Write the name and formula of the first member of the carbon compounds having functional group-CHO.

(a) How are the following related?

(i) Number of valence electrons of different elements in the same group.

(ii) Number of shells of elements in the same period.

(b) How do the following change?

(i) Number of shells of elements as we go down a group.

(ii) Number of valence electrons of elements on moving from left to right in a period.

(iii)Atomic radius in moving from left to right along a period.

(iv) Atomic size down a group.

A 2.4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 18 cm. The distance of the object from the lens is 12 cm. Find the position, size and nature of the image formed, using the lens formula.

State one role of ciliary muscles in the human eye.

Write the name and formula of a molecule made up of three atoms of oxygen.