Acids, Bases and Salts — Science STD 10 — Question

A four carbons atoms containing neutral organic compound X reacts with sodium metal to evolve a gas which burns with 'pop' sound. Another four carbon atoms containing carbon compound reacts with sodium hydrogen carbonate to evolve a gas which turns lime water milky. When compounds X and Y are heated together in the presence of a little of concentrated sulphuric acid, then a new compound Z is formed.

1. What is compound X? Also write its formula.
2. What is compound Y? Also write its formula.
3. What is compound Z? Also write its formula.
4. What type of smell is given by compound Z?
5. What is the general name of compounds like Z?
6. What is the general name of the reaction which which takes place between X and Y to form Z?

During the reaction of some metals with dilute hydrochloric acid, following observations were made.

1. Silver metal does not show any change.
2. The temperature of the reaction mixture rises when aluminium (Al) is added.
3. The reaction of sodium metal is found to be highly explosive.
4. Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.

Explain these observations giving suitable reasons.

When an object made of metal A is kept in air for a considerable time, it loses its shine and becomes almost black due to the formation of a layer of substance B. When an object made of another metal C is kept in damp air for a considerable time, it gets covered with a green layer of substance D. Metal A is the best conductor of electricity whereas metal C is the next best conductor of electricity.

1. What is metal A?
2. What is metal C?
3. Name the substance B.
4. Name the substance D.
5. What type of chemical can be used to remove the green layer from metal C and clean it? Why?

Explain the cleansing action of soap. Draw diagrams to illustrate your answer.

What is a functional group? Give examples of four different functional groups.

Two metals X and Y form the salts XSO₄ and Y₂SO₄, respectively. The solution of salt XSO₄ is blue in colour whereas that of Y₂SO₄ is colourless. When barium chloride solution is added to XSO₄ solution, then a white precipitate Z is formed alongwith a salt which turns the solution green. And when barium chloride solution is added to Y₂SO₄solution, then the same white precipitate  Z is formed alongwith colourless common salt solution.

1. What could the metals X and Y be?
2. Write the name and formula of salt XSO₄.
3. Write the name and formula of salt Y₂SO₄.
4. What is the name and formula of white precipitate Z?
5. Write the name and formula of the salt which turns the solution green in the first case.

What is a functional group? Give examples of four different functional groups.

1. List in tabular from three chemical properties on the basis of which we can differentiate between a metal and a non-metal.
2. Give reasons for the following:

1. Most metals conduct electricity well.
2. The reaction of iron (III) oxide [Fe₂O₃] with heated aluminium is used to join cracked machine parts.

A black metal oxide XO is used as a catalyst in the preparation of oxygen gas from potassium chlorate. The oxide XO is also used in ordinary dry cells. The metal oxide XO cannot be reduced satisfactorily with carbon to form metal X.

1. Name the metal X.
2. Name the metal oxide XO.
3. Which reducing agent can be used to reduce XO to obtain metal X?
4. Name another metal which can also be extracted by the reduction of its oxide with the above reducing agent.

A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identity X, Y, G and Z.