CBSE Questions for Class 9 Chemistry Atoms And Molecules Quiz 5 - MCQExams.com

An ionic compound of element $$M$$ and chlorine has the formula $$MCl_3$$, the molecular mass of $$MCl_3$$ is 118.5 u. What is the molecular mass of the oxide of an element $$M$$?
  • 28
  • 44
  • 72
  • 99
The difference between ions and atoms is of :
  • relative size
  • electronic configuration
  • presence of charge
  • All of the above
14 g of element X combine with 16 g of oxygen. On the basis of this information, which of the following is a correct statement?
  • The element X could have an atomic weight of 7 and its oxide is XO.
  • The element X could have an atomic weight of 14 and its oxide is $$X_2O$$.
  • The element X could have an atomic weight of 7 and its oxide is $$X_2O$$
  • The element X could have an atomic weight of 16 and its oxide is $$X_2O$$
Smallest particle of an element or a compound which is capable of independent existence is called:
  • atom
  • molecule
  • element
  • compound
A chemical equation is balanced in accordance with the law of
  • conservation of mass
  • multiple proportion
  • constant proportion
  • reciprocal proportion
Which law stated that 'matter is neither created nor destroyed'?
  • Law of multiple proportion
  • Law of conservation of energy
  • Law of constant composition
  • Law of conservation of mass
Which of these is not a molecule?
  • $$H_2$$
  • $$Cl$$
  • $$O_3$$
  • $$NaCl$$
The law of conservation of mass was given by :
  • Dalton
  • Proust
  • Lavoisier
  • Berzelius
One mole of any substance contains $$6.023\times10^{23}$$ particles. It was determined by
  • Berzilius
  • Avogadro
  • Dalton
  • Perin
Which atom contains exactly 15 neutrons?
  • $$P^{32}$$ (atomic number $$= 17$$)
  • $$S^{32}$$ (atomic number $$= 16$$)
  • $$O^{15}$$ (atomic number $$= 8$$)
  • $$N^{15}$$ (atomic number $$= 7$$)
Amongst the following, which has the highest molecular mass?
  • $$Cl_2$$
  • $$N_2$$
  • $$CH_3OH$$
  • $$NH_3$$
In a chemical reaction, when 14 g of sodium carbonate reacted with 10g of acetic acid (ethanoic acid), then it was observed that, 16.67 g of sodium acetate solution in water and 7.33 g of carbon dioxide were produced. Which law does this depicts?
  • Law of definite proportions
  • Law of conservation of mass
  • Law of constant proportions
  • Avogadro's law
Which of the following elements has the same molecular mass as its atomic mass?
  • Nitrogen
  • Neon
  • Oxygen
  • Chlorine
The value of Avogadro number is
  • $$6.25 \times {10}^{18}$$
  • $$6.022 \times {10}^{23}$$
  • $$96500$$
  • $$3.12 \times {10}^{18}$$
Any sample of pure water, irrespective of its source, contains 88.89% oxygen and 11.11 % hydrogen by mass. The data supports the:
  • Law of conservation of mass
  • Law of constant composition
  • Law of multiple proportion
  • Law of reciprocal proportion
720 g of water contains ______ moles of water.
  • 20
  • 40
  • 60
  • 80
Smallest possible unit of a compound which has independent existence is :
  • molecule
  • atom
  • ion
  • electron
The mass of $$Na$$ present in 11.7 g of $$NaCl$$ is:
  • 2.3 g
  • 4.6 g
  • 6.9 g
  • 7.1 g
Since Avogadro number is $$6.023\times {10}^{23}$$ and atomic mass of nitrogen is $$14$$ amu, one mole of $$N_2$$ gas will have:
  • $$0.5\times 6.023\times {10}^{23}$$ atoms
  • $$2\times 6.023\times {10}^{23}$$ atoms
  • $$14\times 6.023\times {10}^{23}$$ atoms
  • $$28\times 6.023\times {10}^{23}$$ atoms
Radius of atom is of the order :
  • $$10^{-10}-10^{-8}cm$$
  • $$10^{-12}-10^{-14}cm$$
  • $$10^{-14}-10^{-16}cm$$
  • $$10^{-16}-10^{-20}cm$$
One atomic mass unit is equivalent to
  • $$1.67\times 10^{-27} g$$
  • $$1.66\times 10^{-27} kg$$
  • $$1.67\times 10^{-27} mg$$
  • $$1.6\times 10^{-24} g$$
2.40 g of the element $$Z$$ combines exactly with 1.6 g of oxygen to form a compound with the formula $$ZO_2$$. What is the relative atomic mass of $$Z$$?
  • 24.0
  • 32.0
  • 48.0
  • 64.0
The mass of one atom of carbon-12 is:
  • $$1\ g$$
  • $$12\ g$$
  • $$12\times 6.02\times 10^{23}\ g$$
  • $$\dfrac {12}{6.02\times 10^{23}}\ g$$
An atom is:
  • The smallest particle of matter known
  • The smallest particle of a gas
  • The smallest indivisible particle of an element that can take part in a chemical change
  • Radioactive emission
Atomic theory was given by:
  • John Dalton
  • Neils Bohr
  • E. Rutherford
  • Haber Bosch
'All matter is composed of very small particles called Parmanu' was first suggested by:
  • John Dalton
  • J.J. Thomson
  • Kanad
  • William J. Crooke
Which of the following contains the largest number of molecules?
  • 0.2 mole of H$$_2$$
  • 8.0 mole of H$$_2$$
  • 17 g of H$$_2$$O
  • 6.0 g of CO$$_2$$
Which of the following weighs the most?
  • $$10^{23}$$ molecules of $$H_2$$
  • 1 mole of $$H_2$$O
  • 1 mole of $$N_2$$
  • $$10^{22}$$ molecules of $$O_2$$
6.4 g of oxygen will contain ______ number of oxygen molecules.
  • $$6.023 \times 10^{23}$$
  • $$6.023 \times 10^{22}$$
  • $$1.2046 \times 10^{23}$$
  • $$1.2046 \times 10^{22}$$
Which of the following statement is wrong?
  • An atom is electrically neutral.
  • The size of a cation is smaller than that of the corresponding atom.
  • The size of an anion is bigger than that of the corresponding atom.
  • An atom and its ion have an unequal number of protons.
Which of the following compound has formula mass of 322 u?
$$(H= 1, C=12, 0=16, Na=23, S=32, Cu=63.5)$$
  • $$Na_2CO_3.10H_2O$$
  • $$CuSO_4.5H_2O$$
  • $$Na_2CO_3.9 H_2O$$
  • $$Na_2SO_4.10 H_2O$$
Hydrogen combines with nitrogen in a 3:14 weight ratio to form ammonia. If every molecule of ammonia contains three atoms of hydrogen and one atom of nitrogen, an atom of nitrogen must weigh :
  • 14 times the mass of a hydrogen atom
  • 14/3 times the mass of a hydrogen atom
  • 3 times the mass of a hydrogen atom
  • 3/14 times the mass of a hydrogen atom
The sum of masses of the atoms in the molecules is known as :
  • Atomic mass
  • Molecular mass
  • Gram molecular weight
  • None of the above
The weight of one molecule of a compound of molecular formula $$C_{60} H_{122}$$ is:
  • $$1.2\times 10^{-20} g$$
  • $$5.025\times 10^{-23} g$$
  • $$1.4\times 10^{-21} g$$
  • $$6.023\times 10^{-20} g$$
Formula unit mass of $$NaHCO_{3}$$ is :
  • $$84\ u$$
  • $$76\ u$$
  • $$52\ u$$
  • $$64\ u$$
Which among the following has molecular mass of 36.5 u?
  • Carbon molecules
  • Hydrogen molecules
  • Sulphur molecules
  • Hydrochloric acid
Molecular mass of nitric acid is:
  • $$22\ u$$
  • $$12\ u$$
  • $$33\ u$$
  • $$63\ u$$
Hydrogen combines with oxygen in a 1:8 weight ratio to form water. If every molecule of water contains two atoms of hydrogen and one atom of oxygen, an atom of oxygen must weigh:
  • 8 times the mass of a hydrogen atom
  • 16 times the mass of a hydrogen atom
  • 1/16 times the mass of a hydrogen atom
  • 1/8 times the mass of a hydrogen atom
1.008 grams of hydrogen combines with 35.453 g of chlorine to form 36.463 g of a pure compound (hydrogen chloride). Dalton's explanation for this experimental fact might be: 
  • One atom of hydrogen combines with 35.453 atoms of chlorine in this reaction
  • Hydrogen and chlorine atoms always combine in a 1:35 ratio.
  • Chlorine accepts hydrogen's electron to form polar covalent hydrogen chloride
  • Hydrogen and chlorine atoms aren't created or destroyed in the process so the reactant mass is the same as the product mass.
The symbol of copper is:
  • $$Co$$
  • $$Cr$$
  • $$Cp$$
  • $$Cu$$
What is the atomic mass (u) of chlorine?
  • 34
  • 35.5
  • 33
  • 35
The illustrations show a conservation-of-mass experiment. The solution in the beaker lost mass because
439573.jpg
  • materials have less mass at high temperatures
  • the mass of the reactants and products was less than $$100\ g$$
  • sodium sulfate $$(Na_{2}SO_{4})$$ is lighter than air
  • some of the water molecules turned into gas
In the procedure shown above, a calcium chloride solution is mixed with a sodium sulfate solution to create the products shown. Which of the following is illustrated by this activity?
439568.jpg
  • Law of conservation of mass
  • Law of definite proportions
  • Dalton's law atomic theory
  • Theory of covalent bonding
Mass can neither be created nor destroyed. This is in agreement with which law of chemical combination?
  • Law of definite proportion
  • Law of multiple proportion
  • Law of conservation of mass
  • Law of conservation of momentum

Compounds formed by metals and non-metals contain charged species which are known as:
  • cations
  • anions
  • Both A and C
  • None of the above
Which is not one of the laws of chemical combinations?
  • Law of multiple proportion
  • Law of conservation of mass
  • Law of conservation of energy
  • Law of definite proportion
Calculate the formula unit mass (u) of $$\displaystyle { Na }_{ 2 }O$$ .
$$Atomic \ mass \ of \ Na = 23 \ u, O=16 \ u$$
  • $$60 $$
  • $$ 62 $$
  • $$ 61 $$
  • $$ 59 $$
In a chemical reaction, $$100 g$$ baking soda mixture containing sodium bicarbonate and vinegar on heating gives $$43 g$$ of carbon dioxide gas. What mass of solid residue is left in food?
  • $$54\ g$$
  • $$55\ g$$
  • $$56\ g$$
  • $$57\ g$$
The formula unit mass of $$X$$ is $$342\ u .$$ Among the following, X is :
  • $$H_2SO_4$$
  • $$PbI_2$$
  • $$Al_{2} (SO_{4})_{3}$$
  • $$Al(OH)_3$$
Formula unit mass of $$CaCO_{3}$$ is:
  • $$104\ u$$
  • $$106\ u$$
  • $$100\ u$$
  • $$1144\ u$$
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