The light from the torch C will not form a shadow on the screen because light travels in a straight path and will form the shadow on the same path from which it is coming.

As we know that the silvered glass surface is very smooth and shiny as well. So, this type of surface helps informing the clear image. So, silvering makes it shiny and this shiny surface in turn helps in reducing the absorption.

Colours of the shirts will remain same. We see them on the screen because pinhole camera forms the images of the object having same colour but upside down. So, yellow shirt will form yellow image and red shirt will form red image.

Transparent sheet can be made translucent by two ways
(i) By rubbing it on the ground and make it rough.
(ii) By polishing it, not completely but partially.

Yes, there are many things that could give a circular shadow if held in one way and a rectangular shadow, if held in another way, e.g. a cylindrical object, a pencil, a candle, etc.
(i) Getting a circular shadow of a candle (which is cylindrical in shape), when it is laid down horizontally

(ii) Getting a rectangular shadow of a candle while in standing or in vertical position.

No, the shadows are same for different colour of object, it is always black. Some portion of the shadow may be grey.

A chair, a painting and a shoe are opaque objects because we cannot see through them.

No, we cannot observe any shadow without any source of light.

Shadow of flying aeroplane cannot be seen on the earth because umbra region cannot able to reach the earth.

The object which partially allows the light to pass through it is a translucent Object, e.g. wax paper.

The shadow of the object cannot be caught if the screen and the object are very far from each other. This is the same case, the shadow of the football cannot be seen on the ground when it is kicked high in the air. This happens because if we take the object away and away from the screen, the image becomes smaller and smaller and a time comes when it disappears from the screen.

Yes, the shadow will be formed in all the cases but in all the cases, the darkness of the shadow will be different.
(i) Most of the light in case of transparent sheet will pass through the glass. So, the darkness of shadow will be very low.
(ii) Also most the light in case of muslin cloth will be reflected. So, the shadow will be darker than the transparent sheet.
(iii) While in case of plywood, all the light would be stopped completely by the plywood. So, the darkness strength will be highest in this case.