31.

Which of the following fact is incorrect about monocotyledonous plants?

A.

Seeds has single cotyledon

B.

Leaves have parallel venation

C.

Fibrous root system present

D.

Flowers are pentamerous

32.

Which of the following fact is incorrect about mitosis?

A.

It occurs only in body cells

B.

Mitosis has two divisions

C.

Maintenance of 2n chromosomes

D.

Two diploid cells are produced

33.

Which of the following is wrong?

I. Na_{2}CO_{3} is used in softening hard water

II. NaHCO_{3} is used for bleaching cotton and linen in textile industry

III. CaSO_{4} 1/2 H_{2}O is used for plastering fractured bones

IV. CaOCl_{2} is used in making of baking powder

34.

Focal length of a convex mirror whose radius of curvature 40 cm is

35.

A man has to exert a forceof 10N at the edge of a door to push it open. How much force will the man have to exert if he pushes the centre of the door?

36.

The first battery was made by

37.

The average height of 12 students in a class was calculated as 152 cm. On verification it was found that one reading was wrongly recorded as 148 cm instead of 172 cm. Find the correct mean height.

38.

The difference of the squares of two positive numbers is 45. The square of the smaller number is four times the larger number. Find the numbers

39.

The radius of a cart wheel is 35 cm. How many revolution does it make in travelling a distance of 154 m

40.

Saran is 6 times as old as his son Sankar. After 4 years, he will be 4 times as old as his son. What are their present ages?