育教人工頁三第張八第 日六十月正年未己曆夏
WAH KIU YAT PO
報日僑華
華 勞工處介紹職業
SHEKUJ - SKIPUZKO
請按址往勞工處登記)
-期星
日二十月二年九七九一曆公年八十六國民華中
青女
工你
作狽
15
辦舉
職
項兩
1979
中學會考試題預習專欄
經濟及公共事務 (十八)
明德出版社孔饢璇虛榮俊古嘉利提供資料
Economic & Public Affairs 18
Population
1. Factors affecting the size
*f population
There are a number of factors affecting the size of population of a country.
A group of individuals living in a nation makes up a population of the country. A population is always changing, depending on the rate at which its individual members** reproduce, die or migrate. In other words, the rate birth, rate of death, and rate of migration are the major factors.
the size of B
population. They
described in details as follow (a)Brith rate:
The size:
population is partly
determined by the rate of
1979
中學會考試題預習專欄
化學
(TA)
明德出版社朱宏林提供資料
Chemistry (18)
Solution to Q.25
Gas X is hydrogen and solid Y is sodium ethoxide.
(11) 2CH, CHOI+2Na
CH ONE
(iii)No. of moles of obtained
2240-
22400
= 0.1 moles
According to the equation.
in (ii),
birth of its citizens. A
country with high birth
rate increases its
population size. However,
birth rate is affected by the food supply and the
living enviroment of the
place where they are
situated. A country
having sufficient supply.
s
of food, natural resources, fresh air and clean water and also with good
economic achievement and advanced technical skills usually tends to have a higher birth rate, since the enviroment is favourable enough for the reproduction of human beings. However, in söne under-developed countries, the birth rates are high mainly because an increasing population size can supply more force for their production activities, as long as they are labour-intensive. (b)Death rate: The death. rate of a country depends
labour"
on whether it can introduce nodera
administration improving law and order and eliminating local warfare Also, the introduction
then, in the presence of water vapour, rearts with carbon dioxide in air to form sodium carbonate.
4 Na+
Ne.
02
2NaO
water
A dry mixture of sulphur. dioxide and oxygen is passed over a heated catlyst such as platinum or vanadium(V) oxide. The product is sulphur trioxide.
250.
0 250
(11) A mixture of ethanol and
ethanoic acid is boiled: under reflux with a little of concentrated sulphuric acid as the catalyst. CH COOH+CH OH-
H2O
no. of moles of Na reacted (iii)A dry mixture of nitrogen
no. of moles of H2 x 2
2 x 0.1
0.2
mass of Na reacted
0.2
4.6 g
and hydrogen is passed under Pressure over a heated cata- lyst, iron. The product is ammonia gas. N2+ 3H
2NH
(iv) Molecular mass of ethanol (iv) The water is converted to
According to the equation
13 46.
in (11),
no. of moles of ethanol
reacted
no. of Ne reacted 0.2
mass of ethanol reacted
0.2 x 46
9.2 8
mass of ethanol distilled off
(40 - 9.2) 30.8 g
The ethanol must not be boiled directly with a Bunsen flame, otherwise, the vapour will catch fire readily.
(vi) Ethaol is a covalent com-
pound consisting of molesti cules held together by the weak intermolecular forces while sodium ethoxide (i.......
consist-
solid Y) 15 held together
ing of ions
by the strong electrostatic force. Hence, ethanol has.
a lower boling point than sodium ethoxide.
(vii)The white solid is sodium
carbonate.
When sodium metal is exposed to aib, it is at once öxid- ised to sodium oxide which
of modern transport,
communication, and distribution reduces local famines, Fürthermore, a country introducing public health measurea controlling diseases can reduce, the death rate
Im
(c)Net migration rate: each year, there are sone persona moving into country from another country, and also some persons moving out of a country to live in another country. The former is called inmigration, and the latter is known as emigration. The balance of migration, the difference between imnigration and emigration is added to the size of population of the country. However, the balance of migration does not affect the total population of the world as a whole, Strict immigration lavs: prevent people from moving. freely from one country to another. In this case.
the size of population of a country is largely determined by the death rate and birth rate.
is responsible for the
bleaching action.
H
Ca0012002
Ca CO
As a result, it gradually loses its bleaching power.
(11) The colourless gas is
hydrogen. Copper(II) sul- phate acts aɛ a catalyst in the reaction.
Zn + ,50
(111) Dilute sulphuric acid
steam first. The steam is then passed over the iron. filings at red-hot. The products areiron(II, III)oxide. and hydrogen gas.
3Fe+4H_0(g) →→F¢z0q+4H2
The mixture of sodium sulphite and dilute hydrochloric acid is warmed, The
are modium
sulphur dioxide and water,
Na2SO,+2HC1-
Solution to Q.26
(a) (1)
(1)
(11) Mn: +7 (111) 0.
(iv) ()
Cr: +6 N+5 (vi) C0 (vii) S: +6 (viii) I:45 (1x) N° : -3 (x) Ca: +2
The carbon dioxide and water vapour in air
together react with the bleaching powder to liberate chlárine which
我
To conclude, the
aizé of a country's
population is a combined result of the three rates described above. The size of population can become largeer as the birth rate is greater than the death rate, while the migration is held constant. II. Effects of population
changes The rapid growth of population has posed many prablems on the world as a whole, They are described as follows: (a) The problem of food: An increasing population denands for higher food production. On the other hand, the quality of food and its nutritional value are bath impartant to a country of rising living standards. Thus there may exist a situation in which food is sufficiently supplied in one part of the world while people are starving elsewhere.
(b) The enviroment: Population growth is more or less related to the deterioration of enviromental quality, suck
According to the equation 50*XH2O+2NaOH-⇒
no. of moles of
+(n+2)H2O
x no. of moles of NaOH
used up by compound
- x 0,030
Equating (1) and (2), we have
0.015 moles
2.57
64+18x
0.015
2.57
64+18x=
02015 171.3
171.3-64 18 96
2
Hence, the formula of the compound P 18 SO
consists of hydronium ions H2O which can turn litmus paper red. H2SO +2H 0->2H_0*+so_
However, cone H2SO con- siste manily of covalent molecules and no or little
Besides, hydronium ions. cone H 50 is dehydrating, thus being able to char the litmus paper by removi ing the elements of water
readily.
Glucose is composed of covalent molecules and
lving in water, so its solution does not conduct: electricity. Sodium chlo- ride consists of ions. which become mobile on dissolving in water, 80, its solution can conduct electricity.
Na Cl
water
Na
Solution to Q.
(a)
2+
(1) At the zino rodz
Zn
Zr +2e
At the copper plate :
2e
24
(b)
(1)
when zine dissolves, it leaves behind electrons which then flow from the zinc rod
青 春新
動活
sa air and water.
pollution, depletion of
natural resources,
disppeal of waste
materiala,
An
It makes the Bolations of enviromental problems more difficult. (c) Social problems: increasing population demands for more social services, ranging from education and housing, medical and health, social welfare, to law and order. Besides, the concentration of people in urban areas makes urban planning and administration complex and difficult.
(d) Family health: A family having many children may adversely affect the relation in the family, educational opportunities provided to the children, and also parental care. In turn, these vil1 affect the mental, physical and psychological development of a child. A family of large size usually has unsatisfactory family
and even a relationships deterioration of family life.
sulphate solution will become deeper as there is an increase in the concentration of copper (II) ions.
Mis propan-1-01; Wis pro pene;
X is propanoic acids Y is 1-chloropropane;
Z is sodium propoxide..
--- W: M is heated with conenetrated sulphuric acid fan excess) to 140 c. CH2 CH CH OH – CH2 CH=CH2
→ X: M is boiled under
reflux with acidified potassium dichromate or potassium permangante. CHCH CH2OH + 2(0)
(iii)(1)
to the copper pla (iii)The sulphate ions will pass
of t
out of the porous pote
CH3CH2
COOK+
2
Y: Add phosphorus (V) chloride to M at room temperature.
CH, CHCH OH+PC1-
2
+CH2 CH2 CH2 C1+ POC13 2. Add sodium metal to at room temperature. 2CH CH CHOH 2
2CH_CH CH2ONa + H2
The compound is poly- propylene or poly... propene.
(2) The equation is,
(c)
(1) SO2
Nao + HỘI
042NaOH—⇒ Na2503+
(n+2)H20
H20
(iv) Yes; the colour will become
paler as the copper ions, being responsible for the blue colour, decrease in concentration as the cell(iv) Compound P is 2- operates.
CH, CHCH
CH CHCH
(v)
(24)
Zr
Na CL
Zn
2e
no..
no.
(11) Formula mass of SO, H,
= 32 + 16x2:
6418x
18x
No. of moles of P in 2.57g
2.57
64+ 18x.
According to the equation
#aCH+HIC] Nac1+H2O
noi of moles of Naon left:
no. of moles of He used for neutralization.
1000 = 0.016
1
Original amount of HCI
23
x 2 0.000 0.046 moles
amount of Naoli used by
(0.046-
-0.016) 0.030 moles
According to the equations (v) The equation is
CH, CH-CHHO
Qu
of moles of Zn disolved
of moles of the formed
= 6365
Mass of Zn dissolved
65.3 x
2.06
(vi) The three changes observed
aret M
(1) The current flows in the opposite direction (i.e. electron flows from X to I)
(2) Copper dissolves as it
is more electropositive than silver and silver is deposited at the silver electrode.
(3) The colour of copper(II)
Corrections for Chemistry (13)
There is a mistake in labelling the electrodes in the diagram of Question 19 (b). The diagram and its corrected Fabels are re-printed below for your reference.
carbon
elect- rodes
5M NaC) +1itmeis
411-
battery
Pt elect- Vredes
2M
HSO