an object 5cm in size is placed at 25cm in front of a concave mirror of a focal length 15cm. at what distance from a mirror should a screen be placed inorder to obtain a sharp image?find the nature of size of the image?​

The passing of heat through a material while the material itself stays in place. a. radiation b. conduction c. convection

Which is the correct symbol for an isotope of iodine with 53 protons and 78 neutrons?

Nacidified solution was electrolyzed using copper electrodes. a constant current of 1.18 a caused the anode to lose 0.584 g after 1.52 ✕ 103 s. given that the charge of an electron is 1.6022 ✕ 10−19 c, calculate avogadro's number. assume that copper is oxidized to cu2+ ions.