Why does calcium float on water?

List two properties of gold and silver which make them most suitable for making ornaments according to our need.

An element forms an oxide A₂O₃ which is acidic in nature. Identify A as a metal or non-metal.

By which method metals of high reactivity are purified?

A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.

Name the process by which sulphide ores are concentrated.

What is the anode mud?

Give reason for the following:

(a) Sodium metal is kept immersed in kerosene.

(b) Blue colour of copper sulphate solution disappear when some aluminium powder is added in it.

The electronic configurations of three elements X, Y and Z are X -2, 8; Y – 2, 8, 7 and Z – 2, 8, 2. Which of them is a metal and a non-metal?

What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?

The reaction of a metal ‘X’ with Fe₂O₃ is highly exothermic and is used to join broken railway, tracks. Identify metal ‘X’. Write the balanced chemical equation of its reaction with Fe₂O₃. State the special name given to this reaction.

What will you observe when:

(a) Some zinc pieces are put into copper sulphate solution?

(b) Some silver pieces are put into green coloured ferrous sulphate solution?

Give the formulae of the stable binary compounds that would be formed by the combination of following pairs of elements

(a) Mg and N₂

(b) Li and O₂

(c) Al and Cl₂

(d) K and O₂

Write the chemical equations for the reactions taking place when:

(a) Magnesium ribbon is burnt in presence of air.

(b) Sodium metal catches fire in contact with water.

(c) Steam is passed over hot aluminium.

Compare the properties of a typical metal and a non-metal on the basis of the following:

i. Nature of the oxide formed by them

ii. Conductivity

Name a non-metal which is lustrous and a metal which is liquid at the room temperature.

A compound ‘X’ conducts electricity and is soluble in water. What kind of compound is X, ionic or covalent? Assign other two properties of compound X other than given in the question.

An alkali metal A gives a compound B (molecular mass=40) on reacting with water. The B gives a soluble compound C on treatment with aluminium oxide. Identify A,B, and C and give the reaction involved.

With the help of a labelled diagram, explain the process of electrolytic refining of copper.

Name the substance formed on the surface of copper when it reacts slowly with moist CO₂ in the air.

The electronic configuration of a magnesium atom is 2, 8, 2 and that of a chlorine atom is 2, 8, 7. State the type of bond formed between the two and the formula of the compound formed. Show its formation with the help of electron-dot structure. Also list its two properties.

Metals react with water to form their oxides or hydroxides. State the special name given to the metallic oxides which dissolve in water.

Explain the reactions of different metals with hot water, cold water and steam. Give one example with a proper balanced chemical equation. Name two metals which do not react with any form of water.

Given below are the steps for extraction of copper from its ore. Write the reaction involved.

a. Roasting of copper (I) Sulphide

b. Reducing of copper (I) oxide with copper (I) sulphide

c. Electrolytic refining

Draw a neat and well-labelled diagram for electrolytic refining of copper.

Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.