(3)

Convex mirrors are used for rear view on vehicles. We use only convex mirrors for rear view. Convex mirrors will always give erect and diminished image of the object. They provide a wider field for clear view. For this reason, the convex mirrors are fitted on both sides of the vehicles. Thus, the assertion is true but reason is false.

(1)

When the light travels from one medium to another, its speed changes so, it bends from its path. Thus, both assertion and reason are correct and reason is the correct explanation of the assertion.

(4)

We know that the path of light passing through a colloidal solution becomes visible because light is scattered by relatively larger particles. But the path of light passing through a clear solution is not visible because of small particle size do not come its way. Thus, assertion is false but reason is true.

(4)

When a ray of light travels from air to water, its speed slows down because we know that the velocity is slower in a denser medium (water) to rarer medium (air). Thus, assertion is false but reason is true.

(1)

A ray of light that travels obliquely from one transparent medium to another will change its direction in the second medium. It is nothing but the process called refraction. This occurs due to change in the speed of light as it enters from one transparent medium to another. Thus, both assertion and reason are correct and reason is the correct explanation of the assertion.

(2)

We know that the refractive index of kerosene is 1.44 and the refractive index of water is 1.33. It shows that kerosene is optically denser than water. But the mass density of kerosene is lesser than water. So, there is no relation between mass density and optical density. Therefore, it clearly defines that an optically denser medium may not possess greater mass density. Thus, the given assertion and reason are correct but reason is not the correct explanation of assertion.

(3)

Owls can move freely during night, because they have large number of cones on their retina which help them to see in night. Thus, assertion is true but reason is false.

(3)

Shining of air bubble in water is on account of total internal reflection. Thus, assertion is true but reason is false.

(1)

Concave mirrors converge the light rays falling on it to a point. So large concave mirrors are used to concentrate sunlight to produce heat in solar cookers. Thus, both assertion and reason are correct and reason is the correct explanation of the assertion.