CBSE Questions for Class 9 Chemistry Atoms And Molecules Quiz 11 - MCQExams.com

Iron forms two oxides, in first oxide $$56$$ grams of Iron is found to be combined with $$16$$ gram oxygen and in second oxide $$112$$ gram of Iron is found to be combined with $$48$$ gram oxygen. This data satisfy the law of
  • Conservation of mass
  • Reciprocal proportion
  • Multiple proportions
  • Combining volume
Specific volume of cylindrical virus particle is $$6.02 \times {10^{ - 2}}\,\,cc/gm$$ whose radius and length are 7 A and 10 A respectively. If $${N_A} = 6.02 \times {10^{23}}.$$ Find molecular weight of virus.
  • $$15.4\,\,kg/mol$$
  • $$1.54 \times {10^4}\,\,kg/mol$$
  • $$3.08 \times {10^4}\,\,kg/mol$$
  • $$3.08 \times {10^3}\,kg/mol$$
The number of electrons in $$3.1\ mg\ NO_{3}^{-}$$ is ______.
$$(Given: N_{A}=6\times 10^{23})$$
  • $$1.6\times 10^{-3}$$
  • $$9.6 \times 10^{20}$$
  • $$32$$
  • $$9.6 \times 10^{23}$$
Arrange the following in order of decreasing masses:
  • $$10 ^ { 23 }$$ molecules of $$\mathrm { CO } _ { 2 }$$ gas
  • 0.1 g atom of silver
  • I gram of carbon
  • 0.1 mole of $$\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$$
  • $$10 ^ { 23 }$$ atoms of calcium.
The number of moles in $$ 1.6 \times 10^4 $$ grams of $$ Ca(OH)_2 $$ are
  • 2.162
  • 21.62
  • 0.2162
  • 216.2
The weight of sulphuric acid needed for dissolving $$3 \mathrm { gm }$$ magnesium carbonate is:
  • $$3.5 \mathrm { gm }$$
  • $$7.0 \mathrm { gm }$$
  • $$1.7 \mathrm { gm }$$
  • $$17.0 \mathrm { gm }$$
The present atomic weight scale is based on:
  • $$^{12}{ C }$$
  • $$^{16}{ O }$$
  • $$^{1}{ H }$$
  • $$^{13}{ C }$$
The relative formula mass $$(M_{r})$$ of calcium carbonate $$(CaCO_{3})$$ is $$100$$. What is the mass of carbon present in $$100\ g$$ of calcium carbonate?
  • $$12\ g$$
  • $$36\ g$$
  • $$40\ g$$
  • $$60\ g$$
A compound contains $$7$$ carbon atoms, $$2$$ oxygen atoms and $$9.96\times 10^{-24}\,g$$ of other elements. The molecular mass of compound is $$(N_A =6\times 10^{23})$$
  • $$122$$
  • $$116$$
  • $$148$$
  • $$154$$
The volume of one mole of water at $$277\ K$$ is $$18\ ml$$. One $$ml$$ of water contains $$20$$ drops. The number of molecules in one drop of water will be $$(N_{A}=6\times 10^{23})$$
  • $$1.07\times 10^{21}$$
  • $$1.67\times 10^{21}$$
  • $$2.67\times 10^{21}$$
  • $$1.67\times 10^{20}$$
For $$CuSO_4.5H_2O,$$ which is the correct mole relationship?
  • mole of $$Cu= 9 \times mole\ of\ O$$
  • mole of $$Cu= 4 \times mole\ of\ O$$
  • mole of $$Cu= 5 \times mole\ of\ O$$
  • mole of $$O= 9 \times mole\ of\ Cu$$
Molecular mass of dry air is ________________.
  • less than moist air
  • greater than moist air
  • equal to moist air
  • may be greater or less than moist air
Cortisone is a molecular substance containing $$21$$ atoms of carbon per molecule. The mass percentage of carbon in cortisone is $$69.98$$%. What is the molecular mass of cortisone?      
  • $$180.05$$
  • $$360.1$$
  • $$312.8$$
  • $$205.8$$
Equivalent mass of a bivalent metal is $$32.7$$ Molecular mass of its chloride is _____________.
  • $$68.2$$
  • $$103.7$$
  • $$136.4$$
  • $$4166.3$$
What is the definition of relative atomic mass, $$A_{r}$$?
  • $$\left (\dfrac {\text {average mass of naturally occurring atoms of an element}}{\text {mass of one atom of}^{12}C}\right )\times 12$$
  • $$\left (\dfrac {\text {average mass of naturally occurring atoms of an element}}{\text {mass of one atom of}^{12}C \times 12}\right )$$
  • $$\left (\dfrac {\text {average mass of naturally occurring atoms of an element}}{\text {mass of one atom of}^{12}C}\right )$$
  • $$\left (\dfrac {\text {mass of one atom of}^{12}C}{\text {average mass of naturally occurring atoms of an element}}\right )$$
The molecular mass of a compound containing only one nitrogen atom can be
  • $$73$$
  • $$74$$
  • $$146$$
  • $$148$$
The minimum mass of water needed to slake $$1\ kg$$ of quicklime, assuming no loss by evaporation, is:
  • $$243.2\ g$$
  • $$642.8\ g$$
  • $$160.7\ g$$
  • $$321.4\ g$$
A sample of ozone gas is found to be $$40\%$$ dissociated into oxygen. The average mass of sample should be
  • $$41.60$$
  • $$40$$
  • $$42.35$$
  • $$38.40$$
The number of hydrogen atoms in $$0.9\ g$$ glucose $$C_{6}H_{12}O_{6}$$, is same as
  • $$0.48\ g$$ hydrazine, $$N_{2}H_{4}$$`
  • $$0.17\ g$$ ammonia, $$NH_{3}$$
  • $$0.30\ g$$ ethane, $$C_{2}H_{6} $$
  • $$0.03\ g$$ hydrogen $$H_{2}$$
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 proportions
  • Conservation of mass
  • Multiple proportions
  • Reciprocal proportions
Which phrase would be incorrect to use:
  • A molecule of a compound
  • An atom of an element
  • An atom of a molecule
  • None of these
Which of the following statement (s) is/are correct about the Avogadro's number ?
  • It is the number of atoms contained in one mole of any element.
  • It is the number of electrons required to deposit one mole of atoms of any metallic element from a solution of its salt.
  • It is the number of grams of any element that contains its $$6.022\times 10^{23}$$ atoms.
  • It is the number of particles (atoms, molecules or ions) required to make one gram of the substance under consideration
Pressure of $$1$$g of an ideal gas A at $$27^o$$C is found to be $$2$$ bar. When $$2$$ g of another ideal gas B is introduced in the same flask at same temperature the pressure becomes $$3$$ bar. What is the relationship between their molecular masses?
  • $$2M_B=M_A$$
  • $$M_B=M_A$$
  • $$M_B=4M_A$$
  • $$M_B=2M_A$$
Avogadro number is
  • Number of atoms in one gram of element
  • Number of millilitres which one mole of a gaseous substances occupies at $$NTP$$
  • Number of molecules present in one gram molecular mass of a substance
  • All of these
The composition of universe is approximately $$90\%$$ hydrogen and $$10\%$$ helium, by mass. It represented that 
  • there are $$18$$ hydrogen atoms in the universe per atom of helium.
  • there are $$9$$ hydrogen atoms in the universe per atom of helium.
  • there are $$36$$ hydrogen atoms in the universe per atom of helium
  • the average molar of universe is $$2.20\ g$$ per mole
If the atomic weight of carbon were set at 24 amu, the value of the Avogadro constant would be:
  • $$ 6.022 \times 10^{23} $$
  • $$ 12.044 \times 10^{23} $$
  • $$ 3.011 \times 10^{23} $$
  • None of these
1 amu is equal to
  • $$\dfrac{1}{12}$$ of C-12
  • $$\dfrac{1}{14}$$ of O-16
  • $$1\,g$$ of hydrogen
  • $$1.66 \times 10^{-23} kg$$
The modern atomic weight scale is based on
  • $$C^{12}$$
  • $$O^{16}$$
  • $$H^1$$
  • $$C^{13}$$
In water, the proportion of oxygen and hydrogen by mass is: 
  • $$ 1: 4 $$
  • $$ 1 : 8 $$
  • $$ 4 : 1 $$
  • $$ 8 : 1 $$
Which of the following postulates of Dalton's atomic theory is challenged by the next generation's scientists?
  • All matter is made of very tiny particles called atoms,
  • Atoms are particles, which cannot be created or destroyed in a chemical reaction.
  • Atoms of a given elements are identical in mass, shape and chemical properties
  • None of the above
A molecule can be defined as the:
  • A group of two or more atoms that are chemically bonded together
  • The smallest particle of an element or a compound that is capable of independent existence and shows all the properties of that substance
  • The substance which is formed by the combination of atoms of the same element or of different elements
  • All these are correct.
Write true or false for the following statements:
A compound is a substance composed of two or more elements, chemically combined in a fixed proportion.
  • True
  • False
Which of the following is not an element?
  • Oxygen gas
  • Carbon dioxide gas
  • Sulphur dioxide gas
  • Nitrogen dioxide gas
  • All of the above
Which of the following represents  amu?
  • Mass of 1 hydrogen atom
  • Mass of C-12 atom
  • mass of O-16 atom
  • 1/12th of mass of C-12 atom
Write true or false for the following statement:
One atomic mass unit is a mass unit equal to exactly one-twelfth (1/12th) the mass of one atom of carbon-12.
  • True
  • False
In water, the ratio of the mass of hydrogen to the mass of oxygen is always $$1 : 8$$, whatever is the source of water.
  • True
  • False
One of the statements of Dalton's atomic theory is given below:
Compounds are formed when atoms of different elements combine in a fixed ratio.
Which of the following laws is/are not related to this statement?
  • Law of conservation of mass
  • Law of definite proportions
  • Law of multiple proportions
  • Avogadro law
Which of the following reactions is not according to the law of conservation of mass?
  • $$2Mg(s)+O_2(g)\to 2MgO(s)$$
  • $$C_3H_3(g)+O_2(g)\to CO_2(g)+H_2O(g)$$
  • $$P_4(s)+5O_2(g)\to P_4O_{10}(s)$$
  • $$CH_4(g)+2O_2(g)\to CO_2(g)+2H_2O(g)$$
Mass is measure of the amount of matter.
  • True
  • False
Fill in the blanks:-

The formula unit mass of $$Ca_3(PO_4)_2$$ is_______.
  • 310
  • 270
  • 330
  • 410
The smallest part of an element capable of independent existence is called an atom.
  • True
  • False
The smallest part of the matter, capable of independent existence is called an atom.
  • True
  • False
The central part of the atom is called the nucleus.
  • True
  • False
The outermost shell of an atom is known as
  • valency
  • valence electrons
  • nucleus
  • valence shell
Write 'true' or 'false' for the following statement:
An atom on the whole has a positive charge.
  • True
  • False
Choose the correct answer from the options given below.
In water, the hydrogen-to-oxygen mass ratio is:
  • $$1 : 8$$
  • $$1 : 16$$
  • $$1 : 32$$
  • $$1 : 64$$
Which of the following substance is made up of only one type of particle?
  • compound
  • element
  • mixture
  • mixed metal
Sugar, salt, water, ammonia are:
  • elements
  • compounds
  • mixtures
  • All of the above
According to Daltons atomic theory atoms are indestructible.
  • True
  • False
Which one of the following is the standard for atomic mass?
  • $$ { }_{1}^{1} \mathrm{H} $$
  • $$ { }_{6}^{12} \mathrm{C} $$
  • $$ { }_{6}^{14} \mathrm{C} $$
  • $$ { }_{8}^{16} \mathrm{O} $$
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