Question

CLASS-X

Subject- Chemistry

Assignment 1

Chemical Reactions and Equations

1. On heating blue coloured powder of Copper (II) Nitrate in boiling tube, copper oxide (black), oxygen gas and a brown gas X is formed

1. Write a balanced chemical equation of a reaction

2. Identify the brown gas X evolved

3. Identify the type of reaction

2. Shiny brown coloured element X on heating in air become black in colour. Name the element X and black coloured compound formed.



3. Define rancidity. Name two ways of its prevention



4. a) Why do we store silver chloride in dark bottles?

b) Silver articles turn black when kept in open for few days. Why? Name the black substance formed and give its formula (support your answer with chemical equation)



5. Name the substance oxidized and reduced in the following equation

1. CuO + H2 ->Cu + H2O



2. H2 S + Cl2 -> 2HCl + S





6 What is a chemical equation? What is the need to balance a chemical equation?

7 What happens when

• When lead nitrate solution is added to potassium iodide solution.

• Marble chips react with dilute HCl.

• Crystals of ferrous sulphate are heated strongly.

• Quicklime reacts with water.

• Magnesium ribbon is burnt in oxygen.

Support your answer with a balanced chemical equation. Also, mention the type of chemical equation.

8 Translate the following into the chemical equation and classify them:

• Lead nitrate reacts with sulphuric acid to form a ppt. of lead sulphate and nitric acid.

• Iron (III) oxide on heating with carbon monoxide gas reacts to form solid iron and liberates carbon dioxide.

• Ferrous sulphate decomposes to give ferrous oxide, sulphur dioxide and sulphur oxide.

9 Complete and balance the following equation:

• Al + Fe2O3→

• Na2SO4 + BaCl2→

• Mg + H2O →

• CuO + H2→

10. Draw a well labelled diagram showing electrolysis of water and answer the following

question:

• Which tube contains hydrogen gas?

• If the volume of hydrogen gas collected is 10ml, what will be the volume of oxygen collected

• Why do we add a few drops of dil. Sulphuric acid









Assignment -2

Chapter – Periodic Classification of Elements



1. “Hydrogen occupies a unique position in Modern Periodic Table.” Justify the statement.

2. Can the following groups of elements be classified as Dobereiner’s traids?

a)Na, S, Cl b)Be, Mg, Ca

At. Mass of Be=9; Na=23; Mg=24; Si=28; Cl=35; Ca=40

Explain by giving reasons.

3. Compare the radii of two species X and Y.

a) X has 12 protons and 12 electrons

b) Y has 12 protons and 10 electrons

Identify the species. Give reasons for your answer.

4. An element ‘X’ has number of electrons in first and fourth shell as well as in second and the third shell

a. Write the electronic configuration of the element

b. Predict the position of the element in modern periodic table.

c. What is the valency of the element?

d. Will it form ionic or covalent compound with the element Y (2,8,6)?

e. What is the nature of its oxide?

5. What were the two major shortcomings of Mendeleev’s Periodic Table? How have these been removed in the Modern Periodic Table​

Answer 1

Answer:

6. The chemical reaction is obtained when the chemicals react with heat.

When we burnt the magnesium in oxygen, then the magnesium oxide is produced.