-line-australesof--3-2-cm-radius.on.the.
·lower face.
“What lastne rafizctive Indian yn ahəngiase?....