Monday, 13 February 2017

Chemistry Worksheet Class IX For SA2

                                                                 "OM SAI RAM"  
                                     Spectrum Classes
                      Worksheet :- Atom & Molecule
Q.1 The atomic mass of an element is in fraction. What does it mean?
Q.2 Find out the ratio by mass of the  combining elements in the following compounds
(a) MgCO3      (b)CH3OH       (c)CaCl2  (d)NH3
Q.3 Which postulate of Dalton’s Atomic theory is the basis of law of conservation of  mass?
Q.4 What are ions? Its type & the bond formed by ions ?
Q.5 How many moles are present in 11.5 g of sodium sulphate .
Q.6 Difference between molar mass & molecular mass .
Q.7 State and prove law of chemical combination.
Q.8 Is there any exception to law of conservation of mass?
Q.9 If 12 g of carbon is burnt in the presence of 32 g of oxygen, how much carbon dioxide will  be formed?
Q.10 Which has more number number of atoms, 100 grams of sodium or 100 grams of iron
given, atomic mass of Na = 23u, Fe = 56
Q.11Explain postulates of Dalton’s atomic theory &  Drawbacks of Dalton’s Atomic Theory ?
Q.12 The size of sodium atom is bigger than that of hydrogen atom. Why ?
Q.13 Define the following
(a) Atomicity (b) Valency (c) Atomic Number (d) Atomic mass (e) Mass Number
Q.14 Define Isotopes and various isotopes used for different Work .
Q.15 Define Isobars , Isotones , iso electronic species with Example .
Q.16 Define 1 mole of a gas and 1 amu ?
Q.17 Differentiate between atom and molecule.
Q.18 Write Chemical formula for
(a) Potassium carbonate (b) Aluminium hydroxide (c) Ammonium sulphate (d) Carbon tetrachloride
(e) Ammonium carbonate (f) Potassium sulphate (g) Cupric chloride (h) Aluminium nitride (i) Calcium phosphate
Q.19 Calculate the molar mass of the following
substances.
(a) Ammonia (b) Hydrochloric acid (c) Phosphorus molecule (d) Hydrogen molecule (e) Oxygen molecule
(f) Sulphur dioxide
Q.20 Find the number of moles of
 (a) 48 g of oxygen gas (b) 18 g of  H2 O molecules (c) 22 g of CO2 gas (d) 51 g of NH3 gas
Q.21 Calculate the percentage composition of carbon in CO2 .
Q.22 Calculate the number of aluminium ionswhich are present in  0.0051g of aluminium oxide.
Q.23 Calculate the percentage composition of glucose(C6 H12 O6 )
Q.24  When 10g of sulphur is burnt in 10g of oxygen 20g of sulphur dioxide is produced ?  Find the mass of sulphur dioxide formed  on burning 20g of sulphur in 30g of oxygen ? Justify  your answer by stating the law which governs your answer
Spectrum Classes
    Worksheet:- Structure of Atom
Q.1Fill In the Blanks
(a) The electronic configuration of silicon is …………….
(b)  _____ electrons are responsible for the chemical properties of an atom.
(c)  Rutherford’s model of an atom was modified by _______.
(d) ____ is an isotope of carbon used in determining the age of dead plants.
(e)  An atom with 3 protons and 4 neutrons will have a valency of ________
Q. 2The description of atomic particles of two elements X and Y is given below
                                    
 (i) What is the atomic number of Y     (ii) What is the mass number of X
(iii) What is the relation between X and Y   (iv) Which element/elements do they represent
(v) Write the electronic configuration of X    (vi) Write the cation/anion formed by the element
Q.3 (a)Explain Bohr and Bury rules for distribution of electrons into different shells. (b) Draw the electronic structure of element X with atomic number 17 and element Y with atomic  number 16 ?
Q.4 Why is Thomson's model of an atom compared with a watermelon?
Q.5 (i) Why is an alpha particle called a helium nuclei? (ii) What is the charge on the above mentioned particle?
Q.6 Why Rutherford take only gold sheet ? , give any two reason .
Q.7 Why do helium, neon & argon have a zero valency?
Q.8 What are the limitations of J. J. Thomson's model of the atom?
Q.9What are the salient feautres of Bohr's Atomic Model? How is it advantageous over
Rutherford's Nuclear Model?
Q.10 Will Cl -35 and Cl -37 have different valences?
Q.11Calculate the number of neutrons present in the nucleus of an element X which is represented as15 X31 .
Q.12  What were the drawbacks of Rutherford’s model of an atom?
Q.13  Write two differences between isobars and isotopes.
Q.14 When a gold sheet is bombarded by a beam of Alpha particles, only a few of them get deflected whereas most go straight un deflected . Why?
Q.15 Is it possible for the atom of an element to have one electron, one proton and no neutron? If so, name the element.
Q.16 State one use each of an isotope of (i) uranium , (ii) iodine (iii) Carbon (iv) Sodium
Q.17 The electronic configuration of potassium (K) is 2, 8, 8, 1 instead of 2, 8, 9 though the M  shell can accommodate up to 18 electrons. Explain.
Q.18  If chlorine atom is available in the form of two isotopes 17Cl35 (75%) & 17Cl37 (25%)  Calculate the average atomic mass of chlorine atom .
Q.19 (a) Which kind of elements have tendency to lose electron ? Give example .                          (b) What are nucleons ?
Q.20 (a) Write the no. of valence electrons in (a) Na atom and Na+ (b) O atom and O2- (b) An element “E“ loses 2e- to form E+2 ion .What will be the chemical formula of the compound  formed between E and oxygen .
Q.21 Write the electronic configuration of magnesium atom and magnesium ion. How do these configurations differ ? Support your answer in the form of atomic structures .
Q.22 Fill in the Blanks
1. Plum pudding Model of atom was discovered by _______________
2. Combining capacity of an atom is called _______________
3. Alpha particle scattering experiment of Rutherford led to discovery of _________
4. Number of neutrons in is 53 Br 81 _____________
5. __________ are atoms having the same mass number but different atomic number.
6. The charge on the electron is found to be ________ coulombs.
Q.23 What do you understand by valency  of an element? What is valency of boron , Chlorine ,Sulphur & Magnesium ?
Q.24 From what observations do you derive the following inferences?
(i) The most of the space inside the atom is empty.
(ii) The volume of the nucleus is very small.
(iii) Anode rays consist of positively charged particles.
Q.25 Cl- has completely filled K&L shells. Explain.
Q.26 Draw a chart representing Characteristics of the fundamental subatomic particle’s  like mass , charge ,Discovered By Scientist .
Q.27 (a) You are given an element. Find out     
(i) Number of protons, electrons and neutrons in ‘X’.   (ii) Valency of ‘X’.
(iii) Electronic Configuration of ‘X’.  
(b) If bromine atom is available in the form of, say two isotopes 35 (49.7%) and 37 (50.3%). Calculate the average atomic mass of bromine atom.
Q.28 State the problem of atomic structure which was solved after the discovery of neutron.
Q.29 Why Neutron Discovered very Later the discovery of proton ?
Q.30 Give reasons:
(a) Mass number of an atom excludes the mass of an electron.
(b) Nucleus of an atom is charged.
(c) Alpha particle scattering experiment was possible by using gold foil only and not by foil of any other metal.

Spectrum Classes By Er.Shyam Pachori CL 157 D.D Nagar Mob.:9039803981

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