18. The most densest substance on the Earth is
19. A camera uses a __________ to form an image.
(A) convex lens
(B) concave lens
(C) condenser lens
(D) none of these
20. Which from the following is NOT a conductor?
(D) All are conductors
21. Hazrat Ali (R.A) was martyred in the __________ Hijrah.
22. Which country is called the “Land of Prophets”?
(A) Saudi Arabia