periodic classification of elements — Science STD 10 — Question

Translate the statements into chemical equations and then balance them:
Potassiam metal reacts with water to give potassium hydroxide and hydrogen gas.

Name the instrument used to measure electric potential difference.

How much is the equivalent resistance of a series connection?

Name the solution which is used for dissolving gold.

What are the characteristics of respiratory surface?

Choose one correct options from those given below each question:
Which of the following are not correct for carbon compounds ?

Name the three main common refractive defects of vision.

What type of oxides are formed when non-metals combine with oxygen?

A person got his eyes tested by an optician. The prescription for the spectacle lenses to be made reads:
Right eye: +2.00 D, Left eye: +2.50 D
(a) State whether these lenses are thicker in the middle or at the edges.
(b) State whether these spectacle lenses will converge light rays or diverge light rays.