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CBSE Questions for Class 9 Chemistry Atoms And Molecules Quiz 4 - MCQExams.com

A neutral atom of an element has a nucleus with a nuclear charge 13 times and mass 27 times that of hydrogen nucleus. What is the ratio of electrons to protons in its stable positively charged ion?
  • 27 : 13
  • 10 : 19
  • 10 : 13
  • 10 : 14
When hydrogen burns in oxygen, _________ is produced.
  • water
  • hydrogen peroxide
  • both A and B
  • none of these
The percentage by mole of NO2 in a mixture of NO2(g) and NO(g) having average molecular mass 34 is :
  • 25%
  • 20%
  • 40%
  • 75%
The symbol for SI unit of mole is:
  • mol
  • mole
  • M
  • m
N2O is heavier than O2.
  • True
  • False
Various theories were put forward to study  the nature of atom. The main postulates of Dalton's atomic theory are:
  • Dalton's atomic theory proposed that all matter was composed of atoms.
  • Dalton's atomic theory proposed that all matter was composed of molecules.
  • All atoms of an element are identical.
  • The atoms of different elements vary in size and mass.
According to Dalton's atomic theory, the smallest particle from which matter is made up of is called as:
  • atom
  • ion
  • electron
  • molecule
1 amu is equal to 1.66×1024 g.
  • True
  • False
The number of moles of 'X ' atoms in 93 gm of 'X' are:
(Molecular Weight of X=31 g/mole)
  • 3
  • 3.5
  • 4
  • 2
The number of atoms in 60 g of neon[Ne] are:
(Molar mass of Ne=20 g/mole)
  • 6×6.022×1023 atoms
  • 2×6.022×1023 atoms
  • 5×6.022×1023 atoms
  • 3×6.022×1023 atoms
What mass of Na will contain 6.023×1023 number of atoms?
  • 23 g
  • 46 g
  • 6.023 g
  • 11.5 g
Atomic number (Z) of a neutral atom and mass number (A) of an atom are equal to: 
(Here n = number of neutrons and p = number of protons):
  • Z = n and A = n+p
  • Z = e and A = n+e
  • Z = p and A = n+p
  • Z = n and A = p+e
The number of potassium atoms present in 117 g of potassium sample (Molecular Weight =39 g/mole) is:
  • 9×6.023×1023 atoms
  • 7×6.023×1023 atoms
  • 4×6.023×1023 atoms
  • 3×6.023×1023 atoms
A/An______ is the smallest particle of a substance which can take part in a chemical reaction.
  • atom
  • molecule
  • both A and B
  • none of the above
The mass of one molecule of compound C60H122 is :
  • 1.3×1020g
  • 5.01×1021g
  • 3.72×1023g
  • 1.4×1021g
The number of nitrogen atoms in 21 g of nitrogen are:
(Molecular Weight of Nitrogen =14 g/mole)
  • 0.75NA
  • 1.5NA
  • 21NA
  • 14NA
Which of the following is a suitable example for illustrating the law of conservation of mass? (Atomic mass of O = 16 u; H = 1 u)
  • 18g of water is formed by the combination of 16g oxygen with 2g of hydrogen.
  • 18g of water in liquid state is obtained by heating 18g of ice.
  • 18g of water is completely converted into vapour state on heating.
  • 18g of water freezes at 4oC to give same mass of ice.
The molecular mass of CuSO4.5H2O is:
(Atomic mass of Cu = 63.5, H = 1, O = 16, S = 32)
  • 233.5 gm/mole
  • 249.5 gm/mole
  • 251.5 gm/mole
  • 247.5 gm/mole
Which has a higher mass : 1 mole of CO2 or 1 mole of CO? (Mass of C=12,  Mass of O=16)
  • CO2
  • CO
  • Both CO2 and CO have same mass
  • None of the above
Two elements always combine together in a fixed ratio by weight.
  • True
  • False
Consider the following statements:
(a) Molecular mass of CH3OH is 32 u.
(b) In NH3, the ratio of N and H by mass is 14:3.
(c) The formula mass of CaCl2 is 111 u.
(d) Isotopes have same mass number.

Which of the above statements are correct?
  • (a) and (c)
  • (a), (b) and (d)
  • (a), (b) and (c)
  • (a), (c) and (d)
The molecular mass of (NH4)2CO3 is:
Given atomic mass of H = 1, O = 16, C = 12, N = 14.
  • 96 gm/mole
  • 98 gm/mole
  • 94 gm/mole
  • 80 gm/mole
Sodium chloride (NaCl) reacts with silver nitrate (AgNO3) to produce silver chloride (AgCl) and sodium nitrate (NaNO3). The law which satisfies this equation is ___________________ .
  • conservation of mass
  • conservation of energy
  • newton's law
  • dalton's law
Two chemical species X and Y combine together to form a product P which contains both X and Y

                                                     X+YP

X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species X,Y and P are correct?

(i)    P is a compound
(ii)   X and Y are compounds
(iii)  X and Y are elements
(iv)  P has a fixed composition
  • (i), (ii) and (iii)
  • (i), (ii) and (iv)
  • (ii), (iii) and (iv)
  • (i), (iii) and (iv)
State whether the given statement is true or false.

An atom is electrically neutral though it contains charged particles.
  • True
  • False
1.2×1024 atoms of iron weighs  ______ grams.
  • 90
  • 111.5
  • 80
  • 70
An element A (atomic weight =12) and B (atomic weight =35.5) combines to form a compound X. If 4 mol of B combines with 1 mol of A to give 1 mol of X. The weight of 1 mol of X would be :
  • 47.5 g
  • 74.0 g
  • 154.0 g
  • 148.8 g
The number of electrons and protons are always equal in all atoms.
  • True
  • False
Which of the following options contains only elements?
  • Air, water, oxygen
  • Hydrogen, oxygen, brass
  • Air, water, iron
  • Calcium, sulphur, carbon
State True or False.

There is no difference between one mole and one gram molecule.
  • True
  • False
State True or False.
Mass of reactants is always equal to the mass of the products. (Don't consider nuclear reaction)
  • True
  • False
Law of conservation of mass was put forward by :
  • Lavoisier
  • Dalton
  • Priestly
  • Thomson
A compound was found to contain 5.37 % of Nitrogen. What is the minimum molecular weight of the compound?
  • 26.07 g
  • 2.607
  • 260.7
  • None
Atomic mass of an element is:
  • actual mass of one atom of the element
  • average mass of an atom of different atoms of the element
  • always a whole number
  • None of these
All samples of carbon dioxide contain carbon and oxygen in the mass ratio of 3:8. This is in agreement with the law of :
  • conservation of mass
  • constant proportion
  • multiple proportions
  • gaseous volumes
An organic compound contains 4% sulphur. Its minimum molecular weight is :
  • 200
  • 400
  • 800
  • 1600
Which of the following is not a compound?
  • Oxygen
  • Water
  • Sugar
  • Common salt
The smallest particle of a substance (element or compound) which has the properties of that substance and can exist independently is called a ..............
  • Molecule
  • Atom
  • Nucleus
  • Neutrons
.............. is the smallest unit of an element that maintains the properties of that element.
  • electron
  • atom
  • proton
  • ions
Calculate the molecular mass of H2O (Water)
  • 18
  • 36
  • 20
  • 16
An atom which is deficient of electrons is called a  ________ .
  • positive ion
  • proton
  • negative ion
  • none of these
Molecules are the components of:
  • Solutions
  • Gases
  • Solids
  • All of the above
State True or False.
The smallest particle of an element is molecule.
  • True
  • False
When hydrogen and oxygen combine to form water, they form:
  • an unstable compound
  • a stable mixture
  • an unstable mixture
  • an extremely stable compound
3 g of a hydrocarbon on combustion in excess of oxygen produces 8.8 g of CO2 and 5.4 g of H2O

The data illustrates the law of :
  • Conservation of mass
  • Multiple proportions
  • Constant proportions
  • None of the above
The weights of two elements which combines with one another are in the ratio of their:
  • atomic weight
  • molecular weight
  • equivalent weight
  • none of the above
Weight of oxygen in 32.2 g Na2SO4.10H2O is:
  • 20.8 gm
  • 22.4 gm
  • 2.24 gm
  • 2.08 gm
Modern atomic mass scale is based on the mass of:
  • H1
  • C12
  • C14
  • C16
Weight of oxygen in Fe2O3 and FeO is in the ratio of :
  • 3:2
  • 1:2
  • 2:1
  • 3:1
The percentage of copper and oxygen in a sample of CuO obtained from different methods were found to be same. This proves the law of :
  • Constant proportion
  • Multiple proportion
  • Reciprocal proportion
  • None of these
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