Answer: Option A. -> True
:
A
A concave lens always forms a virtual image no matter where the object is. A concave lens is a diverging lens.It causes light to spread out, resulting in a smaller image for the viewer.

Answer: Option B. -> False
:
B
Convex mirror always forms a virtual image.A concave mirror can form a real or a virtual image depending on the distance of the object and the mirror.

Answer: Option D. -> dispersion
:
D
When light rays are passed through a prism, the phenomenon that happens is knownas the dispersion of light.The splittingof whitelightinto its constituentcolors is known asdispersion.

Answer: Option C. -> Indigo
:
C
The letter "I” in "VIBGYOR” represents the colour "indigo”. VIBGYOR stand for violet, indigo, blue, green, yellow, orange and red.

Answer: Option D. -> (A)-2, (B)-1, (C)-4, (D)-3
:
D
A plane mirror forms a virtual and erect image. The size of an image is the same as the size of the object.
A convex mirror always forms a virtual, erect anddiminished image.
A convex lens can form enlarged images and thus are used in magnifying glass and microscope.
Dentistsuse a concave mirrortosee an enlarged imageof theteeth. If an object is placed close to aconcave mirrorit a forms an erect andenlarged imageof the object.

Answer: Option D. -> NON
:
D
Image formed by a plane mirror is laterally inverted and therefore the letters get inverted about the vertical axis.A word that is horizontally symmetrical about its centre letter would read the same in a mirror.

Answer: Option A. -> True
:
A
Yes, a convex lens is the one which is thicker in the middle and thinner at the edges.
Convex lenses are thicker at the middle and therefore therays of light that pass through the lens are brought closer together (they converge). Hence aconvex lens is aconverging lens.

Answer: Option A. -> True
:
A
Real images are formed on screen due to the actual intersection/meeting of rays. Virtual images, on the other hand, are result of rays appearing to meet at a point. So, we can obtain a real image on a screen. E.g. The image of the sun obtained on a piece of paper using a concave mirror.

Answer: Option C. -> 15 cm
:
C
For a convex mirror, the radius of curvature $R$, is twice itsfocal length $f$.
$R=2f$
$30=2f$
$f=15$
Therefore, the focal length$f=15cm$

Answer: Option B. -> False
:
B
The image formed by the convex lens can be real or virtual depending on the distance between the object and the lens.Real images only occurfor objects which are placed outside and far from the convex lens.Virtual images are formed by placing an object between focus and pole of the mirror.