Carbon and its Compounds — Science STD 10 — Question

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.

Name two ores of zinc. Write the names of the chemical compounds present in them and give their chemical formulae.

What current will be taken by a 920W appliance if the supply voltage is 230V?

How would these advantages differ from the advantages of using a longterm perspective in managing our resources?

What is meant by ‘refraction of light’? Draw a labelled ray diagram to show the refraction of light.

Name two devices in which electromagnets are used and two devices where permanent magnets are used.

How do stems of a plant help in excretion of gases?

A milkman adds a very small amount of baking soda to fresh milk.

1. Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
2. Why does this milk take a long time to set as curd?

Describe how an electromagnet could be used to separate copper from iron in a scrap yard.