CBSE Questions for Class 9 Chemistry Atoms And Molecules Quiz 2 - MCQExams.com

Which scientist suggested that the symbols of elements should be made of one or more letters of the names of the elements?
  • Dalton
  • Rutherford
  • Lavoisier
  • Berzelius
What is the atomic mass (u) of sodium?
  • 22
  • 23
  • 23.5
  • 24
The sum of mass of all the atoms in a molecule is known as :
  • molecular mass
  • mass number
  • atomic weight
  • None of above
Atoms of same element combines to form:
  • molecules
  • ions
  • large atoms
  • compounds
The unit, mole, was accepted in the year?
  • 1962
  • 1965
  • 1967
  • 1969
A negatively charged ion in a compound is called a/an:
  • electron
  • valency
  • cation
  • anion
The word mole was introduced by ______  in _______.
  • Avogadro, 1897
  • Dalton, 1896
  • Wilhelm Ostwald, 1896
  • Proust, 1897
One mole is equal to number of atoms as contained in:
  • 1 g of carbon
  • 6 g of carbon
  • 12 g of carbon
  • 12 kg of carbon
The symbol of potassium is taken from :
  • kalium
  • kappa
  • kamenikeia
  • kassandrenos
French chemist ____ laid the foundation to the scientific investigation of matter by describing that substances react by following certain laws.
  • Dalton
  • Rutherford
  • Antony van Leeuwenhoek
  • A. Lavoisier
The laws of chemical combination formed on the basis of :
  • Dalton's atomic theory
  • Dalton's mass theory
  • Both A and B
  • None of the above
The correct symbol of metal cobalt is:
  • $$Sd$$
  • $$De$$
  • $$Co$$
  • $$Pn$$
Atoms are:
  • indivisible
  • divisible
  • may be divisible
  • None of the above
The word 'atom' is derived from the Greek word ____________.
  • atomic
  • atomos
  • atomey
  • atomoney
_____ are the basic units of matter and the defining structure of elements.
  • Compounds
  • Atoms
  • Ions
  • None of these
........... are made up of atoms that are held together by chemical bonds.
  • Elements
  • Molecules
  • Mixtures
  • Both A and B
Definition of anion is :
  • Negatively charged ion
  • Positively charged ion
  • Neutral ion
  • None of the above

The discovery of __________ proved that atom is divisible.
  • atoms
  • sub-atomic particles
  • elements
  • isotope
What is a molecule?
  • A group of two or more atoms that are chemically bonded together.
  • Smallest particle into which matter can be divided.
  • The combining power (or capacity) of an element.
  • Both A and B.
According to Dalton, atoms of different elements combine with one another to form:
  • compounds
  • elements
  • solution
  • All of the above
When atoms of one element are combined with atoms of another element, the result is a(n) _________ of a compound.
  • electron
  • ion
  • molecule
  • enzyme
Cations carry  a  ___________ charge. 
  • positive
  • negative
  • no charge
  • none of these
Tungsten is a metal used in the filament of incandescent bulbs. What is the chemical symbol of Tungsten?
  • W
  • Tn
  • Tu
  • Wo
Which one of the following scientist's proposed the law of conservation of mass?
  • J.J. Thomson
  • John Dalton
  • Rutherford
  • Berzelius
Molecular mass of $$Ca(OH)_2$$ is :
  • $$61$$
  • $$57$$
  • $$74$$
  • None of above
State the atomic mass of $$H_2O$$?
  • $$16$$ u
  • $$17$$ u
  • $$18$$ u
  • $$15$$ u
Hydrogen atom has an approximate diameter of:
  • $$10^{-9}\ m$$
  • $$10^{-10}\ m$$
  • $$9^{-10}\ m$$
  • $$10^{-11}\ m$$
 A symbol of an element represents:
  • one atom of the element
  • one molecule of the element
  • all the atoms of the element
  • all the molecules of the element
Indicate whether the following statement is true or false.
Molecules can exist independently.
  • True
  • False
Indicate whether the following statement is true or false.
Molecules combine to form atoms.
  • True
  • False
$$10.0\ g$$ of $$CaCO_{3}$$ on heating gave $$4.4\ g$$ of $$CO_{2}$$ and $$5.6\ g$$ of $$CaO$$. This observation is in agreement with the:
  • law of constant composition
  • law of multiple proportion
  • law of reciprocal proportion
  • law of conservation of mass
The weight of gaseous mixture containing $$6.02 \times 10^{23}$$ molecules of nitrogen and $$3.01\times 10^{23}$$ molecules of sulphur dioxide is:
  • 46
  • 92
  • 60
  • 30
Number of atoms in $$558.5$$ gram Fe is:
[Atomic mass of $$Fe = 55.85\ u$$] 
  • twice that of 60 g carbon
  • $$6.023\times 10^{22}$$
  • half that in $$8$$g He
  • $$558.5\times6.023\times 10^{23}$$
Which of the following has highest mass?
  • $$50$$ g of iron
  • $$5$$ moles of nitrogen gas
  • $$5 \times 10^{23}$$ atoms of carbon
  • All are equal
$$10$$ grams each of  $$O_{2},\ N_{2}$$ and $$Cl_{2}$$ are kept in three bottles. The correct order of arrangement of bottles containing decreasing number of molecules is:
  • $$O_{2} >\ N_{2}>\ Cl_{2}$$
  • $$Cl_{2}>\ N_{2}>\ O_{2}$$
  • $$Cl_{2}>\ O_{2}>\ N_{2}$$
  • $$N_{2}>\ O_{2}>\ Cl_{2}$$
Irrespective of the source, a pure sample of water always yields $$88.89\%$$ oxygen by mass and $$11.11\%$$ hydrogen by mass. This is explained by the law of:
  • conservation of mass
  • constant proportion
  • multiple proportion
  • none of these
$$8$$ g of $$O_{2}$$ has the same number of molecules as:
  • 7 gms of $$CO$$
  • 14 gms of $$CO$$
  • 22 gms of $$CO_{2}$$
  • 44 gms of $$CO_{2}$$
Choose the correct option for the following statement.

The use of $$^{12}C$$ scale has superseded the older scale of atomic mass based on $$^{16}O$$ isotope, one important advantage of the former being: 
  • The atomic masses on $$^{12}C$$ scale became whole numbers.
  • $$^{12}C$$ is more abundant in the earths crust than $$^{16}O$$.
  • The difference between the physical and chemical atomic masses got narrowed down significantly.
  • $$^{12}C$$ is situated midway between metals and non-metals in the periodic table.
The number of molecules present in $$4.4$$ g of $$CO_{2}$$ gas is:
  • $$6.022\times 10^{23}$$
  • $$5.022\times 10^{23}$$
  • $$6.022\times 10^{24}$$
  • $$6.022\times 10^{22}$$
Which of the following is the best example to demonstrate the law of conservation of mass?
  • 12 gm of carbon combines with 32 gm of oxygen to form 44 gm of $$CO_{2}$$.
  • When 72 gm of carbon is heated in a vacuum and no change in its mass takes place.
  • The weight of a piece of platinum is the same before and after heating in air.
  • None of these
When equal masses of methane and sulphur dioxide are taken, then the ratio of their molecules is:
  • 1 : 1
  • 1 : 2
  • 2 : 1
  • 4 : 1
Which one of the following contains a same number of atoms as there are in 12 grams of magnesium?
  • 12 grams of carbon
  • 40 grams of calcium
  • 16 grams of oxygen
  • 7 grams of carbon monoxide
Which of the following gases contain the same number of molecules as that of $$16$$ g of oxygen?
  • $$16$$ g of $$O_{3}$$
  • $$32$$ g of $$SO_{2}$$
  • $$16$$ g of $$SO_{2}$$
  • None of these
$$4.6\times 10^{22}$$ atoms of an element weight $$13.8$$ g. What is the atomic mass of the element?
  • 290 u
  • 180.6 u
  • 34.4 u
  • 104 u
The ratio of the mass of a C-12 atom to that of an atom of element X (whose atomicity is four) is $$1: 9$$. The molecular mass of element X is :
  • $$480\ gmol^{-1}$$
  • $$432\ gmol^{-1}$$
  • $$36\ gmol^{-1}$$
  • $$84\ gmol^{-1}$$
The weight of one molecule of $$C_{60} H_{122}$$ is:
  • $$1.2\times 10^{-20}g$$
  • $$5.025\times 10^{23}g$$
  • $$1.4\times 10^{-21}g$$
  • $$6.023\times 10^{23}g$$
Which of these has the maximum number of molecules?
  • $$7$$ g $$N_{2}$$
  • $$2$$ g $$H_{2}$$
  • $$16$$ g $$NO_{2}$$
  • $$16$$ g $$O_{2}$$
Which of the following contains highest number of atoms?
  • 4 gm of oxygen
  • 4 gm of carbon dioxide
  • 4 gm of helium
  • 4 gm of methane
Different samples of water were found to contain hydrogen and oxygen in the ratio of 1 : 8 by mass. This proves the law of:
  • multiple proportion
  • constant proportion
  • reciprocal proportion
  • conservation of mass
The maximum number of molecules are present in:
  • $$36$$ g $$H_{2} O$$
  • $$28$$ g $$CO$$
  • $$46$$ g $$C_{2} H_{5} OH$$
  • $$54$$ g $$N_{2} O_{5}$$
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