HARD
9th Foundation
IMPORTANT
Earn 100

Observe the given flow chart and answer the following questions.

 

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What are c and d?

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Important Questions on Atoms and Molecules

MEDIUM
9th Foundation
IMPORTANT
NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 3

180 g of water can be represented as

(i) 5 g mole of water
(ii) 10 moles of water
(iii) 6.023×1023 molecules of water
(iv) 6.023×1024 molecules of water.

HARD
9th Foundation
IMPORTANT
NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 4
Which of the following statements is/are correct?
(I) 5 moles of CO2 and 5 moles of H2O have the same mass.
(II) 100 g of NH3 has more atoms than that present in 100 g of N2.
(III) 16 g of solid sulphur contains 3.76×1022 molecules.
HARD
9th Foundation
IMPORTANT
NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 5
Two flasks I and II contain oxygen O2 and ozone O3 respectively. Flask I contains 0.5 mole of oxygen while flask II contains 0.4 mole of ozone. Which of the two flasks have a greater number of oxygen atoms?
MEDIUM
9th Foundation
IMPORTANT
NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 6
An element X forms an oxide with formula X2O3. The formula of its sulphate and phosphate will be respectively.
MEDIUM
9th Foundation
IMPORTANT
NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 7
Which of the following statements are incorrect?
I Phosphate ion is a trivalent and positive ion.
II Calcium ion is trivalent and positive.
III Phosphorus is a polyatomic molecule.
IV Aluminium ion is divalent and positive.
MEDIUM
9th Foundation
IMPORTANT
NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 8

Fill in the blanks by selecting the option with the correct sequence of words. The symbolic representation of a molecule showing actual number of various atoms present in it is called its X formula. The number of atoms of all elements present in a molecule is known as its Y. Z formula gives the simplest ratio of atoms present in one molecule of the compound.

  X Y Z
(A) Chemical Valency Molecular
(B) Molecular Valency Chemical
(C) Empirical Atomicity Molecular
(D) Molecular Atomicity Empirical

 

HARD
9th Foundation
IMPORTANT
NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 9
A sample of ammonia weighs 4 g. What mass of sulphur dioxide contains the same number of molecules as are in 4 g of ammonia?
HARD
9th Foundation
IMPORTANT
NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 10
An ionic compound of element M and chlorine has the formula, MCl3. The molecular mass of MCl3 is 118.5. What will be the molecular mass of the oxide of element M ?