Answer the following and add solutions to the required items

19. This class is intended primarily for waters having watersheds which are uninhabited and otherwise protected and which require only approved disinfection in order to meet the National Standards for Drinking Water (NSDW) of the Philippines a. Class A b. Class AA 20. Any matter found in the atmosphere other than oxygen, nitrogen, water vapor, carbon health or the environment. Class B d. Class C dioxide, and the inert gases in their natural or normal concentrations, that is detrimental to a. Air contaminant b. air quality c. air pollutant 21.A 250 N box hangs from a rope. If the box is pushed with a horizontal force of 145 N. the angle between the rope and the vertical is approximately, d. none of the above (A) 30 (B) 60 (C) 450 (D) 750 the ball is; 22.A 0.5 kg ball travels in a circle 40 cm radius at a speed of 4 m/s. The centripetal force acts on (A) 0.05 N (C) 0.2 N (B) 5 N (D) 20 N 23.A 50 kg runner covered a distance of 100 m in 5 s. What is the momentum of the runner? (A) 2.5 kg m/s (C) 10 kg m/s (B) 1,000 kg m/s (D) 25,000 kg m/s 24.A 60-kg skater pushes a 50-kg skater, who moves away at 2 m/s. as a result, the first skater moves backward at; (A) 0.6 m/s (C) 1.7 m/s (B) 2.0 m/s (D) 2.4 m/s 25.A 10 N box is lying along the floor. The coefficient of static and kinetic friction between the surface is 0.4 and 0.3 respectively. What force is needed to keep the block moving at constant speed when set up in motion? (A) 0 (C) 3N (B) 4 N (D) 10 N 26. Two charges of 1 JC each are separated 10 cm apart. The potential energy between them would be; (C) 0.9 J (A) 0.09 J (D) 900,000 J (B) 90,000 J 0.06 cm. In order to produce an electric 27. The gap between electrodes in a spark plug is spark in a gasoline-air mixture, the electric field must reach a value of 3.0 x10 N/C. What minimum voltage must be supplied by the ignition circuit when starting the car? (C) 5 KV (A) 500 V (D) 180 KV (B) 1.8 kV