QUESTION BANK SAII CLASS9
1 Name any two noble gases.
1 Name any two noble gases.
2. Write the chemical symbols of the following elements :
Gold, Copper, Potassium, Silver, Platinum and Iron
3 (a) Derive the
valency of an element having atomic number 5.
(b) Name the subatomic particle whose number is not same in
isotopic species of an element.
(c) Name the element
which has no neutron in its atom.
4. An atom contains 3
protons, 3 electrons and 4 neutrons. Find its atomic number, mass number and
valency ?
5. (a) Define one mole, illustrate its relationship with
Avogadro Constant.
(b) Calculate the
number of moles in :
(i) 12.044 3
1023 atoms of carbon.
(ii) 64 g of oxygen
atoms.
(iii) 66 g of carbon dioxide molecules ( atomic masses O=16,
C = 12 )
6. In a chemical reaction between sodium sulphate and barium
chloride, precipitate of barium sulphate is formed. The colour of the
precipitate is : (a) Pink (b) White (c) Orange (d) Yellow
7. Which of the following reaction is not suitable to verify
the law of conservation of mass in a chemical reaction ? (a) Precipitation
reaction (b) Displacement reaction (c) Redox reaction (d) Nuclear reaction
8.(a) Why did Rutherford select gold foil for his
molecule a-particle
scattering experiment
(b)Write
difference between O2 and 2O.
(c) Give one example in each of the following cases : (i)
Monoatomic molecule (ii) Diatomic molecule (iii) Tri atomic molecule (iv)
Tetraatomic?
9.(a) Which of the following species have 18 electrons ?
Ca+2 , K+
, Na , Cl- , Ar
(b) Chemical properties of all the isotopes of an element
are similar. State reason
10.. Define the following terms : (a) Atom (b) Molecule (c)
Avogadro’s number (d) Valency (e) Molar mass
11. In order to verify the law of conservation of mass, we
carry out chemical reactions in a closed container, so that
(a) gaseous products
do not escape
(b) heat transfer
does not occur
(c) reactants do not mix with the products
(d) none of the above
12. On heating 60 g of Calcium carbonate 26.4 g of carbon
dioxide escapes. What will be the amount of residue left ? (a) 33.6 g (b) 12.6
g (c) 86.4 g (d) 26.4 g
13. An element X has a valency of 2. Write the formula of
its oxide?
14. One element has atom with 15 electrons. (2) a) Draw a
diagram to show the electron distribution
b) Write the
electronic configuration in its -3 ion state.
c) Name the element.
15. .a) Calculate the number of Aluminium ions in 0.051 gms
of Al2O3. (Atomic mass of Al = 27u, O = 16 u, NA = 6.022 x 1023 mol-1 ). .
Sol. Molecular weight
of aluminium oxide = 2x 27+3 x16 =54 +48 =102 g/mol
102 g of Al2 O3
contains 2x 6.022 x10 23
Al3+ ions 0.051 g of Al2 O3 contains= 2x 6.022 x10 23 Al3+
ions
6.022 x 10 20 Al3+ ions
b) Name the elements
present in baking soda.
16. .Which of the following are isotopes and which are the
isobars? Argon, Protium, Calcium, Deuterium Explain why the isotopes have
similar chemical properties but they differ in physical properties?
Sol. Chemical
properties of isotopes are same because they have same atomic number and hence
same no. of valence electrons.Physical properties differ because they have
dfferent mass number.
17. Enlist the conclusions drawn by Rutherford
from his alpha-ray scattering experiment
18. Write the
chemical formulae of : i) Calcium Phosphate ii) Ammonium hydroxide
19. Calculate:- (a) The
mass of 1.0505 x 1023 molecules of carbon dioxide (CO2)?
(b) The number of molecules of 0.25 moles of NH3?
(c) The formula unit mass of Na2SO3. (Atomic Mass : Na = 23
u, S = 32 u,C=12u, N=14u, O = 16 u, H = 1 u, NA = 6.022 x 1023 mol-1 )
20. When we make copper sulphate and sodium carbonate react
to prove law of conservation of mass. The product formed will be:
(a) copper carbonate
and sodium carbonate. (b) copper carbonate and sodium sulphate.
(c) copper sulphate
and sodium sulphate. (d) copper sulphate and sodium carbonate.
21 Define the term atomic mass unit
22. .What is the number of electrons in Ca and Ca+2. Write
their electronic configuration?
23. .Differentiate between isotopes and isobars giving
one example of each? Why do isotopes show similar chemical properties?
24..(a) State any two Bohr's postulates about the model of
an atom?
(b) Write the electronic configuration of an
atom whose atomic number is 19 and mass number 39.
Write the number of protons and the number of neutrons present
in it.
25. a) Calculate the number of atoms in 120 gms of Calcium
and 120 gms of iron.Which one has more number of atoms and how much is the
difference.(Given : Calcium = 40 u, Iron = 56 u)
b) Write the chemical
formulae of: i) Hydrogen Sulphide ii) Ammonium Carbonate
26. When we react lead nitrate and sodium chloride to get
lead chloride and sodium nitrate so as to prove law of conservation of mass,
which of the following statements is correct:-
(a) Mass of lead
nitrate = Mass of sodium chloride
(b) Mass of lead
nitrate + Mass of sodium chloride = Mass of lead chloride + Mass of sodium
nitrate.
(c) Mass of lead
chloride + Mass of sodium chloride = Mass of lead nitrate + Mass of sodium
nitrate.
(d) Mass of sodium
chloride + Mass of sodium nitrate = Mass of lead chloride + Mass of lead
nitrate
27. (a) Define polyatomic ion.
(b) Write the name of the compound (NH4 )2
SO4 and mention the ions present in it.
28. (a) Derive the valency of an element having atomic
number 5.
(b) Name the subatomic particle whose number is not same in
isotopic species of an element.
(c) Name the element
which has no neutron in its atom.
29. Name any two noble gases
.
30. Write the chemical symbols of the following elements :
Gold, Copper, Potassium, Silver, Platinum and Iron
31. (a) Write two points of difference between an atom and
an ion.
(b) Calculate the number of moles in :
(i) 12.044 3 1023 atoms of carbon.
(ii) 64 g of oxygen
atoms.
(iii) 66 g of carbon dioxide molecules ( atomic masses O=16,
C = 12 )
32. For the following chemical equation, if the law of
conservation of mass is correct, what would be the number of H2 molecules ? N2+H2®2NH3
(a) 2 (b) 3 (c) 4 (d)
6
33. If the law of
conservation of mass is correct then what are the number of molecules of KCl
and oxygen obtained in the following reaction ? 2KClO3® KCl + O2
(a) KCl=2, O2=2 (b) KCl=1, O2=3 (c)
KCl=2, O2=3 (d) KCl =3, O2=2
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