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Class 9 Science chapter 3 atoms and molecules mcqs

                                                                                               Class 9 Science

                                                              Chapter – 3 Atoms and Molecules

(1) The formula of Ammonium Sulphate is —————–

(a) NH4SO4   (b) NH4SO2   (c) (NH4)2SO4   (d) NH2SO4        

(2) Percentage of calcium in calcium carbonate –

(a) 40    (b) 30    (c) 48    (d) 36

(3) The atomic symbol of Iron is —————.

(a) I    (b) Fe    (c) Ir      (d) Au

(4) The formula for aluminium oxide

(a) Al2O3    (b)  AlO    (c) AlO2    (d) Al3O2

(5) Who lead the foundation of laws of chemical combination-

(a) Democritus   (b) Lavoisier   (c) Dalton    (d) proust

(6) Atomic mass of Chlorine is ————– (u)

(a) 34    (b) 34.5     (c) 35        (d) 35.5

(7) Which of the following is the correct pair of atom and its atomic symbol?

(a) Sulphur – Su    (b) Potassium – P  (c) Phosphorus -P   (d) Sodium- S

(8) What is the chemical formula of sodium carbonate?

(a) Na2CO3   (b) NaHCO3   (c) NaCO3    (d) Na2HCO3

(9) The molecule has an atomicity of 4 is –

(a) Sulphate molecule   (b) Ozone molecule   (c) phosphorus  molecule    (d) methane molecule

(10) A box contains some identical red colour balls labelled as A each weighing 2 g. Another box contains identical blue colored balls, labelled as B, each weighing 5 g. In the combinations AB, AB2, A2B and A2B3 which is applicable?

(a) Law of Definite proportion        (b) Law of multiple proportion

(c) Law of conservation of mass  (d) None of the above

(11) Oxygen :  diatomic  : : Ozone :  _______

(a) Monoatomic   (b) diatomic    (c) triatomic    (d) tetra atomic

(12) The atomic symbol of silver is —————

(a) Si   (b) S    (c) Au    (d) Ag

(13) Who coined the term ‘Parmau’ for the smallest invisible particles –

(a) Leucippus   (b) L. Lavoisier (c) Kanad   (d) none of these

(14) When an atom loses electrons, it is called a(an)____  and has a ____ charge

(a) Anion, negative   (b) Cation, positive   (c) anion, positive  (d) cation,negative

(15) Which of the following statements is not true about an atom?
(a) Atoms are not able to exist independently.
(b) Atoms are the basic units from which molecules and ions are
formed.
(c) Atoms are always neutral in nature.
(d) Atoms aggregate in large numbers to form the matter that we can see, feel or touch.

(16) ______ for some items are proposed by Dalton

(a) Shape    (b) Initiator    (c) Symbol    (d) color

(17)  1 u or 1 amu means

(a) 1/12th mass of C-12 atoms   (b) Mass of C-12 atom  (c) Mass of O-16 atom    (d) Mass of Hydrogen molecule

(18) A sample of NHmolecule irrespective of source contains 82.35% Nitrogen and 17.65% of Hydrogen by mass. This data supports:

(a) Law of Conservation of Mass   (b) Las of Multiple Proportions   (c) Law of Definite Proportions   (d) Avogadro’s Law

 (19) An element X is divalent and another element Y is tetravalent. The compound formed by these two elements will be:

(a) XY    (b) XY2   (c) X2Y    (d) XY4

(20) The molecular formula of potassium nitrate is ________.

(a) KNO3    (b) KNO    (c) KNO2      (d) KON

(21) Molecular mass is defined as the:
(a) Mass of one molecule of any substance compared with the mass of one atom of C – 12
(b) Mass of one atom compared with the mass of one atom of hydrogen
(c) Mass of one atom compared with the mass of one molecule
(d) None of the above

(22) A change in the physical state can be brought about
(a) only when energy is given to the system
(b) only when energy is taken out from the system
(c) When energy is either given to, or taken out from the system

(d) Without any energy change

(23) Which of the following represents a correct chemical formula?
(a) CaCl    (b) BiPO4    (c) NaSO4     (d) NaS

(24)  What is the formula mass unit of ZnO?

(a) 18 u    (b) 81 u    (c) 88 u     (d) 188 u

(25) The chemical symbol for sodium is

(a) So    (b) Sd    (c) NA    (d) Na

(26) A change in the physical state can be brought about

(a) only when energy is given to the system

(b) only when energy is taken out from the system

(c) when energy is either given to or taken out from the system

(d) without any energy change

(27) Identify the correct symbol of gold

(a) Ag   (b) Go    (c) Au     (d) AU

(28) The combining capacity of an element is called

(a) Valency   (b) Atomicity   (c) Atomic number    (d) Valence electrons

(29) The balancing of chemical equations is in accordance with

(a) Law of combining volumes    (b) Law of constant proportions    (c)  Law of conservation of mass    (d) Both b and c

(30) Which of the following is the correct statement

(a) Na2S – Sodium sulphide , Na2SO3 – Sodium sulphite, Na2SO4 – Sodium sulphate

(b) Na2S – Sodium sulphite , Na2SO3 – Sodium sulphide, Na2SO4 – Sodium sulphate

(c) Na2S – Sodium sulphide , Na2SO3 – Sodium sulphate, Na2SO4 – Sodium sulphite

(d) Na2S – Sodium sulphite , Na2SO3 – Sodium sulphite, Na2SO4 – Sodium sulphide

(31) The formula of calcium phosphate –

(a) CaPO4       (b) Ca(PO4)2     (c)  Ca3(PO4)2   (d) Ca2(PO4)3

(32) Which of the following is not a postulate of Dalton’s atomic theory –

(a) All matter around us is made up of atoms

(b) Atoms are tiny indivisible and indestructive ultimate particles

(c) Atoms combine in small whole-number ratios to form compounds

(d) Atoms of different elements can have the same mass

(33) An element X has valency equal to 3. What will be its formula with carbonate ions?

(a) X2CO3                 (b) XCO3        (c) X2(CO3)3       (d) X(CO3)3

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