Carbon and its Compounds — Science STD 10 — Question

You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

A cleaned aluminium foil was placed in an aqueous solution of zinc sulphate. When the aluminium foil was taken out of the zinc sulphate solution after 15 minutes, its surface was found to be coated with a silvery grey deposit. From the given observation, what can be concluded?

Fill in the missing data in the following table.

	Name of the salt	Formula	Salt obtained from
			Base	Acid
1.	Ammonium chloride	NH4Cl	NH4OH	-
2.	Copper sulphate	-	-	H2SO4
3.	Sodium chloride	NaCl	NaOH	-
4.	Magnesium nitrate	Mg(NO3)2	-	HNO3
5.	Potassium sulphate	K2SO4	-	-
6.	Calcium nitrate	Ca(NO3)2	Ca(OH)2	-

What is a soap? Name one soap.

Why do elements in the same group show similar properties but the elements in different groups show different properties?

What is the difference between a cation and an anion? How are they formed? Give the names and symbols of one cation and one anion.

When a piece of limestone reacts with dilute HCl, a gas X is produced. When gas X is passed through lime water then a white precipitate Y is formed. On passing excess of gas X, the white precipitate dissolves forming a soluble compound Z.

1. What are X, Y and Z?
2. Write equations for the reactions which take place:

1. When limestone reacts with dilute HCl.
2. When gas X reacts with lime water to form white precipitate Y.
3. When excess of gas X dissolves white precipitate Y to form a soluble compound Z.

What is meant by ‘rusting’? With labelled diagrams describe an activity to find out the conditions under which iron rusts.

Write the structural formula of ethanol. What happens when it is heated with excess of conc. H₂SO₄ at 443 K? Write the chemical equation for the reaction stating the role of conc. H₂SO₄ in this reaction.