EASY
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The product formed after burning of aluminium in air is-

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Important Questions on Periodic Classification of Elements

EASY
The name of metal which decomposes water in cold is
MEDIUM

Statement (A): Iron does not burn on heating.

Statement (B): Iron filings burn vigorously when sprinkled in the flame of the burner.

MEDIUM
To design the body of an aircraft aluminium alloys are used. Give reasons.
EASY

Attempt the following:

The metal sodium is kept immersed in Kerosene oil in the school laboratory. Why it is not kept the open?

MEDIUM

An element X (atomic number 20) reacts with another element Y (atomic number 17) to form a compound X. Which of the following statement are true regarding compound Z. Which of the following statement are true regarding this compound?

I. Molecular formula of of X is XY2.

II. X and Y are joined by sharing of electrons.

III. Z imparts characteristic flame colour.

IV. It is soluble in water.

MEDIUM

The equation of the reaction when aluminium is heated in air is given below.

x Al + yO2  zAl2O3

The value of ‘z’ when the reaction is balanced is:

EASY

Give balanced chemical equation for following reaction-

Na + O2          Na2O

EASY
The name of the metal that is immersed in kerosene oil is
MEDIUM
What happens when metals are burnt in the air? Give one example.
MEDIUM

Why is sodium kept immersed in kerosene oil? 

EASY

Give reason:

Metals like sodium and potassium are stored under oil.

MEDIUM
What happens when sodium and potassium reacts with oxygen? Explain with reaction.
EASY
State reasons for the following: Sodium and potassium metals are kept immersed under kerosene oil.
EASY
Write chemical equations for reactions taking place when sulphur dioxide gas is dissolved in an excess of NaOH solution.
MEDIUM

Write the chemical equation for the following events.

Aluminium came in contact with air.

HARD
What happens when sodium and potassium reacts with oxygen? Explain with reaction.
MEDIUM

You could have noted that when copper powder is heated in a china dish the surface of copper becomes black coloured.

What is the black substance?