Electricity — Science STD 10 — Question

Name one variation in humans connected with ears.

Name two metals which can, however, liberate hydrogen gas from very dilute nitric acid.

Write chemical formula for rust.

Why is it wrong to treat a wasp sting with baking soda solution?

The pH of soil A is 7.5 while that of soil B is 4.5. Which of the two soils, A or B, should be treated with powdered chalk to adjust its pH and why?

Name two waste materials which can be recycled.

Why does-the colour of copper sulphate solution change when an iron nail is kept immersed in it?

If two lenses with focal lengths 10 cm and – 20 cm respectively are kept in contact with each other, what will be the effective power of the combination of the lenses?

State whether the following statement is true or false: The sex of an infant is not a case of inheritance of characteristics.

Skin : Keratin :: Blood : …………