Metals and Non-Metals — Science STD 10 — Question

An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.

Give any two differences between soaps and detergents.

Write one reaction in which aluminium oxide behaves as a basic oxide and another in which it behaves as an acidic oxide.

What happens when an acid reacts with a metal carbonate? Explain with the help of an example.
Write chemical equation of the reaction involved.

What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?

A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Some metals melt on keeping them on palm. Why? Also give an example.

Metals X and Y can be recovered from the anode mud left behind after the electrolytic refining of copper metal. The coins made of metal X look new even after several years of use but the coins made of metal Y lose their shine gradually and get blackened soon. When metal X is alloyed with a small amount of metal Y, it becomes hard and hence suitable for making ornaments. What are metals X and Y ? Also state the colour of metal X.

Give reasons for the following. 
Unsaturated hydrocarbons show addition reaction. 

Why is soap not suitable for washing clothes when the water is hard?