Class 9 Practice – Level 3 – Set 2 – Atoms and Molecules.

Total questions: 15

In the reaction $ \displaystyle \text{2Al + 3C}{{\text{l}}_{2}}\to \text{2AlC}{{\text{l}}_{3}}$ , how many moles of aluminium chloride are produced from 5 moles of aluminium?

Topic: Chemical Reactions and Equations

3.5 moles

4 moles

5 moles

7.5 moles

None

How many grams of water are produced when 4 moles of hydrogen gas react with 2 moles of oxygen gas?

Topic: Chemical Reactions and Equations

18 g

36 g

54 g

72 g

None

An element has an atomic number of 26 and a mass number of 56. How many neutrons does it have?

Topic: Atomic Number and Mass Number

None

Which element has the atomic number 14?

Topic: Atomic Number and Mass Number

Magnesium

Silicon

Sulphur

Phosphorus

None

Which of the following elements is in the same group as fluorine?

Topic: Periodic Table and Elements

Oxygen

Nitrogen

Chlorine

Neon

None

What is the period number of an element with the electronic configuration 2, 8, 1?

Topic: Periodic Table and Elements

Period 1

Period 2

Period 3

Period 4

None

In the reaction $ \displaystyle \text{2Na + C}{{\text{l}}_{2}}\text{ }\to \text{ 2NaCl}$, how many grams of NaCl are produced from 23 grams of sodium?

Topic: Stoichiometry

23 g

46 g

58.5 g

117 g

None

How many moles of oxygen are required to react completely with 4 moles of sulphur in the reaction $ \displaystyle 2S\text{ }+\text{ }3{{O}_{2}}\to \text{ }2S{{O}_{3}}$ ?

Topic: Stoichiometry

2 moles

3 moles

4 moles

6 moles

None

What is the empirical formula of a compound with the molecular formula $ \displaystyle {{C}_{6}}{{H}_{{12}}}O$ ?

Topic: Empirical and Molecular Formulas

$ \displaystyle {CHO}$

$ \displaystyle {C{{H}_{2}}O}$

$\displaystyle {{{C}_{2}}{{H}_{4}}{{O}_{2}}}$

$ \displaystyle {{{C}_{3}}{{H}_{6}}{{O}_{3}}}$

None

10.

A compound has an empirical formula of $ \displaystyle C{{H}_{2}}O$ and a molar mass of 180 g/mol. What is its molecular formula?

Topic: Empirical and Molecular Formulas

$ \displaystyle C{{H}_{2}}O$

$\displaystyle {{{C}_{2}}{{H}_{4}}{{O}_{2}}}$

$ \displaystyle {{{C}_{3}}{{H}_{6}}{{O}_{3}}}$

$ \displaystyle {{{C}_{6}}{{H}_{{12}}}{{O}_{6}}}$

None

11.

In the reaction $ \displaystyle 2{{H}_{2}}+\text{ }{{O}_{2}}\to \text{ }2{{H}_{2}}O$, how many moles of water are produced from 3 moles of hydrogen?

Topic: Chemical Reactions and Equations

2 moles

3 moles

4 moles

6 moles

None

12.

How many grams of $ \displaystyle {C{{O}_{2}}}$ are produced when 5 grams of carbon is burned in excess oxygen?

Topic: Chemical Reactions and Equations

18.33 g

16.67 g

13.33 g

11.67 g

None

13.

How many molecules are there in 5 grams of hydrogen gas $ \displaystyle \left( {{{H}_{2}}} \right)$ ?

Topic: Mole Concept

$ \displaystyle {1.505\text{ }\times \text{ }{{{10}}^{{23}}}}$

$ \displaystyle {2.505\text{ }\times \text{ }{{{10}}^{{23}}}}$

$ \displaystyle {1.505\text{ }\times \text{ }{{{10}}^{{24}}}}$

$ \displaystyle {3.011\text{ }\times \text{ }{{{10}}^{{24}}}}$

None

14.

1 unit or 1 atomic mass unit means:

Mass of one proton

1/12th mass of C-12 atoms

$ \displaystyle {1.67\text{ }\times \text{ }{{{10}}^{{-27}}}}$ kg

All of the above

None

15.

A sample of ammonia molecule irrespective of source contains 82.35% Nitrogen and 17.65% of Hydrogen by mass. This data supports:

Topic: Molecular Mass and Mole Concept

Law of Multiple Proportions

Law of Conservation of Mass

Avogadro’s Law

Law of Definite Proportions

None

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Class 9 Practice – Level 3 – Set 2 – Atoms and Molecules.

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