CBSE Questions for Class 9 Chemistry Atoms And Molecules Quiz 6 - MCQExams.com

Which scientist proposed the concept of atomic mass?
  • Avogadro
  • Gay Lussac
  • Proust
  • Dalton
Sum of atomic masses of all atoms in a formula unit of an ionic compound is known as :
  • molecular mass
  • formula mass unit
  • atomic mass
  • none of the above
Formula unit mass is calculated in the same way as molecular mass. There is a difference between them. What is it?
  • It is used for compounds whose constituent particles are not ions
  • It is used for substances whose constituent particles are ions
  • It is only used for substances with mass less than 100
  • None of the above
Molecular mass is expressed in:
  • kg
  • g
  • u
  • mg
Calculate the molecular mass (u) of $$\displaystyle ZnO$$.
$$ [Zn = 65u, O = 16u]$$
  • $$80$$
  • $$69$$
  • $$82$$
  • $$81$$
Which of these would support the idea that mass is conserved in a reaction that produces gas as a product?
  • Heating the reactants to ensure the reaction occurs in a gaseous state.
  • Subtracting the mass of the gas from the mass of the solid and liquid products.
  • Mixing the reactants and measuring their total mass.
  • Trapping the gas and measuring its mass.
The reaction of Copper with Sulphur
Mass of $$Cu$$ before reaction:$$3.17\ g$$
Mass of $$S$$ before reaction:$$2.93\ g$$
Mass of $$CuS$$ formed:$$4.78\ g$$
Mass of unreacted $$S$$:    ? 

Copper $$(Cu)$$ and Sulphur $$(S)$$ were heated in a covered container. After the reaction was complete, the unreacted sulphur was removed. The table contains the results of the investigation. How much sulphur, in grams, failed to react with the copper?
  • $$1.2$$
  • $$1.25$$
  • $$1.3$$
  • $$1.32$$
Calculate the formula unit mass (u) of $$\displaystyle NaCl$$:
$$ [Na=23u, Cl=35.5u]$$
  • $$54.5 u$$
  • $$55.5 u$$
  • $$56.5 u$$
  • $$58.5 u$$
Calculate the molecular mass (u) of Phosphoric Acid ($$\displaystyle { H }_{ 3 }{ PO }_{ 4 }$$).
$$[H=1, P=31, O=16]$$
  • 96
  • 97
  • 98
  • 99
Calculate the formula unit mass (u) of $$\displaystyle { CaCl }_{ 2 }$$.
 [ Ca = 40 u, Cl = 35.5 u]
  • 111 u
  • 101 u
  • 91 u
  • 55 u
Calculate the molecular mass of Nitric acid ($$\displaystyle { HNO }_{ 3 }$$).
  • 60
  • 61
  • 62
  • 63
Calculate the molecular mass (u) of Sulphuric acid ($$\displaystyle { H }_{ 2 }{ SO }_{ 4 }$$).
  • 96
  • 97
  • 98
  • 49
When $$1.375\ g$$ of cupric oxide is reduced on heating in a current of hydrogen, the weight of copper remaining $$1.098\ g$$. In another experiment, $$1.179\ g$$ of copper is dissolved in nitric acid, and the resulting copper nitrate is converted into cupric oxide by ignition. The weight of cupric oxide formed is $$1.476 \ g$$. This is in agreement with :
  • Law of definite proportion
  • Law of mass conservation
  • Law of momentum conservation
  • None of the above
Mass number is denoted by:
  • D
  • S
  • A
  • Z
Which of the following is not a postulate of Dalton's atomic theory?
  • All matter is made of very tiny particles called atoms
  • Atoms of a given element are not identical in mass and chemical properties
  • Atoms combine in a ratio of small whole numbers to form compounds
  • The relative number and kinds of atoms are constant in a given compound
Who stated the law of constant proportion?
  • Archimedes
  • Dalton
  • Proust
  • Antony Lavoisier
When $$3\ g$$ of carbon is burnt in $$8\ g$$ of oxygen, $$11 g$$ of carbon dioxide is produced. What mass of carbon dioxide will be formed when $$3\ g$$ of carbon is burnt in $$50\ g$$ oxygen?
  • $$12\ g$$
  • $$13\ g$$
  • $$11\ g$$
  • $$10\ g$$
Which of the following symbol of elements is not taken from Latin names?
  • $$K$$
  • $$Na$$
  • $$Cu$$
  • $$Zn$$
In ammonia, nitrogen and hydrogen always combine in $$14:3$$ ratio by mass. This is in agreement with :
  • Law of conservation of mass
  • Law of definite proportion
  • Law of multiple proportion
  • Law of combining volume
Which is not the method used for creating the symbols of elements?
  • Some symbols of elements were taken from names of elements in Latin, Greek or German
  • Symbols of some elements were taken from names of places
  • Some symbols of elements were taken from specific colours
  • Symbols of some elements were taken from the letters of elements written in reverse order
Who laid the foundation of chemical sciences by experimentally establishing laws of chemical combination along with other scientists?
  • Proust
  • Antoine Lavoisier
  • Dalton
  • None of the above
Which of the following statement is true about mole?
  • It is used to calculate number of particles.
  • 1 mole is equal to $$6.023\times10^{23}$$ particles.
  • It is the chemist's counting unit
  • All of the above
The cation and anion present in $$HNO_3$$ are :
  • $$H^+, NO_3^-$$
  • $$H^-, NO_3^+$$
  • $$H^+, NO_3^+$$
  • $$H^-, NO_3^-$$
Which Indian philosopher was the first one to postulate the idea of matter divisibility around 500 B.C?
  • Democritus
  • Leucippus
  • Pakudha Katyayama
  • Maharishi Kanad
What is the old symbol for mercury?
  • None of the above
One gross : One mole : : 144 : ?
  • $$6.023\times10^{23}$$
  • $$6\times10^{20}$$
  • $$10^{23}$$
  • None of the above
What is the old symbol of copper?
The symbol of silver proposed by Dalton is
A positively charged ion is called :
  • molecule
  • atom
  • anion
  • cation
Avogadro number is the number of atoms present in exactly:
  • $$16\ g$$ of oxygen
  • $$12\ g$$ of carbon
  • $$2\ g$$ of hydrogen
  • None of the above
The anion in $$CaCl_2$$ is :
  • $$Ca^{2-}$$
  • $$Cl^-$$
  • $$Ca^{2+}$$
  • $$Cl^+$$
Which of the following configuration is most likely to form an anion?
  • $$2,\,6$$
  • $$2,\,8,\,1$$
  • $$2,\,1$$
  • $$2,\,2$$
Atom : .................... : : Electrons : Negatively charged
  • No charge
  • Positively charged
  • Negatively charged
  • None of the above
Who laid the foundation of chemical sciences by establishing two important laws of chemical combination?
  • Antonie Lavoisier
  • Avogadro
  • Proust
  • Democritus

An Indian philosopher who said that the smallest particles normally exist in a combined form which gives us various forms of matter is:
  • Pakudha Katyayama
  • Lavoisier
  • Maharishi Kanad
  • None of the above
Which of the following configuration will form a cation?
  • $$2,\,8,\,7$$
  • $$2,\,7$$
  • $$2,\,8,\,8$$
  • $$2,\,8,\,2$$
Why is atom electrically neutral ?
  • It has same number of neutrons & protons
  • It has same number of neutrons & electrons
  • It has same number of protons & electrons
  • None of the above
_________ deduced that all kind of matter are made up of "anu".
  • Dalton
  • Sir. J. J. Thomson
  • Kanad
  • Rutherford
1 Nanometer is equal to :
  • $$10^{-10} m$$
  • $$10^{-9} m$$
  • $$10^{-8} m$$
  • $$10^{-7} m$$
Which of the following atomic number will most likely form an anion?
  • $$13$$
  • $$18$$
  • $$12$$
  • $$17$$

Which law was given by Antoine L. Lavoisier?
  • Laws of multiple proportion
  • Law of conservation of mass
  • Both A and B
  • None of the above

State whether the statement is true or false:

When we rub a comb through the hair, or a glass rod with silk, the comb, and the glass rod becomes charged. It shows that "Atoms are Indivisible".
  • True
  • False
The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. This illustrates the law of:
  • Constant proportion
  • Conservation of mass
  • Multiple proportion
  • Reciprocal proportion

In the formation of iron sulphide, by heating iron and sulphur, the mass of iron(II) sulphide __________ when compared with a total mass of iron and sulphur.
  • increases
  • decreases
  • remains same
  • None of the above
Law of definite proportion does not apply to nitrogen oxide because:
  • Atomic weight of nitrogen is not conserved
  • Molecular weight of nitrogen is variable
  • Nitrogen forms multiple compounds with oxygen
  • Atomic weight of oxygen is variable

According to Dalton, atom combines in a _________ ratio to form compounds.
  • variable
  • fixed
  • Both A and B
  • None of the above

The law of conservation of mass will not be strictly valid unless mass and energy are considered together.
  • True
  • False

A 78.0 g sample of an unknown compound contains 12.4 g of hydrogen.  What is the percent by mass of hydrogen in the compound?
  • 25%
  • 35%
  • 16%
  • 50%

The law of conservation of mass is in agreement with Dalton's atomic theory.
  • True
  • False

Law of conservation of mass is also known as :
  • Law of indestructibility
  • Law of mass action
  • Law of conservation of energy
  • None of the above
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