Metals and Non-Metals — Science STD 10 — Question

Metal A burns in air, on heating, to form an oxide A₂O₃ whereas another metal B burns in air only on strong heating to form an oxide BO. The two oxides A₂O₃ and BO can react with hydrochloric acid as well as sodium hydroxide solution to form the corresponding salts and water.

1. What is the nature of oxide A₂O₃?
2. What is the nature of oxide BO?
3. Name one metal like A.
4. Name one metal like B.

1. Electropositive nature of the element(s) increases down the group and decreases across the period.
2. Electronegativity of the element decreases down the group and increases across the period.
3. Atomic size increases down the group and decreases across a period (left to right).
4. Metallic character increases down the group and decreases across a period.

On the basis of the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9.

1. Name the most electropositive element among them.
2. Name the most electronegative element.
3. Name the element with smallest atomic size.
4. Name the element which is a metalloid.
5. Name the element which shows maximum valency.

Esters are When ester treated with an alkali, the reaction gives ethanol and sodium ethanoate. This reaction is called saponification reaction because this reaction forms the basis of preparation of soap. This can be given by following equation.

Give one example each of a chemical reaction characterised by:

1. Evolution of a gas.
2. Change in colour.
3. Formation of a precipitate.
4. Change in temperature.
5. Change in state.

Gas A, which is the major cause of global warming, combines with hydrogen oxide B in nature in the presence of an environmental factor C and a green material D to form a six carbon organic compounds E and a gas F. The gas F is necessary for breathing.

1. What is gas A?
2. What is the common name of B?
3. What do you think could be C?
4. What is material D? Where is it found?
5. Name the organic compound E.
6. What is gas F? Name the natural process during which it is released.

Write the equations for the reactions of:

1. Magnesium with dilute hydrochloric acid.
2. Aluminium with dilute hydrochloric acid.
3. Zinc with dilute hydrochloric acid.
4. Iron with dilute hydrochloric acid.

Name the products formed in each case. Also indicate the physical states of all the substances involved.

A compound C (molecular formula, C₂H₄O₂) reacts with Na-metal to form a compound R and evolves a gas which burns with a pop sound. Compound C on treatment with an alcohol A in presence of an acid forms a sweet smelling compound S (molecular formula, C₃H₆O₂). On addition of NaOH to C, it also gives R and water. S on treatment with NaOH solution gives back R and A.

Identify C, R, A, S and write down the reactions involved.

Elements forming ionic compounds attain noble gas configuration by either gaining or losing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this manner to form its compounds. Name the type of bonds formed in ionic compounds and in the compounds formed by carbon. Also give reason why carbon compounds are generally poor conductors of electricity.

With the help of a suitable example, explain how ionic compounds are formed State any three general properties of ionic compounds.

A red-brown metal X forms a salt XSO₄. When hydrogen sulphide gas is passed through an aqueous solution of XSO₄, then a black precipitate of XS is formed alongwith sulphuric acid solution.

1. What could the salt XSO₄ be?
2. What is the colour of salt XSO₄?
3. Name the black precipitate XS.
4. By using the formula of the salt obtained in (a) above, write an equation of the reaction which takes place when hydrogen sulphide gas is passed through its aqueous solution.
5. What type of chemical reaction takes place in this case?