Find examples where the four daughter cells from meiosis are equal in size and where they are found unequal in size.

Name any four sites where ribosomes are present in plant cells.

An object 5cm in length is held 25cm away from a converging lens of focal length 10cm. Draw the ray diagram and find the position, size and the nature of the image formed.

A charge Q is distributed over two concentric hollow spheres of radii r and R where R>r. such that the surface densities are equal. Find the potential at the common centre.

A stone is dropped from the top of a tower 100m high. At the same time another stone is thrown vertically upwards from the ground with a velocity of 50 ms^-1 . Find when and where the stones will meet.

An object of size 7.0cm is placed at 27cm in front of a concave mirror of focal length 18cm. At what distance from the mirror should a screen be placed,so that a sharp focussed image can be obtained? Find the size and the nature of the image.

From the top of a tower 100m in height, a ball is dropped and at the same time another ball is projected vertically upwards from the ground with a velocity of 25ms^-1 . Find when and where two balls will meet.

Take a sheet of paper. Measure its area. Pile up such sheets of paper of same size to make cuboid. Measure the height of this pile. Find the volumne of the couboid by finding the product of the area of the sheet and the height of this pile of sheets. This activity illustrates the idea that volume of a solid can ve deduce by thsi method also (if the base and top of the solid are congruent and parallel to each other and its edges are perpendicular to the base). Can you think of such objects whose volumne can be found by using this method?