Usha Martin World School, Patna
Session: 2016-17
QUESTION BANK
Class: IX
Sub. : CHEMISTRY
All questions are compulsory.
Q1.Calculate the mass of the following:
(i) 0.5 mole of N2 gas (mass from mole of molecule)
(ii) 0.5 mole of N atoms (mass from mole of atom)
(iii) 3.011 × 1023number of N atoms (mass from number)
(iv) 6.022 × 1023 number of N2molecules (mass from number)
Q2. Write down the formulae of
(i) sodium oxide
(ii) aluminium chloride
(iii) sodium suphide
(iv) magnesiumhydroxide
Q3. Which postulate of Dalton’s atomic theory can explain the law of definite proportions?
Q4. If one mole of carbon atoms weighs 12 gram, what is the mass (in gram) of 1 atom of carbon?
Q5. Calculate the number of particles in each of the following:
(i) 46 g of Na atoms (number from mass)
(ii) 8 g O2molecules (number of molecules from mass)
(iii) 0.1 mole of carbon atoms (number from given moles)
Q6. A 0.24 g sample of compound of oxygen and boron was found by analysis to contain 0.096 g of boron and 0.144
g of oxygen. Calculate the percentage composition of the compound by weight.
Q7. Convert into mole.
(a) 12 g of oxygen gas
(b) 20 g of water
(c) 22 g of carbon dioxide
Q8. Calculate the number of aluminium ions present in 0.051 g of aluminium oxide.
Q9. Calculate the molar mass of the following substances.
(a) Ethyne, C2H2
(b) Sulphur molecule, S8
(c) Phosphorus molecule, P4 (Atomic mass of phosphorus = 31)
(d) Hydrochloric acid, HCl
(e) Nitric acid, HNO3
Q10. Define atomicity and its types.
Q11. Explain Rutherford model of atom and its drawbacks.
Q12. Explain Bohr model of atom.
Q13. Explain the discovery of electrons, protons, and neutrons.
Q14. If number of electrons in an atom is 8 and number of protons is also 8, then (i) what is the atomic number of
the atom?
(ii) whatis the charge on the atom?
Q15.Composition of the nuclei of two atomic species X and Y are
given as under X Y
Protons = 6, 6
Neutrons = 6, 8
Give the mass numbers of X and Y. What is the relation between the two species?
Q16.The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes 8X 16and 8
X18 in the sample?
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