WorksheetsGrade 8 first term
Total questions: 25
Worksheet time: 10mins
The halogen that can replace all the halogens in its salt compound is....................................
chlorine
bromine
fluorine
iodine
Alkali metals are kept under kerosone except..............................is kept under paraffin oil.
sodium
lithium
rubidium
potassium
Who discovered the 7 energy levels?
Mendeleev
Mosely
Bohr
Rutherford
When you put glass bottle filled with water, it explodes. G.R
Because mass increases, so density decreases.
Because density decreases and volume decreases
As temp becomes less than 4 Celsius, crystals of ice are formed which increases the mass
As temp becomes less than 4 Celsius, crystals of ice are formed which increases the volume
The temperature increases in the stratosphere due to.....................................until it reaches....................
oxygen, 0 degree Celsius
ozone, -60 degree Celsius
weather changes, 25 degree Celsius
ozone, 0 degree Celsius
Group 1A is called..................................while group zero is...............................
alkali metals and halogens
If the temperature at the sea level is 20 degree Celsius, find the temperature of a top of mountain of a height of 5000 m.
-12.5 degree Celsius
-32480 degree Celsius
When magnesium react with dilute HCl, it produces..............................which is..............................
MgCl, a salt
MgO, a base
MgH2, an acid
MgCl2, a salt
Silicon is used in electronic devices such as computer because it is................................
Due to low boiling point of -196 degree Celsius
a semiconductor material that conducts electricity while changing temperature
Sodium fires cannot be extinguished using water. (Give reasons)
(Write the equation)
Because water is good conductor of heat
Na+O2=Na2O
Because water reacts with sodium producing hydrogen that burns with pop sound.
na+h2o=naoh+h2
Because water reacts with sodium producing hydrogen that burns with pop sound.
2Na+2H2O=2NaOH+H2
Because water is good conductor of heat
Na+HCl=NaCl+H2
What is the atomic number of element lies in period 2 group 7?
The layer of the atmosphere that protects the Earth from celestial rocky masses contains.............................and.............................gases only.
ozone and helium
carbon dioxide and hydrogen
oxygen and ozone
The metallic property................................as we go in the same period.
This phenomena is named as........................and it happens when charged cosmic radiations collides with....................................
aurora, mesosphere
van allen, ozone
aurora, Van Allen belts
aurora, ionosphere
Halogens are named like this because they reacts with metals forming.....................................
The ozone layer extends from............to.........................km in the stratosphere layer.
5 to 25
20 to 40
15 to 35
10 to 30
In electrolysis of water,.............................is produced at the cathode of Hoffmann voltmeter
Which of the following has zero electronegativity?
Na 11
Ar 18
F 9
Ca 20
The separation of oxygen from sea water and death of marine creatures is classified as......................................pollution.
chemical
radiant
biological
thermal
Sugar can dissolve in water because..............................................
sugar molecules have high density than water
sugar molecules are ionic compounds
sugar molecules can form hydrogen bonds with water molecules
.........................................is used to determine the day weather.
Altimeter
Aneroid
Hoffmann voltmeter
Van Allen
While putting cesium and potassium in water,................................sinks due to............................density.
cesium, low
potassium, high
cesium, high
potassium, low
When dissolving MgO in water, the litmus paper changes into blue beacuse..............................
MgO and water are acidic solutions
MgO is a non metal oxide that gives acidic solution
MgO is an basic oxide that gives alkaline solution
water changes litmus paper to blue
The largest atomic size of these elements is..........................................
Na 11
O 8
Li 3
N 7
According to chemical activity series, this arrangement is true?
K, Na, Mg, Zn, Ca, Fe, Cu, Ag
