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Questions For atoms and molecules class 9 mcq
In a compound such as water, the ratio of the mass of hydrogen to the mass of oxygen is always ............, whatever the source of water.
(A) 2:3
(B) 1:8
(C) 3:8
(D) None Of The above
In ammonia, nitrogen and hydrogen are always present in the which it is obtained.
(A) 10:3
(B) 13:3
(C) 14:3
(D) None Of The above
In a chemical substance the elements are ................ present in definite proportions by mass.
(A) Never
(B) Always
(C) Sometimes
(D) None Of The above
Law of constant proportions which is also known as the law of definite proportions.
(A) True
(B) False
(C) Not Say
(D) Not Possible
Who said that the smallest particles of matter are atoms.
(A) Rutherford
(B) Dalton
(C) Thomson
(D) None Of The above
According to Dalton's atomic theory, all matter, whether an element, a compound or a mixture is composed of small particles called .........
(A) Atoms
(B) Electrons
(C) Molecules
(D) Nucleus
Atomic radius is measured in .........
(A) Centimetre
(B) Millimetre
(C) Nanometer
(D) None Of The above
IUPAC stands for International Union of Pure and Applied Chemistry.
(A) True
(B) False
(C) Not Say
(D) Not Possible
Law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction.
(A) True
(B) False
(C) Not Say
(D) Not Possible
3 g of carbon combines with 4 g of oxygen to form ......
(A) CO2
(B) CO
(C) CO3
(D) None Of The above
While searching for various atomic mass units, scientists initially took 1/16 of the mass of an atom of naturally occurring oxygen as the unit. This was considered relevant due to......
(A) oxygen reacted with a large number of elements and formed compounds.
(B) this atomic mass unit gave masses of most of the elements as whole numbers.
(C) Both a and b
(D) None Of The above
One atomic mass unit is a mass unit equal to exactly one - twelfth (1/12th) the mass of one atom of ...........
(A) C-12
(B) 0-16
(C) H-1
(D) None Of The above
The relative atomic masses of all elements have been found with respect to an atom of ..............
(A) C-12
(B) 0-16
(C) H-1
(D) None Of The above
Which of the following statement is correct.
(A) Atoms of most elements are not able to exist independently.
(B) Atoms form molecules and ions.
(C) These molecules or ions aggregate in large numbers to form the matter that we can see, feel or touch.
(D) All of the correct
The relative atomic mass of the atom of an element is defined as the average mass of the atom, as compared to 1/12 the mass of one carbon-12 atom.
(A) True
(B) False
(C) Not Say
(D) Not Possible
A molecule is in general a group of two or more ........... that are chemically bonded together that is tightly held together by attractive forces.
(A) lon
(B) Molecule
(C) Substance
(D) none of the above
The number of ............ constituting a molecule is known as its atomicity.
(A) lons
(B) Charge
(C) Atoms
(D) None Of The above
The ratio by number of atoms for water is H:0
(A) 2:3
(B) 1:2
(C) 2:1
(D) None Of The above
Identify the incorrect statement.
(A) Compounds composed of metals and non-metals contain charged species.
(B) The charged species are known as ions.
(C) An ion is a charged particle and can be negatively or positively charged.
(D) None of These
Sodium chloride (NaCl) has positively charged sodium ions(Na) and negatively charged chloride ions (CI).
(A) True
(B) False
(C) Not Say
(D) Not Possible
A group of atoms carrying a charge is known as a polyatomic ion.
(A) True
(B) False
(C) Not Say
(D) Not Possible
The combining power (or capacity) of an element is known as its.......
(A) Valence electrons
(B) Valency
(C) Atomic Number
(D) None Of The above
Valency can be used to find out how the atoms of an element will combine with the atom(s) of another element to form a chemical compound.
(A) True
(B) False
(C) Not Say
(D) Not Possible
Identify the incorrect match
(A) Calcium oxide-----(Cao)
(B) Sodium chloride----(NaCl)
(C) Iron sulphide-----(FeSO)
(D) Copper oxide------(Cuo)
Identify the incorrect match.
(A) Oxygen, chlorine, sulphur are non-metals and are written on the right.
(B) Calcium, sodium, iron and copper are metals, and are written on the left.
(C) None of the above
(D) All are correct
The molecular mass of a substance is the sum of the atomic masses of all the atoms in a molecule of the substance.
(A) True
(B) False
(C) Not Say
(D) Not Possible
Calculate the relative molecular mass of water (H20).
(A) 14u
(B) 16u
(C) 18u
(D) None Of The above
Calculate the molecular mass of HNO3
(A) 60u
(B) 63u
(C) 65u
(D) 61u
The formula unit mass of a substance is a sum of the atomic masses of all atoms in a formula unit of a compound.
(A) True
(B) False
(C) Not Say
(D) Not Possible
Choose The Correct formula of
(A) sodium oxide---(Na2O)
(B) aluminium chloride---(AgCl2)
(C) sodium sulfide ---(Na2S)
(D) magnesium hydroxide---(Mg(OH)2)
Calculate the formula unit mass of CaCl2.
(A) 109u
(B) 110u
(C) 111u
(D) None Of The above
Mole of any substance is fixed, with a value of 6.022 x 10^23
(A) 1 mole
(B) 2 mole
(C) 3 mole
(D) None Of The above
Mass of 1 mole of a substance is equal to its relative atomic or molecular mass in grams.
(A) True
(B) False
(C) Not Say
(D) Not Possible
The Chemical Symbol For nitrogen gas is.
(A) N
(B) N+
(C) N2
(D) Ng
The Chemical Symbol For Hygrogen gas is.
(A) H+
(B) H-
(C) Hg
(D) H2
The Chemical Symbol For Sodium is.
(A) Na
(B) Sd
(C) NA
(D) NH
Who gave the law of chemical combination?
(A) John Dalton
(B) Lavoisier
(C) Proust
(D) Democritus
The indivisibility of atom was proposed by.
(A) Einstein
(B) Bohr.
(C) Rutherford
(D) Bohrein
The correct symbol for silver is.
(A) Ag
(B) S
(C) Ar
(D) Al
The ratio of Hydrogen and Oxygen in water is.
(A) 1:8
(B) 8:1
(C) 2:1
(D) 1:2
The accepted unit of atomic mass and molecular mass is
(A) amu
(B) g
(C) kg
(D) km
The modern atomic symbols were proposed by
(A) Dalton
(B) Lavoisier
(C) Berzelius
(D) None of these
Symbol of Iron is
(A) Ir
(B) I
(C) Fe
(D) None of these
Molecular mass of water (H2O) is
(A) 18g
(B) 8g
(C) 33g
(D) 34g
One mole of a compound contains
(A) 6.023 x 1023 atoms
(B) 6.023 x 1024 atoms
(C) 60.23 x 10% atoms
(D) 6.023 x 1025 atoms
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