Spot the one that does not fit

Exercise and reference answers

Questions

1. Items

   1. Dioptre
   2. Concave
   3. Convex
   4. Plane

   Odd item

   Dioptre

2. Items

   1. Centre C
   2. Radius R
   3. Focus F
   4. Mass M

   Odd item

   Mass M

3. Items

   1. Rear-view
   2. Convex mirror
   3. Erect image
   4. Burning paper

   Odd item

   Burning paper

4. Items

   1. Object distance
   2. Image distance
   3. Focal length
   4. Refractive index

   Odd item

   Refractive index

Instructions

Tap the item that does not belong with the rest.

Explanation