Answer:1:En química, el número másico o número de masa es la suma del número de protones y el número de neutrones del núcleo de un átomo. Se simboliza con la letra A (el uso de esta letra proviene de alemán Atomgewicht, que quiere decir peso atómico, aunque sean conceptos distintos que no deben confundirse).
2:
Answer:
The law of reflection states that the angle of incidence and the angle of reflection are always equal.
Answer: 25%
Explanation: According to the Florida Industrial and Phosphate Research Institute, Florida’s phosphate mining accounts for about 75% of the phosphate used in the United States, as well as about 25% phosphate used around the world. Although first mined in England in 1847, and used as fertilizer, In 1881, a civilian employee, J Francis Le Baron discovered Phosphate pebbles in peace river, and then, a hard rock phosphate district was discovered in north central Florida after that which began the Phosphate mining industry in Florida. Phosphorus rock supplies the phosphorus element in the fertilizer mix of nitrogen-phosphorus-potassium that is used as fertilizer to aid in growth of plants.
