science preparatory 2 Final revision
science preparatory 2 First Term
[1]Give reasons with answers 2023
1 -Many attempts are made by scientists for classification of elements.
– To be easily studied and to find the relation between elements and their physical and <a href="https://gogoacademy.net/science-for-primary-4th-final-revision-for-primary-4/">chemical</a> properties.
2 – Failure of Mendeleev’s periodic table (Appearance of Mosley’s periodic table).
Because there were some disadvantages such as:
A- Make disturbance in the ascending order of atomic weights for some elements.
B- Dealing with isotopes of one element as different elements.
3 -Mosley arranged the elements according to their <a href="https://gogoacademy.net/science-prep-1-final-revision/">atomic number</a> not their atomic weight.
Because he found that the periodicity of the elements properties is related to their atomic numbers not their atomic weight.
4 -Element (11Na) lies in the first group, while element (13 Al) lies in the third group.
Because the no. of <a href="https://gogoacademy.net/science-prep-1-final-revision/">electrons</a> in the outer most shell for (Na) = 1
And the no. of <a href="https://gogoacademy.net/science-prep-1-final-revision/">electrons</a> in the outer most shell for (Al) = 3
5 – Knowing the <a href="https://gogoacademy.net/science-prep-1-final-revision/">atomic number</a> for the element allowing determining its location in the periodic table.
Because number of <a href="https://gogoacademy.net/science-prep-1-final-revision/">energy</a> levels indicates the period, while number of outer most <a href="https://gogoacademy.net/science-prep-1-final-revision/">electrons</a> indicates the group.
6 – The atomic size decreases in the period by the increase of the <a href="https://gogoacademy.net/science-prep-1-final-revision/">atomic number</a>.
– Due the increase of the attraction force between positive nucleus and the <a href="https://gogoacademy.net/science-prep-1-final-revision/">electrons</a> in the outermost <a href="https://gogoacademy.net/science-prep-1-final-revision/">energy</a> level.
7 -The atomic size increases in the same group by the increase of their atomic numbers.
– Due to the increase in the number of <a href="https://gogoacademy.net/science-prep-1-final-revision/">energy</a> levels in the <a href="https://gogoacademy.net/science-prep-1-final-revision/">atom</a>.
9 -water and ammonia are polar compounds.
Because the electronegativity difference between their elements is relatively high.
11 -It is difficult to identify semimetals by knowing their electronic configuration.
Due to the difference of numbers of the <a href="https://gogoacademy.net/science-prep-1-final-revision/">electrons</a> in their valence shells.
12 -Metallic property of the same group increases by the increase of the <a href="https://gogoacademy.net/science-prep-1-final-revision/">atomic number</a> as we go from up to down.
Due to the increase of the atomic size.
13 -Non-metallic property decreases in the group as in (7A).
Due to the decrease of electronegativity values.
15 -The metals of group (1A) are called alkali metals.
Because they react with water forming alkali solutions.
16 -Although Hydrogen gas exists in group (1A) it is a non-metal.
Because its <a href="https://gogoacademy.net/science-prep-1-final-revision/">atom</a> is remarkably small and it is a gaseous element.
17 – Some of alkali metals are kept under kerosene or paraffin.
To prevent their reaction with moist air.
18 – Lithium is kept under Paraffin not kerosene.
Because it floats on the surface of kerosene and it is immediately burns.
19 -water which used in the cooling of the nuclear reactors destroys the marine organisms found in it.
Due to the separation of the dissolved oxygen in it.
20 – Alkali metals are monovalent elements.
Because they contains one electron in the outer most <a href="https://gogoacademy.net/science-prep-1-final-revision/">energy</a> level.
21 -Earth alkaline metals are divalent elements.
Because they contains two <a href="https://gogoacademy.net/science-prep-1-final-revision/">electrons</a> in the outer most <a href="https://gogoacademy.net/science-prep-1-final-revision/">energy</a> level.
23 -the <a href="https://gogoacademy.net/science-for-primary-4th-final-revision-for-primary-4/">chemical</a> activity of group 2A elements increases by the increase of the atomic size.
Because the loss of valency <a href="https://gogoacademy.net/science-prep-1-final-revision/">electrons</a> become easier.
24 -elements of group (17) are called Halogens.
Because they react with metals forming salts.
2K + Br2 2 KBr
26 -elements of group (17) are monovalent elements.
Because they gain one electron during the <a href="https://gogoacademy.net/science-for-primary-4th-final-revision-for-primary-4/">chemical</a> reactions
27 -elements of group 17 don’t exist individually.
Because they are chemically active.
28 -Sodium is used in its liquid state as it is a good conductor of heat.
Because it is used in the transferring heat from inside the nuclear reactor to outside.
29 -Silicon slides are used in the manufactures of computers .
Because they are semiconductors which their conductivity of electricity depends on the temperature.
30 -Liquified Nitrogen is used in the preservation of cornea.
Because it has a very low boiling point (-196° c).
31 -The radioactive cobalt is used in food preservation.
Because gamma rays which comes out from it prevent the reproduction of microbial cells.
32 -A weak electrostatic attraction originated between water molecules which are called hydrogen bonds.
Due to the large electronegativity of oxygen compared with hydrogen.
33 -The abnormality of water properties.
Because of the presence of hydrogen bonds between its molecules.
34 -water is a unique substance.
Because its existence in the three states at the ordinary temperature.
35 -Rising of the boiling point of water.
Due to the presence of hydrogen bonds.
36 -The density of water when it is in solid state is lower than when it is a liquid state.
Because when it is in the temperature lower than 4 ° c, the water molecules are collected by hydrogen bonds forming hexagonal crystals with many spaces between them.
37 -Swimming in the sea is easier than swimming in the pole.
Because the density of salty water is higher than density of the fresh water.
40 -water is neutral liquid.
Because when it is ionizes it gives equal numbers of positive hydrogen ions and negative hydroxide ions. (H+ = OH -).
41 -Mixing human and animal wastes of water cause many diseases.
Because it cause the biological pollution which makes (Bilharzia – typhoid – hepatitis)
42 -Importance of aneroid barometer.
To estimate the day weather and atmospheric barometer.
43 -Troposphere is called disturbed layer.
Because most of the weather changes takes place in it.
44 -All atmospheric phenomena like rains, winds and clouds takes place in troposphere.
Because it contains about 75% of the atmosphere <a href="https://gogoacademy.net/science-prep-1-final-revision/">mass</a>.
45 -Earth’s atmosphere is organized by the 1st atmospheric layer (troposphere).
Because it contains about 99%of the atmospheric water vapour.
46 -At the lower part of the stratosphere, the temperature measures (– 60º C), then increases gradually until it reaches 0º C at the end of the layer.
Due to the absorption of ultraviolet <a href="https://gogoacademy.net/science-prep-1-final-revision/">radiation</a> (emitted from The Sun) by the ozone layer that is present in the upper part of the layer.
47 -The lower part of stratosphere is suitable for flying planes.
Because it doesn’t contain clouds or any weather disturbances and the air moves in this part horizontally.
48 -Although meteors burn in the mesosphere, space ships don’t burn during passing through it.
As they have a conical front that disperses heat and tails made of an insulated material.
49 – Mesosphere layer is much vacuumed.
As it contains only a limited amount of <a href="https://gogoacademy.net/science-prep-1-final-revision/">helium</a> and hydrogen gases.
50 – Meteors burn in mesosphere layer.
Due to friction with air molecules.
51 – Thermosphere means the heated layer.
As it is the hottest layer of the atmosphere.
52 – Ionosphere plays an important role in wireless communication and broadcasting.
As it reflects radio waves that are transmitted by communication centers and radio stations.
53 – Ionosphere is surrounded by two magnetic belts known as Van Allen Belts.
Because these two belts scatter harmful charged cosmic <a href="https://gogoacademy.net/science-prep-1-final-revision/">radiation</a> away from the Earth.
54 – Ozone layer is formed in the stratosphere.
Because it contains a suitable amount of oxygen gas.
55 -Important of ozone layer (Ozone is said to act as a protective shield for living organisms).
Because it does not allow penetration of all far and medium ultraviolet radiations, which have very harmful effects.
56 -Ultraviolet radiations, of wavelength close to the visible light penetrate the atmosphere and reach the earth’s surface.
Where it helps in producing Vitamin D in the bodies of the newly born babies.
57 -Ozone Hole increases in September each year.
Because all pollutants are assemble as black clouds that are pushed by the wind towards South Pole.
58 -Use of chlorofluorocarbon compounds must be reduced.
Because they erode the ozone layer.
59 -stop producing the ultrasound concord planes.
Because their exhausts affects the ozone
60 -The temperature of the planet earth has been increased.
Due to the greenhouse gases in the atmosphere.
62 -Altimeter is used in airplanes.
To determine the elevation of navigation based on the atmospheric pressure.
63 -The difference between cast and mold fossils.
Cast: gives the internal details of the living.
Mold: Gives the outer details of the living.
64 -The importance of the index fossil.
It indicates the age of sedimentary rocks and help in petroleum exploraton
[2]What Is The Function Of The Following?
1- Bohr:
2-Mendeleev:
3-Moseley:
4-Modern Periodic Table:
5-Liquified Sodium:
6-Cobalt 60:
7-Silicon:
10-Hydrogen Bond:
11-Low Density during Water Freezing:
14-Hofmann S Voltmeter:
15-Tropospher:
16-Stratospher:
17-Mesospher:
18-Thermoshere:
19-Ionosphere:
20-Exosphere:
21-Satellite:
22-Van-Allen Belts:
23-Ozone Layer:
24-Dobson Unit:
25-Barometer Instrument:
26-Aneroid Device:
27-Map of Atmospheric Pressure:
28-Altimeter Set:
29-Freon (Chlorofluorocarbon) (CFC):
30-Halons:
31-Methyl Bromide Gas:
32-Montreal Protocol:
33-Kyoto Protocol:
34-Fossils:
35-Coral Fossils:
36-Nummulite Fossils:
37-Ferns Fossils:
38-Snow & Amber:
39-Natural Protectorate:
40-Horns of Rhinoceros:
41-Bluestone Protectorate:
42-Panda Protectorate:
43-Ras Mohamed Protectorate:
44-Wadi-Hetan Protectorate:
45-(IUCN) Society:
46-Micro-Fossils:
48-Electronegativity:
49-Bicometer:
[3] Problems of atmospheric pressure:
1) Temp. At top = temp. At down – (height × 6.5)
2) Temp. At down = temp. At top + (height × 6.5 )
3) Height = temp. at down – temp. at top /6.5
1- Find the temperature at a point of height 10000 meters above sea level if the temperature at sea level is 24°C.
2- Find the temperature at a point of height 2000 meters above sea level if the temperature at sea level is 23°C.
3- If the temperature at sea level is 24.5°C, find the temperature at the top of troposphere layer if its thickness is 13 kilometers.
4- Calculate the height of a mountain if the temperature at its base is 30°C and at its top is (— 9°C).
[4])Complete:
1- lithum and sodium ……. On the surface of water as their densities are …. than water density.
2-water is a good polar …….. as it has the ability to dissolve most ……. Compounds
3-……. Is the second atmosphere layer and it is also called the…….
4-…….. is surrounded by two magnetic belts known as ……
5-In Moseley s periodic table the <a href="https://gogoacademy.net/science-prep-1-final-revision/">atomic number</a> of each element increases by ……… from the element before it in the same …………..
6-…….. trees secrete resinous matter which changes into …….. after solidification.
7- ……. Are safe areas established to protect endangered <a href="https://gogoacademy.net/science-prep-1-final-revision/">species</a> in their homeland.
8-……….. originated from mixing of human and animal wastes with water causing many diseases .
9- The scientist ……………. Discovered the main <a href="https://gogoacademy.net/science-prep-1-final-revision/">energy</a> levels
10-The …………. is the unit used to measure the atomic size .
11- MgO + H2O ……………….
12- The bond between oxygen and hydrogen in water molecule is …………..
13-The layer of atmosphere which contains ozone layer is called ………..
14-The main cause of extinction of Dodo bird is ………….
15-The d-block contains ……… elements .
16- 2H2O ………….. + ……………………
17-Magnesium reacts with hydrochloric acid giving ………… and …………….
18-increasing the concentration of mercury in drinking water causes ………. While …………..increases the infection rate by liver cancer.
19-The measuring unit of atomic size …………
20-The satellite revolve around the earth in a region called ………….
21- ………….. has a wolf s , head ,dog s tail and tiger s skin
22-The modern periodic table consist of ………. Horizontal periods and …….. vertical groups.
[5] Compare between :
1-Elements of group 1A , 2A related to (Name- valency – density – kind of ions)
2-mesospher and troposphere in terms of temperature and structure
3- mammoth and amber fossil
4-Altimeter and aneroid
5-Cathode and anode in Hofmann s voltameter (the type of evolved gas at the 2 poles)
6- Moseley s P.T and Mendeleev s P.T (concepts of arrangement elements)
7-troposphere and stratosphere( temp, pressure )
8-Thermosphere and mesosphere (height – temp)
[6]Locate the position of an element its <a href="https://gogoacademy.net/science-prep-1-final-revision/">atomic number</a> is 17 then:
a-find the <a href="https://gogoacademy.net/science-prep-1-final-revision/">atomic number</a> above it in the same group
b-write the name of the group in which both of them are present
[7] what is the importance ?
1-foraminifera fossil
2-silicon element
3-Liquified Sodium:
4-Cobalt 60:
5-Silicon:
6-Hydrogen Bond:
7-Hofmann S Voltmeter:
8-Satellite:
9-Van-Allen Belts:
10-Ozone Layer:
11-Dobson Unit:
12-Barometer Instrument:
13-Aneroid Device:
14-Map of Atmospheric Pressure:
15-Altimeter Set:
16-Freon (Chlorofluorocarbon) (CFC):
17-Halons:
18-Methyl Bromide Gas:
19-Montreal Protocol:
20-Kyoto Protocol:
21-Fossils:
22-Coral Fossils:
23-Nummulite Fossils:
24-Ferns Fossils:
25-Natural Protectorate:
26-Horns of Rhinoceros:
27-Bluestone Protectorate:
28-Panda Protectorate:
29-Ras Mohamed Protectorate:
30-Wadi-Hetan Protectorate:
315-Feron:
32-Micro-Fossils:
[8] How can you explain:
- Presence of Nummulite fossils in desert environment
- Occurrence of Aurora phenomenon
- Atomic size increases from up to down in the group
- Cutting tress may lead to global warming
[9]What happens when ?
- Sorting water in plastic bottles
- Increasing the ratio of greenhouse gases in atmosphere
- The temperature of water becomes less than 4
- The harmful ultraviolet rays affect the human
- Adding dil HCL to a piece of <a href="https://gogoacademy.net/science-prep-1-final-revision/">copper</a>
- Dipping old <a href="https://gogoacademy.net/science-prep-1-final-revision/">insects</a> in amber
- Decrease of water temperature to 4 c
- Dissolving magnesium oxide in water (write the balanced equation)
- Melting of ice of both poles
- Increasing the ratio of nitrogen oxides in the atmosphere
- Passing of electric current through Hofmmans voltameter containing acidic water
- Throwing detergents in water
- -The low rate of reproduction of passenger pigeon
[10]Mention the difference between
- the cast and the trace
- the simple ecosystem and the complicated ecosystem
- traces and remains
- near and far ultraviolet rays
- basic oxides and acidic oxides
- fluorine molecule and <a href="https://gogoacademy.net/science-prep-1-final-revision/">helium</a> molecule
[11] mention an example ?
1-A very active metal
2-an endangered animal
3-An extinct animal
4-polar compound
5-fossils of complete body
6-chemical water pollutants
7-greenhouse gases
8-basic oxide
9- an element that has the highest electronegativity
10-An animal habitats bamboo forests
11-A microscopic fossil
12-An endangered bird
13-A pollutant of ozone layer
14- a metalloid element
[12]Choose the odd word out then mention what the rest has in common:
1-methyl bromide – Halons – nitrogen oxides – carbon dioxide
- mesopause – stratopause – stratosphere – tropopause
- Trilobite fossils – nummulites fossils – fossils of <a href="https://gogoacademy.net/science-prep-1-final-revision/">ferns</a> – Ammounites fossils
[13]What is the results of each of the following ?
- Absence of ozone layer
- Burning of magnesium strip in the presence of o2 gas (show by equation)
[14]Explain the behavior of water with
- Iron
- potassium
- Sodium
- Zinc
[15]Write short notes about each of the following:
- Reasons of recent extinction
- Different types of ecosystem with examples
[16]What are the consequence of the following :
1-the pollution of water with animals and human wastes
2-Mineral salts replace the organic matter of dinosaurs eggs
17)Problem:Element Y18 in a periodic table find:
1-Its electronic configuration 2- its group 3- its period
2-locate the position (group – period –block) of element 7X and find the <a href="https://gogoacademy.net/science-prep-1-final-revision/">atomic number</a> of the element follows this element in the same group
3-if the temp. at the foot of mountain is 35 c find the temp. at height 300 m above the earths surface
4-calculate the height of a mountain if the temperature at it foot is 20 c and its top is -6c
5-Illustrate with fornula only the role of ultraviolet in formation of ozone gas
18)What is meant by (define )?
1- Electronegativity:
The ability of the <a href="https://gogoacademy.net/science-prep-1-final-revision/">atom</a> in covalent molecule to attract the <a href="https://gogoacademy.net/science-prep-1-final-revision/">electrons</a> of the bond towards itself.
2- Polar compound:
They are covalent compounds in which the difference in electronegativity between elements forming their molecules is relatively high.
4- <a href="https://gogoacademy.net/science-for-primary-4th-final-revision-for-primary-4/">Chemical</a> activity series:
series in which metals are arranged in a descending order according to their <a href="https://gogoacademy.net/science-for-primary-4th-final-revision-for-primary-4/">chemical</a> activity.
5- Hydrogen bond:
Weak electrostatic attraction force that arises between the molecules of polar compounds.
10- Hofmann’s voltammeter:
An apparatus used for the electrolysis of acidified water.
11- Water pollution:
The addition of any substance to the water which causes continuous gradual change in water properties and affecting the health and the life of living creatures.
12- Metalloids [Semi – metallic elements]:
They are elements which have the properties of both metals and non metals.
13- Atmospheric envelope of earth:
It is gaseous envelope rotating with the Earth around its axis and it extends about 1000 km above sea level.
14- Atmospheric pressure:
The weight of air column of an atmosphere height on a unit area (1 cm2 or 1 m2)
16- Isobar:
curved lines that join the points of equal pressure in atmospheric pressure maps.
17- Tropopause:
The region between troposphere and stratosphere.
18- Stratopause:
The region between stratosphere and mesosphere.
19- Mesopause:
The region between mesosphere and thermosphere.
20- Ionosphere layer:
The layer that contains charged ions and it has an important role in wireless communications.
21- Van Allen belts:
They are two magnetic belts surrounding ionosphere and play an important role in scattering of harmful charged cosmic radiations.
22- Aurora phenomenon:
A phenomenon that appears as brightly coloured light curtains seen from the both poles (North and south) of the Earth.
23- Exosphere:
Region in which the atmospheric envelope is inserted with outer space.
24- Erosion of ozone layer:
Losing parts of ozone layer (become thin).
25- Global warming phenomenon:
Continuous increase in the average temperature of the earth near surface air.
26- Green house effect: T
rapping of infrared <a href="https://gogoacademy.net/science-prep-1-final-revision/">radiation</a> in the troposphere layer due to increase of ratio of greenhouse gases which cause the increase of planet Earth temperature.
27- Fossils:
They are traces and remains of the old living organisms that are preserved in sedimentary rocks.
28- Trace:
They are traces indicate the activity of once an old living organisms during its life.
29- Remains:
They are parts indicate the remains of once old living organisms after death.
30- Amber:
The resinous mater is secreted from pine trees and had been solidified and preserved the bodies of organisms from decaying.
31- Solid cast:
It is replica of the internal details of a skeleton of once an old living organism.
32- Mold: It is replica of the external details of a skeleton of once an old living organism.
33- Petrified fossils:
They are fossils in which minerals replace the organic matter for organism part by part leaving the shape without any change.
34- Petrified woods:
They are fossils which are formed as a result of replacing the organic matter of wood by silica part by part and they give us details about the life of once an old plant.
35- Petrification:
It is the process of replacing wood material of trees by silica to form petrified woods part by par.
36- Index fossils:
They are fossils of the organisms that lived a short period of time in the past and had a wide geological distribution and became extinct.
37- Fossil record:
The fossils that exist in the rocks of different areas that indicate the extinction and evolution of organisms.
38- Extinction:
It the continuous decrease without compensation in the number of a certain <a href="https://gogoacademy.net/science-prep-1-final-revision/">species</a> of living organisms until all members dies out.
39- The moment of extinction:
It is the date of death of last individual of that <a href="https://gogoacademy.net/science-prep-1-final-revision/">species</a>.
40- IUCN:
The International Union for Conservation of Nature, was established to protect the endangered <a href="https://gogoacademy.net/science-prep-1-final-revision/">species</a>.
42- The simple ecosystem:
It is ecosystem that has a few members and it is affected by the absence of one type of <a href="https://gogoacademy.net/science-prep-1-final-revision/">species</a> of organisms.
43- The complicated ecosystem:
It is ecosystem that has multiple members and it is not affected much by the
absence of a <a href="https://gogoacademy.net/science-prep-1-final-revision/">species</a> of the living organisms.
45- Natural protectorates:
They are safe areas established to protect endangered <a href="https://gogoacademy.net/science-prep-1-final-revision/">species</a> in their homeland.
