The atomic number of an element is 16.Predict

i) the number of valence electrons in its atom

ii)its valency

iii) its group number

iv) whether it is a metal or a non-metal

v) the nature of oxide formed by it

vi)the formula of its chloride

State any four characteristics of the image of an object formed by a plane mirror.

Draw a ray diagram to show the refraction of light through a glass prism. Mark on it
a) the incident ray, b) the emergent ray and c) the angle of deviation.

24.

Explain with the help of a diagram, how we are able to observe the sunrise about two minutes before the sun gets above the horizon?

An object is placed between infinity and the pole of a convex mirror. Draw a ray diagram and also state the position, the relative size and the nature of the image formed.

What is the principle of reversibility of light? Show that the incident ray of light is parallel to the emergent ray of light when light falls obliquely on a side of a rectangular glass slab.

What eye-defect is myopia? Describe with a neat diagram how this defect of vision can be corrected by using a suitable lens?

What is meant by biological magnification?

Give an example to illustrate that indiscriminate use of pesticides may result in the degradation of the environment.

List any, four reasons for vegetative propagation being practised in the growth of some type of plants.