Chemistry review for Std IX
I ) The Number of protons, neutrons and electrons in species A to E are given in the
following table.
Species
A
B
C
D
E
Protons
6
18
17
9
17
Neutrons
6
22
20
10
18
Electrons
4
18
17
11
17
Indicate from the above table the species that represents:
i. A cation
ii. An anion
iii. An atom of inert gas iv. A pair of isotopes
II )What is the nature of charge on (i) a cation (ii) an anion?
III )The atomic number of sodium is 11. What is the number of electons in Na+?
The atomic number of chlorine is 17. What is the number of electrons in Cl-?
IV ) What is an ion? State and explain the difference between an atom and the
corresponding ion.
V ) The elements W, X, Y and Z have atomic numbers 7, 8, 9 and 11 respectively.
Write the formulae of the compounds you would expect to form between the following pairs
of elements and indicate the type of bonding present :
i.
W and X
ii. X and X
iii. W and Z
iv. Y and Y
VI ) For three elements X, Y and Z the following data are given:
Element
X
Y
Z
Mass Number
35
23
24
Number of neutrons
18
12
12
Write the chemical formulae of compound (electrovalent /covalent) formed
between:
i.
X and X
ii. X and Y
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iii. Z and X
VII )An element X combines with oxygen to form an oxide X2O. This oxide is
electrically conducting. Give the following information:
i. How many electrons would be there in the outermost shell of the element X?
ii. Write the formulae of the compound which is formed when X reacts with chlorine.
VIII )An element A has four electrons in the outermost shell of its atom and combines
with another element B having seven electrons in the outermost shell of its atom.
The compound formed does not conduct electricity.
What is the nature of the chemical bond in the compound?
IX )An element A forms an oxide A2O5
i. What is the valency of element A?
ii. What will be the formula of chloride of A?
X ) An element A has two electrons in the outermost shell of its atom and combines
with an element B having seven electrons in the outermost shell forming the
compound AB2. The compound when dissolved in water conducts electric current.
Giving reasons, state the nature of chemical bond in the compound.
XI) Elements X is a metal with a valency2.Element Y is anon metal with a Valency 3.
(i)Write equations to show how X and Y forms ions.
(ii) If Y is a diatomic gas write the equations for the direct combination of Xand Y to
form a compound.
XII) Acids dissolve in water and form Hydronium ions draw the structure of the
hydronium.
XIII)Give one Chemical test to distinguish between the following compounds:
i) Ammonium Chloride and Sodium chloride.
ii) Calcium Chloride and Zinc Chloride.
iii) Zinc nitrate and lead nitrate.
iv) Copper sulphate and ferrous sulphate.
v) Zinc Chloride and Lead nitrate.
XIV) The electronic configuration of an element T is 2,8,8,1.
a) What is the group number of T.
b) What is the period no of T.
c) How many valence electrons are there in an atom of T.
d )What is the valency of T.
e ) Is it a metal or a non-metal.
XV) Name the element with
a)Highest Ionisation potential ,Lowest Ionisation potential
b)Highest Electron affinity, Lowest Electron affinity
c)Highest Electronegativity, Lowest Electronegativity
d)Highest Metallic character, Lowest Metallic character
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