Metals and Non-Metals — Science STD 10 — Question

State any three limitations of Mendeleev’s classification of elements.

The atomic number of an element is 12.

1. Write its electronic configuration and determine its valency.
2. Is it more reactive or less reactive than Ca (atomic number 20)? Justify your answer giving reason.
3. Is it a metal or a non-metal?
4. Write the formula of its oxide.

State in brief the method of preparation of bleaching powder. Write a balanced chemical equation for the reaction involved and state the uses of bleaching powder.

List three advantages each of:

1. Exploiting resources with short term aims.
2. Using a long term perpective in managing our natural resources.

An element X from group 2 of the periodic table reacts with an element Y from group 17 to form a compound.

1. What is the nature of the compound formed?
2. State whether the compound formed will conduct electricity or not.
3. Give the formula of the compound formed.
4. What is the valency of element X?
5. How many electrons are there in the outermost shell of an atom of element Y?

On dropping a small piece of sodium in a test tube containing carbon compound ‘X’ with molecular formula C₂H₆O, a brisk effervescence is observed and a gas ‘Y’ is produced.  On bringing a burning splinter at the mouth of the test tube the gas evolved burns with a pop sound. Identify ‘X’ and ‘Y’. Also write the chemical equation for the reaction. Write the name and structure of the product formed, when you heat ‘X’ with excess conc. sulphuric acid.

Give one example each of a salt which gives an aqueous solution having:

1. pH less than 7
2. pH equal to 7
3. pH more than 7

How is copper extracted from its sulphide ore (copper glance), Cu₂S? Explain with equations of the reactions involved.

With the help of an example, explain the process of hydrogenation. Mention the essential conditions for the reaction and state the change in physical property with the formation of the product.